Hey Seth, due to the logarithmic scale by which dB is measured, a reduction in 3dB is the same halving the noise output. However for the same reason and as you discovered, it is almost undetectable by the human ear. So from and Engineering perspective this is a massive success, but practically all you've done is make your bike slightly heavier. 🤭😁 take care bro!
The biggest contributor to “noice” on any bike seems to me to be the “loose” items on a bike and the resonance of a a securely welted or molded, essentially a one piece frame. Chains have notoriously been the source of noice on bikes. If frame resonance is a bugaboo, I would suggest inserting another type of foam! Regular poly foam! This stuff is not only easier and cheaper to install, just stuff it into the cavity but it is also easily revers-able! Just pull it out! Seth, I would like to see an episode where you do this! You do an episode called “STUFF YOUR BIKE!” Stuff every nook and cranny with polyfoam@ handlebars, head tube, down tube, seat tube etc.! Let’s see the results! Good job!
To be more specific, -3db will halve the sound intensity and vice versa adding 3db will double the sound intensity but how human hearing perceives sound is different. You need to add about 10db to double the perceived sound volume and about -10db to cut the perceived sound volume to half.
@@sakusaaristo191 pretty sure that's what I said. Did you read my entire comment, particularly that bit about it being almost undetectable to the human ear?
Back in the 80's expanding foam was used to add permanant bouyancy to kayaks at either end. Issue was that it tended to absorb moisture and got heavier over time. I never used it and don't think I will be filling my bikes ant time soon!
@@bobbyhempel1513 you said "now". Do you know for a fact that closed cell expanding foam wasn't a thing in the 80's? Or did you just mean that it exists nowadays without making a statement about the 80's?
You can get weather resistant foam, but yes closed cells foam tends to be more durable for weather, but at cost of weight. Still, half a can of foam is still only maybe 300g?
I use these products in my trade from time to time. Construction to be exact. I have seen these foams bow windows and doors and lift bath tubs of the floor and crack fiberglass when not used correctly. So I see why people might be worried about cracking a bike frame. If I was going to try this (which I don't think I ever would haha) I would definitely look for the minimum expansion variants designed for windows and doors. I applaud you for trying this for us, in the name of science haha.
zatz becoz you are in meriguh and yo build walls out of woot, here in germany zis foam would start to cry and would get qnokked out by aur solid konstruction! lmao to be honest, yeah there is lots of power within that foam. but i couldn't imagine the foam is as strong to damage a serious bike frame. interesting video tho! edit: talking about alu / steel frames. don't know how it would impact on carbon frames. i have none, but i guess i would not not try it out on a carbon frame. :D
Good thing about homes is that they must be heated to at least above freezing temperature at all times, for any number of reasons. This is not how bikes are used. So you have this closed cell foam, but let's say a little bit of water finds its way into the outermost cells. Then well there's no escape. Eventually it freezes, bursts the cells, and finds in deeper. 10 years down the line you have the whole foam taking on water, perhaps not entirely full of it, but holding onto a small amount. If you have a steel frame, it's probably rusted through at that point. Carbon fibre... well it has some inherent water wicking ability and also suffers from water but it just makes it structurally less sound with heating/cooling cycles, little by little. The epoxy resin in carbon fibre can conduct the tiniest amount of water, but in general it's pretty resilint to it, but once you add glass or carbon fibre it happens to outright wick water in and concentrate it on the fibres, up to about a handful percent. If you forget to preheat a circuit board and carefully drive out the moisture, when you hot air solder, it's probably going to form a steam bubble and pop, which is very bad, it destroys vias. Carbon is similar.
Foam tires have been around for years, but they are vastly inferior to good old fashioned pneumatic tires. The only advantage they have is that they can never go flat. The disadvantages are increased weight, increased rolling resistance, and a decreased ability to absorb shock.
expanding foam in tyres will eventually disintegrate, so no its not as good an idea as you would think. Gander Flight has some videos showing it being done on his channel that may be worth a look
Stop using expanding foam on your bikes period. It's dumb and you're dumb if you do it, enjoy adding 5kg to your bike when all that foam soaks up any moisture
You can still calculate the weight if you have the leftover can (and the excess foam you played round with)... Weigh a full can, weigh the used can + foam from the clear tube etc... The difference is the weight you added to the bike. (The foam does not change weight when it expands).
@@anthonymorris8891 soooo pump out 50 grams of foam onto a piece of cellophane on some good kitchen scales... and weigh the result when it's cured.. and do the math... You can STILL calculate the weight... I just didn't want to mansplain too much otherwise I tend to write 1000 word essays... (I've reached the U-toob comment limit a few times now...)
I don't think it is correct that it loses moisture. Foam doesn't dry, it cures. Meaning the moisture isn't water that evaporates, it's foam that hardens. In fact, the instructions on the can say to mist it with water to speed cure time. I think the above measurement process would get you close. Of course, we'd have to test it to really find out.
You need an 2 part structural expanding foam. This will set inside the frame and doesn't absorb water. It also makes the frame stiffer. The spray stuff needs air to set, so it will never fully set in the middle of the frame.
Motorcyclists used a form of expanding foam for a number of years to deaden the vibration in handlebars... They also filled their handle bars with sand, and a few other vibration mitigation techniques over the years (not all at the same time). Filling the frame with foam will add weight, but it will also deaden vibration, and will help to keep the internal cables from being slapped into the frame (a potential source of noise). outside of that... minimal gains. I MIGHT consider it on the handlebars for a touring gravel bike.
I've done it. For the super light frames it can make a huge difference in noise. Particularly the ones with thin and flat sections of carbon layup that tend to act as a sound board. The downside with gap filling foam (Polymethylenepolyphenylisocyanate, propoxylated glycerin polymer) is that it stays kind of rubbery and doesn't adhere to the inside walls as well as you might think. A better foam would be something that cures firm like polyurethane. Pretty sure gap fillers used to be the polyurethane variety, but they tended to expand with more force, crushing window and door frames.
I absolutely guarantee you the people doing this are probably obese and have never worked on weight savings on themselves. What a pointless type of rider.
Also you obviously never ride in any type of weather other than a dry sunny day too, or it'd take about a week for all this shite you've emptied in your frame to become soaked with moisture just like what they used to do with kayaks to keep them buoyant until it'd absorb all water. You can sound deaden with correctly placed pieces of tape, all you did was add weight to the bike because the internet told you so.
The hollow bike frame might act as a wave-guide and direct sounds and impacts from one part of the frame to another. For example, internal sheathing around the cables inside the frame, rattling against the side of a tube near the bottom bracket, might be directed up the the seat tube and closer to the decibel meter. Sound also propagates faster through solids as well so by filling the tubes with foam you dampened a lot of those higher frequencies resonating through the frame and cavity resulting in it being more "dead" (as you put it) sounding. Those dead sounds you hear are just the undamped low frequencies that have a longer wavelength and, interestingly, they remain as loud as they originally were but lack the "sharpness" that the same noise had before you neutralized those higher frequencies. It's sort of like leaving the volume on your old school boom box at 10 but pulling down the right 3 sliders on your equalizer. You get more muffled sound and the perception that you added bass even though you didn't. Just a sidenote, I assume you read enough of reddit to know to use closed cell foam but it's worth mentioning that Great Stuff expanding foam is "closed cell" which means it won't absorb water when you do that stream crossing. Heaven help anyone who finds themselves in the middle of a long ride, a frame full of open cell foam and a bunch of water obstacles. Might want to pack an extra Clif bar for that one.
I work for an insulation company and we use spray foam insulation .It weirdly adds slot of strength to a home .It may strengthen the frame as well as dampening shocks slightly but the foam you used won't really do much because how thin of consistency the foam is.
Bianchi used, or maybe still does, fill the entire lower half of their high end road frames to "stiffen" the Bottom Bracket area of the frame. I first learned of this information around the Pantani era.
Yes indeed. You remember correctly. Came here to say the same. From the Bianchi Canada archives...... Technology Solutions Structural Foam Injection is a 2-component non-toxic foam developed by Henkel Spa Surface Technologies and patented by Bianchi for specific cycling applications, i.e., as a tube strengthening material. The results obtained through the introduction of SFI have been noteworthy: a weight increase of only 20 grams yielded a 15% improvement in stress resistance, while resistance to fatigue doubled in the bottom bracket area. All this was made possible by the special properties of this foam, which is able to distribute the loads evenly, avoiding fatigue build-up in high stress areas and in welded parts whose composition has been thermally altered.
So a hack i used to do back in the day would be filling my handlebars with foam. It damped the vibrations by like 5x and made the small bump chatter wayyyy more bearable on a long DH day.
@@nukleyar Any foam can work. it just varies in ease of use and how much dampening. Pool noodle foam is easy and cheap to cut up and insert but doesn't dampen as much as filler foam like Seth used here.
I've done this as well -- even on my Fasst Flexx bars where the elastomers already help isolate vibration, I was able to notice a small difference in reducing sidewalk buzz from riding on pavement. The Fasst bars made A/B testing easy, since I could put something in one side but not the other and compare the difference in feel in realtime. What I used was 7/8" closed cell foam backer rod -- the size is almost perfect for staying in place in a handlebar and has the added benefit vs. expansion foam that you can pull it back out later if you want. To get it to go all the way in, you can use a thin rod to push it (kind of like loading a cannon).
I mean there’s definitely something to it. Spank makes a bunch of mtb parts such as wheels and handles bars which are filled with foam in order to achieve better vibration damping, by all accounts it seems to work for that purpose. So if anything a good thing to think about next time your testing is whether or not the bike soaks up vibration better during a long sort of xc ride.
I used to work at a factory where we made spray foam. Although I'm sworn to secrecy about some things🤣🤣 I can tell you this. Today's spray foam has a closer consistency to plastic than actual foam. We used to clean up spills with acetone because it breaks it down and comes right off before actual expansion. It will continue to expand even after you think it's done
Seth- Klein bikes used to ship their beautifully painted fuselages (frames) in a box filled with expansion foam, they had plastic type bags protecting the frame from the sticky stuff, very shipping company proof when sending them around the world, not as environmentally friendly as (edible) corn starch packing peanuts, which dissolve in water. Gregg
The foam is polyurethane foam and requires 2 things to cure: moisture and ventilation. The foam they use in cars and such is most likely blended to cure inside closed sections, that's why the inside was still gooey when you removed the tumah. It's likely the foam will take a while longer to full cure, removing the cover plate to let it "breathe" might be a good idea.
I recently used some of this stuff to surround a copper pipe coming out of the wall. I was shocked to see how long it took to fully, cure/expand. 24 hours later I thought that of course it would have to be done by then, another 24 hrs later it had expanded even more, I was like what WTH?! I wonder if it will ever fully expand in his bike. When he was waiting for it to expand around the tennis ball I facepalmed so hard I hurt myself.
You need a real 2 part foam that is designed for filling structural frames. You will see a large difference in not only less resonance, but I would also expect a notable increase in rigidity, and that should change how the bike handles. Get two identical frames and fill one with a quality 2 parts frame filling foam, and get it filled to the brim in all areas, then run a side by side. Filling tires would be easy too with another 2 part foam that is designed for repeated compression and high rebound.
You've really only filled the down tube. You would need to somehow fill all of the tubes to fully test any true differences. Also, the base frequency is likely the change you feel. I remember, from an automotive noise class I took, that there are certain frequencies that are "comfortable" (to simplify the long explanation) for humans. And adding deadeners to the metal changes those frequencies. I had to go and look it up, but "Natural Frequency" is the term I was looking for when I said "base frequency".
As far as breaking frames, a few things: The RED can is for window frames and has low expansion pressure (and low expansion in general) so it will not damage or warp the window. The BLACK can (big gap filler) is high expansion high pressure and absolutely will create enough pressure to break things - though probably not a carbon tube. As someone else mentioned, these single part foams use air to sure and the red can will not cure in large sections of more than an inch or so. The black can cure at up to 3" or so. Using foam is a legitimate way to strengthen and stiffen things (and deaden sound). Hockey sticks for example use foam in selective locations and densities to tune the stiffness of the stick. There was a steel bike seat post with super thin tubing that was filled with foam in the 90s (and one frame filled with pressurised nitrogen too I think). This could be something interesting to keep trying out, however you'll need to do more research in getting the correct type of foam (try "smooth on" and boat building websites for info). You need something with a 2 part chemical cure, low density, high expansion, low to medium pressure, and closed cell for no water absorption.
@@Stevesbe They have a few variations of course, I have the red cans right next to me, used them on my windows. The red is for larger gaps, blue for smaller, but they are still both low pressure low expansion. I used the black ones for big holes, and it moves plywood, drywall and door jambs if you put it in the wrong spot.
I've done a similar thing with packaging foam. Take off the fork and that will usually give you access to the down tube, then fill it with the packaging. The nice thing is that it's reversible. Works well.
You should use a 2 part structural rigid foam, you can pour that and it'll expand within the tubes - if you're going for every last gram you can thin the walls on your tubes down a little (the real reason you hear some race builders have done it, rather than the ones they put out) because the foam helps with buckling and impact strength, as well as a bit of damping. Often the same is done with cars in the a-pillars and sills.
I would be surprised if the foam ever even dries deep down in the center of the frame. I've used alot of spray foam in construction over the years and if it can't get air it never actually dries to become foam. It turns to a permanent orange gel of sorts.
@@lossantoscity3249 not air, but moisture. Concrete is also like this, since it’s a chemical reaction taking place and not simply drying, you need all the reagents present for it to complete
2 dB at that is actually a pretty decent difference. Not that it was especially scientific test. In SAE CSC we were excited to get 1dB difference in a J1161 sound test after a component change. The decibel scale is logarithmic which is another important thing to consider here
You can buy foam filled handle bars off the shelf (Spank spike 800 vibrocore). It's meant to reduce vibration they also have carbon wheel sets with a foam filled section
2 things, I have heard of doing this for cable noises, my reaction is do they not know jagwire foam sleeves for cable housing, 2nd I do recall Bianchi doing this on one of there road bike in the bb ,added strength supposedly???
This is a little off topic, but I have found the greatest noise reduction move on my was switching to Onyx Racing hubs. They are kind of expensive, but completely silent. Most people like the bzzzzz sound of high end hubs. I used to as well until I started using these. Aside from being silent, they also have instantaneous engagement which I love for technical climbs. They are heavier than most comparably priced hubs, but I think their silence and engagement makeup for the weight.
I've used it on an older frame to quiet down a piece of a rivnut that fell in the downtube. No openings at the bottom bracket or head tube. Worked fine, no issues, though the bike did have external routing.
I enjoyed the video. A little over a year ago budget restraint we bought the mongoose ledge x1 and x2. Have ridden those stock since. Light trail riding. With plans to make them more capable. I believe they ran $400 for the x1 and $500 for the x2 from Walmart full suspension.
People who race unibody cars would fill the main support channels throughout the car to make the chassis stiffer in turn handle better. Whether it works or not 🤷♂️. The product is also different than regular spray foam. It is less pliable than regular spray foam. Just put the foam tubing on the housing. Or just don't do it!
Might have made more of a difference with acoustic rated expanding foam, that stuff is surprisingly effective for sound dampening, if often seen that as the biggest criticism of carbon frames, they're that rigid it's like a tuning fork. Also, I seem to remember someone trying it in handlebars as a home made spank vibrocore alternative, and the conclusion was the density of the foam is crucial, normal expanding foam wasn't dense enough for that application.
It makes sense. Even if the frame isn’t the source of the noise to begin with, the fact that it’s hollow and has its own resonance can be amplifying components attached to it. Also, some annoying sounds might not take up much acoustic energy and reflect much on the dB meter. My question, which I suppose you answered by not talking about it, is if there was any difference in the way the frame felt to ride. Thanks for another fun video!
Interesting idea Seth. Would be have been interesting to see what effect - if any - it has on vibration. Maybe by using an accelerometer or two on the frame to record vibration profile.
I own a spray foam insulating company and for the best results you would want to use open-cell retro-fit foam. It is designed to be pumped inside of empty, uninsulated, wall cavities using small 1/2" holes. It has the most expansion of any other type of foam. Plus, the foam we use comes in 2 parts, which mix as they are sprayen out the end of the gun/applicator.
I never thought of that. I did fill my steel chrome moly frame with helium before to save weight. It worked great for climbing. Hardly any pedaling to go uphill. The problem was going downhill. 😕
I remember early 80s dirt bike riders would do the foam to dampen the vibration in their motorcycle handlebars and as a young kid we just copied what they where doing to our bmx
Seth, could you test the largest brake rotors that you can find? I've recently seen some 246 mm Brake rotors. It would surely be interesting to see, whether their performance is on par with their diameter. Great video as always. Keep up the “scientific testing”!
Well with bigger brakes in cars. The most limiting factor is tires. If you have tires with better grip you will stop faster and more consistantly. Bigger Brakes in most cases just allow you to stop harder with more frequency since there will be more thermal mass. But then you have to consider will the extra weight cancel out the stopping power it might give.
I think most brakes have the power to lock up the tires at any time, but not heating up as fast and cooling off more quickly would be the big benefits. My nothing special MTB I always worry about overheating the brakes since I'm a big guy
We played around with handlebars thinking a sudo vibracore. The problem we ran into was the canned stuff required air to dry and never really did. I'd like to see it where it's the 2 part foam that is a chemical reaction. That seemed to work a lot better but ended up just buying vibracore bars at the end. Cool vid!
2db is considerable! -3db of difference is half of the acoustic energy. Also, it is common for meters to weigh different frequencies differently, so if it sounds "deader" it may be because it has less high frequencies and thus it will read a lower sound pressure.
2db is usually the point where it'd become detectable in person with A B testing. Harder to judge based off recordings or when you can't alternate back and forth.
You need to double the power to get a 3db gain. But, you need 9db or 10db to perceive it as double the power. A 2db difference is almost undetectable, or getting to the point its detectable. Power and perceived loudness are to different things. The last goes in the psychoacoustics domain.
@@StarAD Absolutely correct. And I would add that the SLM that Seth is using has a listed tolerance of +/- 2.0 dB (definitely not a Type 1), so the 2 dBA difference observed means nothing.
The people I rode with back in the day, and myself, used to put those foam tube thingies outside our cables that run inside the frame to stop them from making noise. The thing with filling a frame with foam seems like a not too great idea but seeing as I'm not a foam expert and that there are many types, there might be one that works. Make sure that it doesn't retain water though.
As someone who did car and home audio while I was in trade school to be a mechanic: I've used this product to fill in a seat on a shitbox car I had to drive home. I think a better idea would be to get sound dampening paste or stuffing some old towels into the frame. First on the paste: this is overkill, but you can get it for home construction and car audio installs, so a little leftover could be dicked around with on a bike project. Second on towel stuffing: While custom GIK sound panels/bass traps are amazing, you can also build them yourself. One of the cheapo things I would do for people is if they had already hung wall art with a deep box frame. Just stuffing a bunch of old towels from a thrift store in the negative space drastically improves acoustics. You can do the same with a bike if you wanted too if you have a bunch of old t-shirts, etc or those rag boxes shops get. Plus you can continue to use your tube storage options etc AND you'd always have a rag in stock while on a ride. Sound dampening is literally about absorption (and Sieben levels).
I’d be most curious if it has any potential long term chemical dissimilarity with steel, AL, or carbon. Otherwise I see no benefits to it and only potential concerns. But thanks for doing the test!
its extremely dependant on the specific type of polymer and composition used, but generally cyanate esters (which i believe are most common in these types of expansion foams) are protective against corrosion in steel. Al should not be of any issue at all either, no idea about carbon laminates either but would guess theres no significant issue.
Hi Seth, I ran your data to check to see if there is a significant difference between volume(db) with vs w/o expansion foam in the frame. I ran it through a two tailed t-test in excel and the numbers showed that the difference is not-significant. The p-value was .06 meaning that we fail to reject the null hypothesis (aka addition of foam makes no significant difference on volume of bike).
You know....I never did get to get into mountain biking like I wanted to. But, I just keep coming back to all the Berm Peak channels. Its never ending and relaxing entertainment. Love the content!
I could never get into mountain biking either, but I always enjoyed road biking. But now that I'm 52 with osteoporosis from my thyroid disease and I broke my back a few summers ago, I ride an electric bike now.
One thing I’d be concerned about, when water gets inside your frame (possibly through the cable ports or other means of entry) the foam will block the water from draining properly to the drainage holes. Can’t imagine having a pool of water sitting in your frame is good
I usually look for reason to avoid expanding foam. Cleaning it up is a nightmare, especially off your hands, arm hair and almost impossible to get out of clothes.
Every time I've ever used it, I've had to remove a couple layers of skin to get it off my hands afterwards. (I know you're supposed to wear gloves, but the stuff is hard enough to work with already and gloves just increase the PITA factor.)
I filled my racecar's chassis with structural expanding foam in 4lb density. The rigidity added to the chassis was a huge difference, I did only one side first and the car was very unbalanced from left to right corners. now both sides done it is much quieter and the sound of the doors closing is damn near that of a luxury car.
I like the idea of internal routing cables but it took me a few weeks to isolate the noise on my Trek Dual Sport. I thought it came from front fork when I go though a drop but it was from the rear brake line in the down tube. I did some research here on this site and finally decided to carefully wrap the brake line and insert to the frame with bubbled envelop from Amazon. It works. Now I know what to do if I hear that clanking noise again on my other bikes. Insulation foam is not a good idea IMHO.
Filling your handlebars with puddy or gel to reduce vibrations for the hands is something people have been playing around with for a while. Especially with motorcycles.
I just used light weight heater vent filters and stuffed a bunch in my Orbea Rallon to deaden the cable rattle. Worked brilliantly and super light weight, No mess and easy to remove. My bike runs so much quieter now.
when you want to fill a cavity with expanding foam like you used, these things use water to complete the process so, what I've seen is using a steam cleaner to kind of inject steam through the foam can nozzle and that can allow the foam to actually fill the cavity uniformly and get a much more solid result since it has the moisture it needs to complete the process. I know there are other foams that would work without pumping water into your frame but those can be pretty expensive materials.
I think that this would actualy dampen som impact on frame and make it stronger because of air you have a thick foam pushing against it. Its like having a bone with marrow and without it..which one is better. I would do that even if it added some weight.
Might be an interesting strategy for helping guide internally routes cables that don’t have glass tubes after it’s been done the first time. If any of the cables on that bike are internal (dropper), be a gent and find out for us!
Some of the high-end bicycles did have foam in them - it allows to have thinner carbon walls, and thus lighter frame. But those are very delicate and fragile frames that will not suvive any dents. Modern tech moved on to better weave and layeribg, so it isn't a thing any more.
The thing that I'd be more worried about was isolating (if it's even possible) two critical areas inside the frame where you do not want to see this stuff infiltrate, the head tube and the crank tube. It's been many years since I've taken a bike down, but I can't imagine that things have changed so much that there are no longer bearings in those areas. Bearings that probably function best when they're greased instead of having some kind of expanding chemical that does zero to keep those bearing surfaces properly lubed.
You should fill your tyres with expansion foam istead of bike sealant in your next video to see what it is like and if it is better and more puncture resistant
You might get slightly less ringing and harmonics, to make the bike feel more solid and less buzzy and fatiguing, like the Berd rope spokes. The foam does provide some vibration damping. They do this on cars from the factory, definitely works. However specialized foams do this much better, like vibrocore. What works even better for vibration damping is wood. I hammered some wood dowels and rubber into handlebars and the vibration reduction is substantial on both an mtb and a motorcycle. On the motorcycle the difference was undeniable because the mirrors were substantially clearer from the lack of harmonic vibration. This adds virtually no weight. I've not seen this suggested anywhere online, but it definitely works and is quite easy, reversible, and not messy. Tiger woods played with wood dowels hammered into his club shafts to make them less fatiguing on the hands. Also, despite many other high tech materials being tried, wood is used in virtually all alpine skis, because nothing damps vibration as well.
I came here to say the same thing. Weigh the can that you used and then compare it to a new full can. The difference would be how much weight you added to the bike.
If you want to know the added weight it's easier to just weigh in the full bottle of foam and then test it post application, the difference is all foam inside the frame!
Yes, yes, yes. Back in 1985-86 as a kid I had a Kuwahara bmx that me and a couple of friends used for lake jumping. I filled the frame with expansion foam, tied plastic bottles to the bars crossbar and pumped up the tyre as hard as I could. Good times.👍👍👍✌️🇬🇧
Forget noise, what about comfort? I think a better test would be to fill your handlebar with foam (to see if it absorbs more vibrations like other vibro-core stuff).🤔
Spank makes a foam filled gravel bar, so you're onto something. I have one, but put it on over the winter last year so I didn't get a back to back comparison to the original road bar.
Majority of those spray cans instructions say you can only foam 4 inches thickness at a time, otherwise they don't set and it turns back to liquid. Seems like it worked in this case possibly because it could get air from both sides of the foam. I had to fill a 3ft deep downward pipe and 1 can filled it, went back the next day and was just liquid in the bottom, 4 cans later and it kept doing the same thing. You need 2 part liquid foam, that stuff actually works.
I always thought the foam was designed to keep loose internal cables from rattling - problem you don't have, obviously. In any case, as an audio engineer, I'd hypothesize that the consistent reduced loudness measured in the rock garden is due to less resonance of in the tube being transmitted to the SPL meter mechanically rather than through the air. You should be able to set the SPL meter to measure using a slower average and thereby reduce the influence of the anomalous loud sounds like rims pinging on rocks.
I tried this on handlebars once.. I was trying to replicate the Spank foam core bars. The outcome is that it never dries. On narrow bars that are only 800mm long at most… it doesn’t dry so your frame is most definitely not going to dry. That said, foam is similar to gorilla glue. If it comes in contact with water it cures rock hard. So you could inject water theoretically to cure it. But then it would be hard and negate the original purpose of dulling vibrations. I did conclude that my aluminum bars were more comfortable to use. I had less fatigue and they felt more similar to carbon bars. That all said… if you do decide to try this on your bars or frame it is absolutely crucial that you spray a small amount and wait till it dries .. then spray a little more… repeat. As for weight, it will weigh more over time as it is open cell foam and takes on moisture. How much weight it will take on depends where you live. If you live in Arizona it probably won’t matter. If you ride in the Pacific Northwest and ride through puddles… you’ll eventually regret your decision once it becomes waterlogged and your 5 pound frame now weighs 10 pounds.
What would be interesting would be to do before/after for vibrations to see how stiffness/compliance changes from the foam. Not that you necessarily want to do this on another bike.
I remember doing this years ago to quiet a lug pin in the top tube that had broken off in a really old Raleigh, 70's vintage. We tried trying to shake it out but took just a bit of foam, letting it dry and it worked perfectly.
I am thinking if maybe you have an old creaky frame, this could be a way to quiet it down until you can save up for an upgrade? That would be an interesting test, to do this with a more well used frame or.older frame or something.
I’m curious if the foam made the resonant frequency of the bike lower. It would be interesting to see that. If you do decide to do the test again I would recommend possibly using the 2 part mix expanding foam. Maybe sacrifice another Kent travail for science
With using spray foam from a can, I'd have some doubts if all the foam is actually 'kicking off' or expanding. I tried to fill a container once with the intent of cutting it apart and using the foam as a mold for a leather project but found that even after a week, the foam, which was 4" thick in places hadn't expanded and had remained gooey. I later was told that some foam takes humidity or moisture to cure. On another note, as a kid, a few guys had built a ramp along one popular swimming hole. Kids would run down the hill, off the ramp and flip the bike into the creek. The water was about 15ft deep there and many bikes never got pulled back out. After a buddy lost his new bike in the water and required finding someone who could or was willing to dive down to get it, he started wrapping the frame in foam in hopes that it would float. It sort of worked but it would still sink if you didn't get to it fast enough. His dad worked at a place that used two part spray foam and one of the guys filled his bike from the seat tube. He even filled the handle bars. The next morning the bike had foam busting out of all points, it was coming out of the headset, bottom bracket, and every tiny little hole, it even had a massive foam tumor formed under the seat. After tearing the bike apart to clear the foam out of the headset and bottom bracket, and trimming off the dozen or so foam spaghetti trails all over the bike, he proceeded to 'test it out'. He launched it high off the ramp and let it land in the water. It disappeared for a bit but floated near the surface, but was still submerged a bit. It was floating upside down with the tires being the most buoyant. It worked but after a few months of that, the foam started to hold water and the bike gained weight fast. The foam apparently broke down over time and was no longer completely a close cell foam so it became like a sponge effectively filling the frame with water every time it got dunked. We realized this after seeing the bike leave a massive puddle of rusty water each time the day after it went for a swim. Eventually, it ended up at the bottom of the creek for good where it likely still rests now roughly 45 years later.
My experience with expanding foam in enclosed spaces is that it won’t expand or harden as it could if it was in an environment that that allowed moisture to get to it. From what I remember the foam used in its proper way being sprayed into a wall or other cravice in a building lets moisture still access it which is part of the curing process. Spraying some of these foams into a plastic bag or air tight concealed area will not enable it to actually cure. There might be special types with two components to mix before use that could be used in this way, but this should be tested.
I had a Canandale Raven and they actually sold a foam kit that you spray into your bottom bracket to stop it from cracking which was very reassuring, But it did make a very hollow sounding carbon bike a bit quieter.
I used to shoot it into steel frames down the top and bottom tubes through the headset, into the seat, bottom, and chainstays through the bottom bracket, and into the chainstays through the rear weep holes to keep moisture out of the frame for deep creek crossings etc. seemed to work.
For sound pressure measurements . a difference of 3 Db is significant because it is a logarithmic scale this means if a sound is reduced by 3Db it has actually 100% less energy if it is 6Db less it means it is perceived as half as loud . Thus a consistent 2 DB noise reduction can be considered as significant but only if a background noise calibration was done to know what is the normal level of ambient sound .
from an acoustics standpoint: the empty body/frame will resonate with certain frequencies and thus amplify them. It being essentially thin pipes, they dont resonate much, dont know about the material yours is made from. Also the frame isnt a uniform shape or even a voluminous body (see guitar), so the amount of possible resonating frequencies is less. The dB meter was set to dBa, which is a perceived volume. The human ear hears different frequencies at different volumes. So the first test just could have had some random rock or jiggle make a higher volume in the 3khz range. Around 3khz is the most important part for understanding speech, so the ear is more sensitive to that, which leads back to the dBa setting on the dB meter. When you filled the frame with foam, you acoustically made it a solid body. That body not being just a single material affects the resonance very much, especially when its filled with foam. Foam has a lot of air bubbles, different sizes, shapes, etc. Meaning it is very good at dampening sound. TL,DR: Foam DOES dampen the sound
I am not a bike enthusiast or expert by any means, just an overall tinkerer, but it seems to me that you could utilize a very thin walled bike frame (of whatever material is the best choice) and also utilize appropriate rigid foam to both make the bike lighter and more rigid, as well as running "conduits" inside that keep the wires free, but much quieter. I am thinking something built from the ground up, not retrofitted.
Love that you made a video about this, I am new to mountain biking and am loving going through and watching all you videos while at work, your flip bike videos actually inspired me to get an older bike and put modern components onto it for my first bike. I was looking at the SPANK vibrocore handlebars and wondered if you were to use expanding foam into other handle bars if it would have similar results to the vibrocore.
I can say. We fill hollow panels in our off road vehicles with expansion foam. To stop rattles. It's good for sound dampening and stops rattling. Also people who put loud audio systems in their vehicles use expansion foam. To stop body panels from rattling from the bass frequencies. But in a hollow bike frame i can't see it being any type of advantage.
I have done this on car 20 years ago, filling the empty of the boxed area under seat and door. Make a big different both on sound deadening and handling. Now learned it also work on a bike👍
Some things to consider: With how the video is edited, it's difficult to tell if you kept the decibel meter installed from the unfilled run to the filled run. If it was removed, and re-mounted, it's theoretically possible it didn't wind up as snug, or in exactly the same place, which could skew the results. Because decibels is a logarithmic system, a difference of 3 decibels is a doubling of volume. We don't subjectively perceive it that way, it's only about a 25% difference to our ears but.... energetically speaking, that's half the sound it used to make. Still, that 2-3db difference is pretty significant, actually. Expanding foam dissolves in acetone. I don't know anything about composite frame bikes, but anything made of aluminum should be unaffected. You could just pour acetone down the same fill hole, and slosh it around a little bit, and all the foam would pour out easily.
If you really want to do this, there are foams designed to harden in completely sealed conditions that can be used to stiffen automotive frames. Use one of those instead of contractor-grade "I can't be bothered to cut the insulation to the proper size" foam. That said, the before and after drop tests sound identical to me. I have good hearing and hi-fi speakers, and I can't even hear any specific frequencies that are quieter than before.
As you said, it's not scientific, but some randoness can be taken out in future "experiments": #1) remove the chain, cassete, RD and cables; #2) paint the stones, so that the line is almost always the same; #3) Try to secure the brake cables #4) verify the pads are secured and don't rattle Also, I would advice placing a plastic sleeve inside the frame, and inflate it. This way the foam won't be in direct contact with the material.
One big thing that comes to mind that this would be useful for would be steel frames and preventing rustout. Assuming the foam will help block moisture. Also I feel like a more fair test for sound would be an cheaper older bike. neat test
![BLACK BAG - Official Trailer [HD] - Only in Theaters March 14](http://i.ytimg.com/vi/Du0Xp8WX_7I/mqdefault.jpg)
Keeping the brake hose and cables isolated and warm in this cold times shows how much Seth cares about his Bike.
INSULATED
INSULATED
INSULATED
INSULATED
INSULATED
I saw everyone else that said this, I just felt left out.
Hey Seth, due to the logarithmic scale by which dB is measured, a reduction in 3dB is the same halving the noise output. However for the same reason and as you discovered, it is almost undetectable by the human ear.
So from and Engineering perspective this is a massive success, but practically all you've done is make your bike slightly heavier. 🤭😁 take care bro!
Finally someone else who was like how did he gloss over this
Correct, 3db is barely perceptible to the human ear, even in a side by side comparison. I'll guess the extra 300g he added is more noticeable.
The biggest contributor to “noice” on any bike seems to me to be the “loose” items on a bike and the resonance of a a securely welted or molded, essentially a one piece frame. Chains have notoriously been the source of noice on bikes. If frame resonance is a bugaboo, I would suggest inserting another type of foam! Regular poly foam! This stuff is not only easier and cheaper to install, just stuff it into the cavity but it is also easily revers-able! Just pull it out!
Seth, I would like to see an episode where you do this! You do an episode called “STUFF YOUR BIKE!” Stuff every nook and cranny with polyfoam@ handlebars, head tube, down tube, seat tube etc.! Let’s see the results!
Good job!
To be more specific, -3db will halve the sound intensity and vice versa adding 3db will double the sound intensity but how human hearing perceives sound is different. You need to add about 10db to double the perceived sound volume and about -10db to cut the perceived sound volume to half.
@@sakusaaristo191 pretty sure that's what I said. Did you read my entire comment, particularly that bit about it being almost undetectable to the human ear?
Back in the 80's expanding foam was used to add permanant bouyancy to kayaks at either end. Issue was that it tended to absorb moisture and got heavier over time. I never used it and don't think I will be filling my bikes ant time soon!
They have closed cell expanding foam now that does not absorb water.
@@bobbyhempel1513 you said "now".
Do you know for a fact that closed cell expanding foam wasn't a thing in the 80's? Or did you just mean that it exists nowadays without making a statement about the 80's?
@@Jehty_ probably the latter
You can get weather resistant foam, but yes closed cells foam tends to be more durable for weather, but at cost of weight. Still, half a can of foam is still only maybe 300g?
As opposed to termite time soon?
I use these products in my trade from time to time. Construction to be exact. I have seen these foams bow windows and doors and lift bath tubs of the floor and crack fiberglass when not used correctly. So I see why people might be worried about cracking a bike frame. If I was going to try this (which I don't think I ever would haha) I would definitely look for the minimum expansion variants designed for windows and doors. I applaud you for trying this for us, in the name of science haha.
zatz becoz you are in meriguh and yo build walls out of woot, here in germany zis foam would start to cry and would get qnokked out by aur solid konstruction!
lmao
to be honest, yeah there is lots of power within that foam. but i couldn't imagine the foam is as strong to damage a serious bike frame. interesting video tho!
edit: talking about alu / steel frames. don't know how it would impact on carbon frames. i have none, but i guess i would not not try it out on a carbon frame. :D
Good thing about homes is that they must be heated to at least above freezing temperature at all times, for any number of reasons.
This is not how bikes are used.
So you have this closed cell foam, but let's say a little bit of water finds its way into the outermost cells. Then well there's no escape. Eventually it freezes, bursts the cells, and finds in deeper. 10 years down the line you have the whole foam taking on water, perhaps not entirely full of it, but holding onto a small amount.
If you have a steel frame, it's probably rusted through at that point.
Carbon fibre... well it has some inherent water wicking ability and also suffers from water but it just makes it structurally less sound with heating/cooling cycles, little by little. The epoxy resin in carbon fibre can conduct the tiniest amount of water, but in general it's pretty resilint to it, but once you add glass or carbon fibre it happens to outright wick water in and concentrate it on the fibres, up to about a handful percent. If you forget to preheat a circuit board and carefully drive out the moisture, when you hot air solder, it's probably going to form a steam bubble and pop, which is very bad, it destroys vias. Carbon is similar.
Next, we need to see the tires filled with foam. Now that would be interesting.
Foam tires have been around for years, but they are vastly inferior to good old fashioned pneumatic tires. The only advantage they have is that they can never go flat. The disadvantages are increased weight, increased rolling resistance, and a decreased ability to absorb shock.
This foam would just crumbe to dust very quickly.
expanding foam in tyres will eventually disintegrate, so no its not as good an idea as you would think. Gander Flight has some videos showing it being done on his channel that may be worth a look
Stop using expanding foam on your bikes period. It's dumb and you're dumb if you do it, enjoy adding 5kg to your bike when all that foam soaks up any moisture
how about filling the rims?
You can still calculate the weight if you have the leftover can (and the excess foam you played round with)...
Weigh a full can, weigh the used can + foam from the clear tube etc... The difference is the weight you added to the bike. (The foam does not change weight when it expands).
Not really, there's loads of moisture lost during the curing process so the final result is much lighter than the initial weight.
@@anthonymorris8891 soooo pump out 50 grams of foam onto a piece of cellophane on some good kitchen scales... and weigh the result when it's cured.. and do the math... You can STILL calculate the weight... I just didn't want to mansplain too much otherwise I tend to write 1000 word essays... (I've reached the U-toob comment limit a few times now...)
I don't think it is correct that it loses moisture. Foam doesn't dry, it cures. Meaning the moisture isn't water that evaporates, it's foam that hardens. In fact, the instructions on the can say to mist it with water to speed cure time. I think the above measurement process would get you close.
Of course, we'd have to test it to really find out.
@@JJ-iu5hl Depends on the foam. If the medium is an evaporating additive... If the CO2 to make the bubbles requires water (than then dries) etc.
Why not just weigh the bike before and after?
You need an 2 part structural expanding foam. This will set inside the frame and doesn't absorb water. It also makes the frame stiffer. The spray stuff needs air to set, so it will never fully set in the middle of the frame.
Bring this man a beer!
Sometimes we would use a 2 part foam for setting posts in the ground. It was impressive. Expanded like crazy.
Thet do this in the chassis rails and sills of racecars for stiffness
thought this too
“Air set” well set by moisture in the air.. a couple spritz of water inside the frame will solve that issue.
Motorcyclists used a form of expanding foam for a number of years to deaden the vibration in handlebars... They also filled their handle bars with sand, and a few other vibration mitigation techniques over the years (not all at the same time). Filling the frame with foam will add weight, but it will also deaden vibration, and will help to keep the internal cables from being slapped into the frame (a potential source of noise). outside of that... minimal gains. I MIGHT consider it on the handlebars for a touring gravel bike.
I've done it. For the super light frames it can make a huge difference in noise. Particularly the ones with thin and flat sections of carbon layup that tend to act as a sound board. The downside with gap filling foam (Polymethylenepolyphenylisocyanate, propoxylated glycerin polymer) is that it stays kind of rubbery and doesn't adhere to the inside walls as well as you might think. A better foam would be something that cures firm like polyurethane. Pretty sure gap fillers used to be the polyurethane variety, but they tended to expand with more force, crushing window and door frames.
Empty your pocket on super light frame. Undo the investment by adding insulation? 🤔
Just add water (steam) when injecting to get it to catalyse without air.
If you're filling your frake full of foam then you aren't doing anything right.
I absolutely guarantee you the people doing this are probably obese and have never worked on weight savings on themselves. What a pointless type of rider.
Also you obviously never ride in any type of weather other than a dry sunny day too, or it'd take about a week for all this shite you've emptied in your frame to become soaked with moisture just like what they used to do with kayaks to keep them buoyant until it'd absorb all water. You can sound deaden with correctly placed pieces of tape, all you did was add weight to the bike because the internet told you so.
The hollow bike frame might act as a wave-guide and direct sounds and impacts from one part of the frame to another. For example, internal sheathing around the cables inside the frame, rattling against the side of a tube near the bottom bracket, might be directed up the the seat tube and closer to the decibel meter. Sound also propagates faster through solids as well so by filling the tubes with foam you dampened a lot of those higher frequencies resonating through the frame and cavity resulting in it being more "dead" (as you put it) sounding. Those dead sounds you hear are just the undamped low frequencies that have a longer wavelength and, interestingly, they remain as loud as they originally were but lack the "sharpness" that the same noise had before you neutralized those higher frequencies. It's sort of like leaving the volume on your old school boom box at 10 but pulling down the right 3 sliders on your equalizer. You get more muffled sound and the perception that you added bass even though you didn't.
Just a sidenote, I assume you read enough of reddit to know to use closed cell foam but it's worth mentioning that Great Stuff expanding foam is "closed cell" which means it won't absorb water when you do that stream crossing. Heaven help anyone who finds themselves in the middle of a long ride, a frame full of open cell foam and a bunch of water obstacles. Might want to pack an extra Clif bar for that one.
I work for an insulation company and we use spray foam insulation .It weirdly adds slot of strength to a home .It may strengthen the frame as well as dampening shocks slightly but the foam you used won't really do much because how thin of consistency the foam is.
Yup, you can build for example a DIY strong but very lightweight truck bed camper using spray foam.
They use a different foam to fill rally cars chassis and things like that to add rigidity.
It is not remotely comparable but BMW used foam back then on the e46 as a fix to prevent the subframe mounts from cracking.
Bianchi used, or maybe still does, fill the entire lower half of their high end road frames to "stiffen" the Bottom Bracket area of the frame. I first learned of this information around the Pantani era.
Yes indeed. You remember correctly. Came here to say the same. From the Bianchi Canada archives......
Technology Solutions Structural Foam Injection is a 2-component non-toxic foam developed by Henkel Spa Surface Technologies and patented by Bianchi for specific cycling applications, i.e., as a tube strengthening material.
The results obtained through the introduction of SFI have been noteworthy: a weight increase of only 20 grams yielded a 15% improvement in stress resistance, while resistance to fatigue doubled in the bottom bracket area.
All this was made possible by the special properties of this foam, which is able to distribute the loads evenly, avoiding fatigue build-up in high stress areas and in welded parts whose composition has been thermally altered.
So a hack i used to do back in the day would be filling my handlebars with foam. It damped the vibrations by like 5x and made the small bump chatter wayyyy more bearable on a long DH day.
Now that's a good ideia!
What kind of foam? This seems like a good idea that's more viable to try for home mechanics.
I know moto guys used to fill the bar ends with lead shot to absorb vibrations. The foam idea sounds like fun to play with!!!
@@nukleyar Any foam can work. it just varies in ease of use and how much dampening. Pool noodle foam is easy and cheap to cut up and insert but doesn't dampen as much as filler foam like Seth used here.
I've done this as well -- even on my Fasst Flexx bars where the elastomers already help isolate vibration, I was able to notice a small difference in reducing sidewalk buzz from riding on pavement.
The Fasst bars made A/B testing easy, since I could put something in one side but not the other and compare the difference in feel in realtime.
What I used was 7/8" closed cell foam backer rod -- the size is almost perfect for staying in place in a handlebar and has the added benefit vs. expansion foam that you can pull it back out later if you want.
To get it to go all the way in, you can use a thin rod to push it (kind of like loading a cannon).
I mean there’s definitely something to it. Spank makes a bunch of mtb parts such as wheels and handles bars which are filled with foam in order to achieve better vibration damping, by all accounts it seems to work for that purpose. So if anything a good thing to think about next time your testing is whether or not the bike soaks up vibration better during a long sort of xc ride.
I used to work at a factory where we made spray foam. Although I'm sworn to secrecy about some things🤣🤣 I can tell you this. Today's spray foam has a closer consistency to plastic than actual foam. We used to clean up spills with acetone because it breaks it down and comes right off before actual expansion. It will continue to expand even after you think it's done
Seth-
Klein bikes used to ship their beautifully painted fuselages (frames) in a box filled with expansion foam, they had plastic type bags protecting the frame from the sticky stuff, very shipping company proof when sending them around the world, not as environmentally friendly as (edible) corn starch packing peanuts, which dissolve in water.
Gregg
Seth, seth, seth, seth, and the chant goes on, read my other relative post
The foam is polyurethane foam and requires 2 things to cure: moisture and ventilation. The foam they use in cars and such is most likely blended to cure inside closed sections, that's why the inside was still gooey when you removed the tumah. It's likely the foam will take a while longer to full cure, removing the cover plate to let it "breathe" might be a good idea.
I recently used some of this stuff to surround a copper pipe coming out of the wall. I was shocked to see how long it took to fully, cure/expand. 24 hours later I thought that of course it would have to be done by then, another 24 hrs later it had expanded even more, I was like what WTH?! I wonder if it will ever fully expand in his bike. When he was waiting for it to expand around the tennis ball I facepalmed so hard I hurt myself.
This is true. It is carcinogenic so should only be sprayed in a well ventilated area.
@@dtz1000 the air your breathe is carcinogenic. Theres a difference between something being rated as carcinogenic and actually BEING carcinogenic
@@dtz1000 all the world is cancerogenic. You hurt your nail? Congrats, it's cancerogenic.
@@Sharpless2 Your antiscientific comment is carcinogenic.
You need a real 2 part foam that is designed for filling structural frames. You will see a large difference in not only less resonance, but I would also expect a notable increase in rigidity, and that should change how the bike handles. Get two identical frames and fill one with a quality 2 parts frame filling foam, and get it filled to the brim in all areas, then run a side by side. Filling tires would be easy too with another 2 part foam that is designed for repeated compression and high rebound.
i think the military tried it in tires but gave up.
You've really only filled the down tube. You would need to somehow fill all of the tubes to fully test any true differences. Also, the base frequency is likely the change you feel.
I remember, from an automotive noise class I took, that there are certain frequencies that are "comfortable" (to simplify the long explanation) for humans. And adding deadeners to the metal changes those frequencies.
I had to go and look it up, but "Natural Frequency" is the term I was looking for when I said "base frequency".
I was just going to comment natural frequency but then I read your whole post. Come on Terry you know better, read the whole thing.
Yes, full spectrum should be recorded and compared, but that's very hard to do replicable test...
Dear Seth. There's 1600 comments, so this may have already been said. There is an expansion foam solvent that you just spray on, and it dissolves it..
no, just no.
Seth spec
Yes
I agree
y do u get many like? i no know
Yes
As far as breaking frames, a few things:
The RED can is for window frames and has low expansion pressure (and low expansion in general) so it will not damage or warp the window.
The BLACK can (big gap filler) is high expansion high pressure and absolutely will create enough pressure to break things - though probably not a carbon tube.
As someone else mentioned, these single part foams use air to sure and the red can will not cure in large sections of more than an inch or so. The black can cure at up to 3" or so.
Using foam is a legitimate way to strengthen and stiffen things (and deaden sound). Hockey sticks for example use foam in selective locations and densities to tune the stiffness of the stick. There was a steel bike seat post with super thin tubing that was filled with foam in the 90s (and one frame filled with pressurised nitrogen too I think).
This could be something interesting to keep trying out, however you'll need to do more research in getting the correct type of foam (try "smooth on" and boat building websites for info). You need something with a 2 part chemical cure, low density, high expansion, low to medium pressure, and closed cell for no water absorption.
informative. thanks
The blue can is for windows
@@Stevesbe They have a few variations of course, I have the red cans right next to me, used them on my windows. The red is for larger gaps, blue for smaller, but they are still both low pressure low expansion.
I used the black ones for big holes, and it moves plywood, drywall and door jambs if you put it in the wrong spot.
I've done a similar thing with packaging foam. Take off the fork and that will usually give you access to the down tube, then fill it with the packaging. The nice thing is that it's reversible. Works well.
You should use a 2 part structural rigid foam, you can pour that and it'll expand within the tubes - if you're going for every last gram you can thin the walls on your tubes down a little (the real reason you hear some race builders have done it, rather than the ones they put out) because the foam helps with buckling and impact strength, as well as a bit of damping.
Often the same is done with cars in the a-pillars and sills.
Yeah it works, but insulation foam isn't really suitable.
I would be surprised if the foam ever even dries deep down in the center of the frame. I've used alot of spray foam in construction over the years and if it can't get air it never actually dries to become foam. It turns to a permanent orange gel of sorts.
It needs moisture to harden
@@dirkg.950 Not Moisture. But Air.
@@lossantoscity3249 not air, but moisture. Concrete is also like this, since it’s a chemical reaction taking place and not simply drying, you need all the reagents present for it to complete
Yep, I've found uncured foam that was years old. Usually from someone trying to fill too big a gap all at once.
2 dB at that is actually a pretty decent difference. Not that it was especially scientific test.
In SAE CSC we were excited to get 1dB difference in a J1161 sound test after a component change. The decibel scale is logarithmic which is another important thing to consider here
Do a follow-up where you fill your handlebars with foam and compare them to factory-filled handlebars and carbon ones :)
Would like to see the effect on aluminum handle bars
You can buy foam filled handle bars off the shelf (Spank spike 800 vibrocore). It's meant to reduce vibration they also have carbon wheel sets with a foam filled section
@@richardprust3366 I know, that's wh I asked him to....
@@Checker201lol already done by others, it works. prob more important than the frame for comfort, but less for strength.
I just installed new foam rubber handgrips. They are great for a rigid bike.
2 things, I have heard of doing this for cable noises, my reaction is do they not know jagwire foam sleeves for cable housing, 2nd I do recall Bianchi doing this on one of there road bike in the bb ,added strength supposedly???
This is a little off topic, but I have found the greatest noise reduction move on my was switching to Onyx Racing hubs. They are kind of expensive, but completely silent. Most people like the bzzzzz sound of high end hubs. I used to as well until I started using these. Aside from being silent, they also have instantaneous engagement which I love for technical climbs. They are heavier than most comparably priced hubs, but I think their silence and engagement makeup for the weight.
I find those super loud bzzzzzz hubs very annoying TBH. Unnecessary as well.
I really want those silent onyx hubs. Loud hubs are great but silence is amazing.
I've used it on an older frame to quiet down a piece of a rivnut that fell in the downtube. No openings at the bottom bracket or head tube. Worked fine, no issues, though the bike did have external routing.
I was surprised you didn't weigh the bike before and after, but thanks for *expanding* our knowledge!
I enjoyed the video. A little over a year ago budget restraint we bought the mongoose ledge x1 and x2. Have ridden those stock since. Light trail riding. With plans to make them more capable. I believe they ran $400 for the x1 and $500 for the x2 from Walmart full suspension.
Can you try to put it in the tyres?? Would love to See it
That would be the future
That would be Sam Pilgrim 😂
Good idea, but
In my experience expanding foam is very brittle
Therefore it won't replace a tire insert
Still worth a try
We’re probably trying the tires, but oh boy… there are even fewer reasons to do that. I have an idea that might make it interesting though…
People who race unibody cars would fill the main support channels throughout the car to make the chassis stiffer in turn handle better. Whether it works or not 🤷♂️. The product is also different than regular spray foam. It is less pliable than regular spray foam. Just put the foam tubing on the housing. Or just don't do it!
Might have made more of a difference with acoustic rated expanding foam, that stuff is surprisingly effective for sound dampening, if often seen that as the biggest criticism of carbon frames, they're that rigid it's like a tuning fork. Also, I seem to remember someone trying it in handlebars as a home made spank vibrocore alternative, and the conclusion was the density of the foam is crucial, normal expanding foam wasn't dense enough for that application.
It makes sense. Even if the frame isn’t the source of the noise to begin with, the fact that it’s hollow and has its own resonance can be amplifying components attached to it. Also, some annoying sounds might not take up much acoustic energy and reflect much on the dB meter.
My question, which I suppose you answered by not talking about it, is if there was any difference in the way the frame felt to ride. Thanks for another fun video!
Interesting idea Seth. Would be have been interesting to see what effect - if any - it has on vibration. Maybe by using an accelerometer or two on the frame to record vibration profile.
I own a spray foam insulating company and for the best results you would want to use open-cell retro-fit foam. It is designed to be pumped inside of empty, uninsulated, wall cavities using small 1/2" holes. It has the most expansion of any other type of foam. Plus, the foam we use comes in 2 parts, which mix as they are sprayen out the end of the gun/applicator.
I never thought of that. I did fill my steel chrome moly frame with helium before to save weight. It worked great for climbing. Hardly any pedaling to go uphill. The problem was going downhill. 😕
😂😂😂
I remember early 80s dirt bike riders would do the foam to dampen the vibration in their motorcycle handlebars and as a young kid we just copied what they where doing to our bmx
Seth, could you test the largest brake rotors that you can find? I've recently seen some 246 mm Brake rotors. It would surely be interesting to see, whether their performance is on par with their diameter.
Great video as always. Keep up the “scientific testing”!
Which bikes even fit those rotors safely?
@@sebastianjost I guess any if you buy the proper adapter?
Well with bigger brakes in cars. The most limiting factor is tires. If you have tires with better grip you will stop faster and more consistantly. Bigger Brakes in most cases just allow you to stop harder with more frequency since there will be more thermal mass. But then you have to consider will the extra weight cancel out the stopping power it might give.
I think most brakes have the power to lock up the tires at any time, but not heating up as fast and cooling off more quickly would be the big benefits. My nothing special MTB I always worry about overheating the brakes since I'm a big guy
I've got 559 mm brake rotors on my mtb and 622mm on my road bike😆
We played around with handlebars thinking a sudo vibracore. The problem we ran into was the canned stuff required air to dry and never really did. I'd like to see it where it's the 2 part foam that is a chemical reaction. That seemed to work a lot better but ended up just buying vibracore bars at the end. Cool vid!
2db is considerable! -3db of difference is half of the acoustic energy. Also, it is common for meters to weigh different frequencies differently, so if it sounds "deader" it may be because it has less high frequencies and thus it will read a lower sound pressure.
2db is usually the point where it'd become detectable in person with A B testing. Harder to judge based off recordings or when you can't alternate back and forth.
You need to double the power to get a 3db gain. But, you need 9db or 10db to perceive it as double the power. A 2db difference is almost undetectable, or getting to the point its detectable. Power and perceived loudness are to different things. The last goes in the psychoacoustics domain.
@@StarAD Absolutely correct. And I would add that the SLM that Seth is using has a listed tolerance of +/- 2.0 dB (definitely not a Type 1), so the 2 dBA difference observed means nothing.
The people I rode with back in the day, and myself, used to put those foam tube thingies outside our cables that run inside the frame to stop them from making noise. The thing with filling a frame with foam seems like a not too great idea but seeing as I'm not a foam expert and that there are many types, there might be one that works. Make sure that it doesn't retain water though.
I thought back in the day the cables were on the outside 🤷🏻♂️
@@daroob I'm not THAT old lol but good one, I'll give you that 😂
It does trap moisture, wouldn’t recommend on a steel frame. Wouldn’t recommend it at all tbh
It's more like plastic than actual foam. I worked at a plant where we made it. I now work at a place where it's actually used in new home construction
As someone who did car and home audio while I was in trade school to be a mechanic: I've used this product to fill in a seat on a shitbox car I had to drive home.
I think a better idea would be to get sound dampening paste or stuffing some old towels into the frame.
First on the paste: this is overkill, but you can get it for home construction and car audio installs, so a little leftover could be dicked around with on a bike project.
Second on towel stuffing: While custom GIK sound panels/bass traps are amazing, you can also build them yourself. One of the cheapo things I would do for people is if they had already hung wall art with a deep box frame. Just stuffing a bunch of old towels from a thrift store in the negative space drastically improves acoustics. You can do the same with a bike if you wanted too if you have a bunch of old t-shirts, etc or those rag boxes shops get. Plus you can continue to use your tube storage options etc AND you'd always have a rag in stock while on a ride.
Sound dampening is literally about absorption (and Sieben levels).
I’d be most curious if it has any potential long term chemical dissimilarity with steel, AL, or carbon. Otherwise I see no benefits to it and only potential concerns. But thanks for doing the test!
its extremely dependant on the specific type of polymer and composition used, but generally cyanate esters (which i believe are most common in these types of expansion foams) are protective against corrosion in steel. Al should not be of any issue at all either, no idea about carbon laminates either but would guess theres no significant issue.
Long term it can absorb water and even grow black mold.
Crazy RUclips showed me this, went from working on bikes to working on cars, I remember watching Seth’s bike hacks in 5th grade
Hi Seth, I ran your data to check to see if there is a significant difference between volume(db) with vs w/o expansion foam in the frame. I ran it through a two tailed t-test in excel and the numbers showed that the difference is not-significant. The p-value was .06 meaning that we fail to reject the null hypothesis (aka addition of foam makes no significant difference on volume of bike).
You know....I never did get to get into mountain biking like I wanted to. But, I just keep coming back to all the Berm Peak channels. Its never ending and relaxing entertainment. Love the content!
I could never get into mountain biking either, but I always enjoyed road biking. But now that I'm 52 with osteoporosis from my thyroid disease and I broke my back a few summers ago, I ride an electric bike now.
Does filling the handlebars dampen vibrations?
Mom can we have spank vibrocore ?
We have vibrocore at home
The vibrocore at home:
One thing I’d be concerned about, when water gets inside your frame (possibly through the cable ports or other means of entry) the foam will block the water from draining properly to the drainage holes. Can’t imagine having a pool of water sitting in your frame is good
it blocks water ingress
I usually look for reason to avoid expanding foam. Cleaning it up is a nightmare, especially off your hands, arm hair and almost impossible to get out of clothes.
And your pickups carpet.... :(
Every time I've ever used it, I've had to remove a couple layers of skin to get it off my hands afterwards. (I know you're supposed to wear gloves, but the stuff is hard enough to work with already and gloves just increase the PITA factor.)
I filled my racecar's chassis with structural expanding foam in 4lb density. The rigidity added to the chassis was a huge difference, I did only one side first and the car was very unbalanced from left to right corners.
now both sides done it is much quieter and the sound of the doors closing is damn near that of a luxury car.
Merry Christmas Seth thanks for the content
I like the idea of internal routing cables but it took me a few weeks to isolate the noise on my Trek Dual Sport. I thought it came from front fork when I go though a drop but it was from the rear brake line in the down tube. I did some research here on this site and finally decided to carefully wrap the brake line and insert to the frame with bubbled envelop from Amazon. It works. Now I know what to do if I hear that clanking noise again on my other bikes. Insulation foam is not a good idea IMHO.
Filling your handlebars with puddy or gel to reduce vibrations for the hands is something people have been playing around with for a while. Especially with motorcycles.
I just used light weight heater vent filters and stuffed a bunch in my Orbea Rallon to deaden the cable rattle. Worked brilliantly and super light weight, No mess and easy to remove. My bike runs so much quieter now.
You should fill more parts of the frame up like the highest beam and the steering
when you want to fill a cavity with expanding foam like you used, these things use water to complete the process so, what I've seen is using a steam cleaner to kind of inject steam through the foam can nozzle and that can allow the foam to actually fill the cavity uniformly and get a much more solid result since it has the moisture it needs to complete the process. I know there are other foams that would work without pumping water into your frame but those can be pretty expensive materials.
I wonder if this would make rear of hardtail more compliant/change ride feel. Always wondered what Virocore in bike frame would feel like.
Hard foam will make it stiffer, it is basically a 'sandwich' construction like used in boats or planes.
I think that this would actualy dampen som impact on frame and make it stronger because of air you have a thick foam pushing against it. Its like having a bone with marrow and without it..which one is better. I would do that even if it added some weight.
Might be an interesting strategy for helping guide internally routes cables that don’t have glass tubes after it’s been done the first time. If any of the cables on that bike are internal (dropper), be a gent and find out for us!
Some of the high-end bicycles did have foam in them - it allows to have thinner carbon walls, and thus lighter frame. But those are very delicate and fragile frames that will not suvive any dents. Modern tech moved on to better weave and layeribg, so it isn't a thing any more.
Fill you tire with foam you will have no flat
The thing that I'd be more worried about was isolating (if it's even possible) two critical areas inside the frame where you do not want to see this stuff infiltrate, the head tube and the crank tube. It's been many years since I've taken a bike down, but I can't imagine that things have changed so much that there are no longer bearings in those areas. Bearings that probably function best when they're greased instead of having some kind of expanding chemical that does zero to keep those bearing surfaces properly lubed.
You should fill your tyres with expansion foam istead of bike sealant in your next video to see what it is like and if it is better and more puncture resistant
Good idea, I would love to see that 🚵♂️
That would be good to watch 👍🏻 no more punctures would be a god send 😃
You might get slightly less ringing and harmonics, to make the bike feel more solid and less buzzy and fatiguing, like the Berd rope spokes. The foam does provide some vibration damping. They do this on cars from the factory, definitely works. However specialized foams do this much better, like vibrocore. What works even better for vibration damping is wood.
I hammered some wood dowels and rubber into handlebars and the vibration reduction is substantial on both an mtb and a motorcycle. On the motorcycle the difference was undeniable because the mirrors were substantially clearer from the lack of harmonic vibration. This adds virtually no weight. I've not seen this suggested anywhere online, but it definitely works and is quite easy, reversible, and not messy.
Tiger woods played with wood dowels hammered into his club shafts to make them less fatiguing on the hands. Also, despite many other high tech materials being tried, wood is used in virtually all alpine skis, because nothing damps vibration as well.
The weight difference should be easy to work out. You just need to weigh the can of foam before and after. It doesn't get heavier as it expands 🙂
It might absorb moisture over time and get heavier though
I came here to say the same thing. Weigh the can that you used and then compare it to a new full can. The difference would be how much weight you added to the bike.
5:33 might be the gnarliest timelapse we've ever seen. 😂
If you want to know the added weight it's easier to just weigh in the full bottle of foam and then test it post application, the difference is all foam inside the frame!
Yes, yes, yes.
Back in 1985-86 as a kid I had a Kuwahara bmx that me and a couple of friends used for lake jumping. I filled the frame with expansion foam, tied plastic bottles to the bars crossbar and pumped up the tyre as hard as I could.
Good times.👍👍👍✌️🇬🇧
Forget noise, what about comfort? I think a better test would be to fill your handlebar with foam (to see if it absorbs more vibrations like other vibro-core stuff).🤔
Spank makes a foam filled gravel bar, so you're onto something. I have one, but put it on over the winter last year so I didn't get a back to back comparison to the original road bar.
Majority of those spray cans instructions say you can only foam 4 inches thickness at a time, otherwise they don't set and it turns back to liquid. Seems like it worked in this case possibly because it could get air from both sides of the foam.
I had to fill a 3ft deep downward pipe and 1 can filled it, went back the next day and was just liquid in the bottom, 4 cans later and it kept doing the same thing. You need 2 part liquid foam, that stuff actually works.
Ok now that the foam is set try the liner you put in for the dropper cable. I give it a 70% chance that it's going to give you a hard time.
I always thought the foam was designed to keep loose internal cables from rattling - problem you don't have, obviously. In any case, as an audio engineer, I'd hypothesize that the consistent reduced loudness measured in the rock garden is due to less resonance of in the tube being transmitted to the SPL meter mechanically rather than through the air. You should be able to set the SPL meter to measure using a slower average and thereby reduce the influence of the anomalous loud sounds like rims pinging on rocks.
You only need to weigh the foam can before and after to work out what weight you've added!
I tried this on handlebars once.. I was trying to replicate the Spank foam core bars.
The outcome is that it never dries. On narrow bars that are only 800mm long at most… it doesn’t dry so your frame is most definitely not going to dry. That said, foam is similar to gorilla glue. If it comes in contact with water it cures rock hard. So you could inject water theoretically to cure it. But then it would be hard and negate the original purpose of dulling vibrations.
I did conclude that my aluminum bars were more comfortable to use. I had less fatigue and they felt more similar to carbon bars.
That all said… if you do decide to try this on your bars or frame it is absolutely crucial that you spray a small amount and wait till it dries .. then spray a little more… repeat.
As for weight, it will weigh more over time as it is open cell foam and takes on moisture. How much weight it will take on depends where you live. If you live in Arizona it probably won’t matter. If you ride in the Pacific Northwest and ride through puddles… you’ll eventually regret your decision once it becomes waterlogged and your 5 pound frame now weighs 10 pounds.
Most of the noise is drivetrain.
What would be interesting would be to do before/after for vibrations to see how stiffness/compliance changes from the foam. Not that you necessarily want to do this on another bike.
I remember doing this years ago to quiet a lug pin in the top tube that had broken off in a really old Raleigh, 70's vintage. We tried trying to shake it out but took just a bit of foam, letting it dry and it worked perfectly.
I am thinking if maybe you have an old creaky frame, this could be a way to quiet it down until you can save up for an upgrade? That would be an interesting test, to do this with a more well used frame or.older frame or something.
Especially on a rigid bike.
I’m curious if the foam made the resonant frequency of the bike lower. It would be interesting to see that. If you do decide to do the test again I would recommend possibly using the 2 part mix expanding foam. Maybe sacrifice another Kent travail for science
With using spray foam from a can, I'd have some doubts if all the foam is actually 'kicking off' or expanding. I tried to fill a container once with the intent of cutting it apart and using the foam as a mold for a leather project but found that even after a week, the foam, which was 4" thick in places hadn't expanded and had remained gooey. I later was told that some foam takes humidity or moisture to cure.
On another note, as a kid, a few guys had built a ramp along one popular swimming hole. Kids would run down the hill, off the ramp and flip the bike into the creek. The water was about 15ft deep there and many bikes never got pulled back out. After a buddy lost his new bike in the water and required finding someone who could or was willing to dive down to get it, he started wrapping the frame in foam in hopes that it would float. It sort of worked but it would still sink if you didn't get to it fast enough. His dad worked at a place that used two part spray foam and one of the guys filled his bike from the seat tube. He even filled the handle bars.
The next morning the bike had foam busting out of all points, it was coming out of the headset, bottom bracket, and every tiny little hole, it even had a massive foam tumor formed under the seat.
After tearing the bike apart to clear the foam out of the headset and bottom bracket, and trimming off the dozen or so foam spaghetti trails all over the bike, he proceeded to 'test it out'.
He launched it high off the ramp and let it land in the water. It disappeared for a bit but floated near the surface, but was still submerged a bit. It was floating upside down with the tires being the most buoyant. It worked but after a few months of that, the foam started to hold water and the bike gained weight fast. The foam apparently broke down over time and was no longer completely a close cell foam so it became like a sponge effectively filling the frame with water every time it got dunked. We realized this after seeing the bike leave a massive puddle of rusty water each time the day after it went for a swim. Eventually, it ended up at the bottom of the creek for good where it likely still rests now roughly 45 years later.
No ways I'd ever do this, but it was super entertaining to watch; thanks!
My experience with expanding foam in enclosed spaces is that it won’t expand or harden as it could if it was in an environment that that allowed moisture to get to it. From what I remember the foam used in its proper way being sprayed into a wall or other cravice in a building lets moisture still access it which is part of the curing process. Spraying some of these foams into a plastic bag or air tight concealed area will not enable it to actually cure. There might be special types with two components to mix before use that could be used in this way, but this should be tested.
I had a Canandale Raven and they actually sold a foam kit that you spray into your bottom bracket to stop it from cracking which was very reassuring, But it did make a very hollow sounding carbon bike a bit quieter.
I used to shoot it into steel frames down the top and bottom tubes through the headset, into the seat, bottom, and chainstays through the bottom bracket, and into the chainstays through the rear weep holes to keep moisture out of the frame for deep creek crossings etc. seemed to work.
For sound pressure measurements . a difference of 3 Db is significant because it is a logarithmic scale this means if a sound is reduced by 3Db it has actually 100% less energy if it is 6Db less it means it is perceived as half as loud . Thus a consistent 2 DB noise reduction can be considered as significant but only if a background noise calibration was done to know what is the normal level of ambient sound .
from an acoustics standpoint:
the empty body/frame will resonate with certain frequencies and thus amplify them. It being essentially thin pipes, they dont resonate much, dont know about the material yours is made from. Also the frame isnt a uniform shape or even a voluminous body (see guitar), so the amount of possible resonating frequencies is less.
The dB meter was set to dBa, which is a perceived volume. The human ear hears different frequencies at different volumes. So the first test just could have had some random rock or jiggle make a higher volume in the 3khz range. Around 3khz is the most important part for understanding speech, so the ear is more sensitive to that, which leads back to the dBa setting on the dB meter.
When you filled the frame with foam, you acoustically made it a solid body. That body not being just a single material affects the resonance very much, especially when its filled with foam. Foam has a lot of air bubbles, different sizes, shapes, etc. Meaning it is very good at dampening sound.
TL,DR:
Foam DOES dampen the sound
I am not a bike enthusiast or expert by any means, just an overall tinkerer, but it seems to me that you could utilize a very thin walled bike frame (of whatever material is the best choice) and also utilize appropriate rigid foam to both make the bike lighter and more rigid, as well as running "conduits" inside that keep the wires free, but much quieter. I am thinking something built from the ground up, not retrofitted.
I got the switch kit ad and it was like “this” “this” “this” then I skipped and Seth said “this, is foam” or whatever it lined up perfectly
Love that you made a video about this, I am new to mountain biking and am loving going through and watching all you videos while at work, your flip bike videos actually inspired me to get an older bike and put modern components onto it for my first bike. I was looking at the SPANK vibrocore handlebars and wondered if you were to use expanding foam into other handle bars if it would have similar results to the vibrocore.
I can say. We fill hollow panels in our off road vehicles with expansion foam. To stop rattles. It's good for sound dampening and stops rattling. Also people who put loud audio systems in their vehicles use expansion foam. To stop body panels from rattling from the bass frequencies. But in a hollow bike frame i can't see it being any type of advantage.
I have done this on car 20 years ago, filling the empty of the boxed area under seat and door. Make a big different both on sound deadening and handling. Now learned it also work on a bike👍
Your content has really stepped up and moved with the times, very clever. This style of content is very absorbable, and easy to watch and learn.
Some things to consider:
With how the video is edited, it's difficult to tell if you kept the decibel meter installed from the unfilled run to the filled run. If it was removed, and re-mounted, it's theoretically possible it didn't wind up as snug, or in exactly the same place, which could skew the results.
Because decibels is a logarithmic system, a difference of 3 decibels is a doubling of volume. We don't subjectively perceive it that way, it's only about a 25% difference to our ears but.... energetically speaking, that's half the sound it used to make. Still, that 2-3db difference is pretty significant, actually.
Expanding foam dissolves in acetone. I don't know anything about composite frame bikes, but anything made of aluminum should be unaffected. You could just pour acetone down the same fill hole, and slosh it around a little bit, and all the foam would pour out easily.
If you really want to do this, there are foams designed to harden in completely sealed conditions that can be used to stiffen automotive frames. Use one of those instead of contractor-grade "I can't be bothered to cut the insulation to the proper size" foam.
That said, the before and after drop tests sound identical to me. I have good hearing and hi-fi speakers, and I can't even hear any specific frequencies that are quieter than before.
As you said, it's not scientific, but some randoness can be taken out in future "experiments":
#1) remove the chain, cassete, RD and cables;
#2) paint the stones, so that the line is almost always the same;
#3) Try to secure the brake cables
#4) verify the pads are secured and don't rattle
Also, I would advice placing a plastic sleeve inside the frame, and inflate it.
This way the foam won't be in direct contact with the material.
One big thing that comes to mind that this would be useful for would be steel frames and preventing rustout. Assuming the foam will help block moisture. Also I feel like a more fair test for sound would be an cheaper older bike. neat test