Is Repaired Carbon Fibre Safe? Breaking Point Test
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- Опубликовано: 15 мар 2024
- Is it possible to reliably repair broken carbon fibre parts? Conventional wisdom would disagree, but being proudly unconventional, we test repaired carbon fibre parts to destruction. Yes, it was fun.
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Directed and Edited by Girish Appanah 
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Whenever I hear about carbon fiber safety I think of submarines for some random, undetermined reason. Maybe just me.
I think back to the one that was piloted with a Logitech remote control too.
SNL - "I squish you ... "
@@nunyabusiness7477, can't understand how so many people agreed to get in that thing 🫣
Great tensile strength. Excellent for making containers containing high pressures (trying to stretch the fiber) - Terrible for making containers taking high external pressures (compressing the fiber lengthwise, which very much would like to).
That submarine was holding up against the pressure with resin, carbon fiber in that mix was almost like pushing with a rope.
I then think about diversity hire and that they fired all capable men that were doing a good job working on these submarines and that the fired men already told them it's unsafe but diversity hire knew better. It's almost like real life comedy.
This video should be dedicated to all the Robs out there. The unspoken repairmen who fix all the things we dont know how to or dont have the tools to do so.
he doesn't know how to do it properly either. He makes sail boards not aerospace products... Not saying it didn't work, but its not proper. And hes also not wearing appropriate PPE for someone working with carbon fiber daily.
@@plav032i watched some footage from Pagani factory in TV (multimillion usd cars), no had had masks or gloves when laying down the carbon.
You dont need that but if you work daily with that I would say it would be good to have
The guy used different style weights, one spread the load out among 1ft of bar length on the repaired bars. The other put all the strain on a 1 inch section of the brand new bar with the metal weights clanking on the CF on every drop. C'mon. Completely different tests doing it like that.
I've come to expect more from this channel, Fortnine is better than this.
Glad I'm not the only one that noticed this.
the plastic weights are also not symmetrical in some drops
@@TheValdesXRyan has a degree in physics, he obviously didn't have much oversight on the testing
Yes, several big problems with the testing here. The rig isn't the same, the weights aren't the same, the rig and weights experience failures, the sample size is 1, and there seems to be a bias towards wanting to show the repair is stronger. If the script for the video is written before filming, it's not really a test any more.
The quick & dirty 3D printed PLA sand-filled weights broke. It’s a RUclips channel, not a real test lab.
That said, I’ve got a degree in composite manufacturing & repair and I wouldn’t touch those damaged handlebars without a written consent that they couldn’t be used for anything other than non-structural static display or rig testing.
I can repair a CF Boeing better than a United A&P, but I could only ever claim it to be original strength with an engineer’s instructions and write-off.
Anyone claiming that a repair is stronger is either lying or adding mass, which is antithetical to the point of the original CF part, and potentially actually making it weaker. Run.
Did you just pan past a carbon fiber Honda XR650R without letting us have a better look?
Come on fellas! Let us see that baby! Or better yet, devote an hour of your top-notch videography talking about it and reviewing it and racing it around and ultimately delivering it to me to ride around and then just kind of let me steal it and keep it and ride it forever and ever and ever...
It was BEAUTIFUL
This is the problem when they forget the audience.
As for carbon fibre, I had the miss-fortune of riding a friend bike down a reasonable hill and the rear triangle simple came apart. Not sure what felt worse, me riding a dismantling bike, or knowing the owner saw me "wreck" it without doing anything special. That was decades ago and I still have no idea how I didn't get seriously injured. Or why I might not want any carbon bits besides fairings.
Good eye, didn't even notice it, especially because they all look different by now. Hopefully one finds you someday.
I stumbled into mine looking for a first bike to learn on that wasn't too heavy and wouldn't get destroyed if l dropped it. Had no idea of the lottery l hit until years later, still my only bike and l don't think l could ever replace it
YES THAT
@@microwave221 two BRPs smile at me from my garage daily. Love these bikes!
Come on FortNine! You have been producing quality for so long, that I would hate for this new experiment to start a trend in the wrong direction. I loved the video, with the exception of the conclusion. Look, I get it that your weights broke, you may have changed bar type for the control, your sample number was low, your force measuring methodology is likely very flawed, but your conclusion was the worst part. The conclusion should be that the repair was not stronger than the other side of each handlebar in your test, and that the test rig and methodologies weren't good enough to conclude that the repairs were stronger than the new bar. You aren't known for being misleading, so I hope this sort of video gets more review before being released into the wild. Was Ryan out of town or something??
It's disappointing, and also not the first dodgy test shown on here. Hope they go back to their strengths, discussing riding motorbikes with brilliant videography. They are the best channel on YT at that, I think, but not this stuff.
@thomascook8844 was about to say the same thing and you said it so much better
there was literally another unrepaired side of the bar experiencing in theory the exact same forces when the repaired one broke so there must have been a major difference between the two tests
I agree completely , I must admit that you said it much better than I ever could . Thank you
This is at least the second video where the research and testing was either wrong or seemed misleading to prove a point. I think that we are seeing a shift in the channel now that they have taken off in popularity.
I worked as the prep and finishing person at one of the longest active carbon fiber bicycle repair shops in the USA (I won't name them). 1. NOTHING short of a frame was every repaired for a customer. We experimented on bars and rims but it was not worth it. 2. we've never had a repaired frame fail at the repair point. They got to the point at the end but this was probably the least informed or informative FortNine video to date.
That felt like a stretch to justify a preconceived point. Rob's repairs we not stronger than the original parts, but they are stronger than some other completely unrelated parts... Ok then.
If the repairs are stronger they would have held up more than the side that wasn't repaired, simple as that.
Seems like it's all subjective, especially considering most carbon parts have a degree of strength variability across the production line anyway.
Rob also just bonded a new section of uni-directional carbon tube to the end, with alot of the force concentrated on the bonding agent. A proper repair should be tapered then filled with layers of cloth with alternating weaves, then resin infused in a vacuum and cured with heat. He did none of that, just literally glued in a dowel and a tube over top.
If repairing a broken bar made it stronger, then breaking it would be standard process in manufacturing. Like come on.
@@148Reaper Stronger, but heavier and more expensive.
The repair simply uses more carbon fiber than the original part had, that is why it is stronger and heavier.
It's like repairing a hole in 1mm sheet of metal with a 2mm sheet of metal.
i hated the graph at the end with the 50 data points, unlabelled axes, and scaling "data"
I love you guys, and I watch all your videos, but the testing had too many variables. The switch from sand weights to metal weights and the failure of the testing rig could have skewed the results.
I think it gets the point across well enough that repairs to CF are worth it over replacing.
@@mbpm6135 really if anything, the missed point was in the fatigue at the end. The plain bar broke earlier because of fatigue. What is that to say that a part isn't nearing the limits of fatigue and now you've sunk money into a repair when it's going to fail again elsewhere? Yes it's good for accidental damage like whacking a tree, but not really if the rest is fatigued and going to fail.
Following this channel for a time now. I am more into the motorbikes, but carbon is everywhere, so still nice to know. However its kinda sad the quality of the testing didn't line up with FortNine usual quality. I mean, if you talk science, then really do it properly, even if you don't like the results. This it what gave this channel its twist. You got too many subs for returning to this "home enthusiast science" level.
Came for quality but the last 5 minutes of the video left me devastated Ryan please come back we need you
Cycles to failure is a very real concern for all kinds of equipment.
At my old arboriculture gig, we would keep climbing ropes completely separate from rigging ropes, even if they were identical: we wouldn't trust a 6000 lbs test rope to support a man if it had ever been shock-loaded, or if it saw repeated use. Similar considerations were taken for all critical devices.
Well done D.O.D.
Let’s hope you are talking about static ropes (although you shouldn’t really fall on those), otherwise the entire rock climbing community is laughing at you.
@@gherites I think he’s talking about trimming trees.
So if the repairs are more solid than the fresh bar, why did the repaired side breake first before the good part of the handlebar?
@@D3nn1s Maybe all that violence caused a bunch of nano cracks, fissures or whatever?
cycles are a huge deal in aviation, after so many cycles they just scrap the entire airframe.
but still, why didn't the other side break first? The additional bar you bought, was it the same make/model/year as the ones you destroyed before?
Coz otherwise you can't scientifically compare the results
That is a reason I gave a dislike to that video.
By brain went to welding. As you weld one point if done correctly it won't rebreak on the weld but further down the area due to the material being stronger at the weld but weaker around the surrounding area. I think the carbon fiber became stronger at the repair spot but since the area outside the repair spot is a weaker then it decides to break at that point.
he also didn't blend the carbon... he just bonded a dowel inside the bar, and bonded a new section to the dowel. It's only testing the strength of the adhesive he used. A proper repair would taper the existing carbon, and build up carbon layers with alternating weave directions soaked in resin and cured with pressure and heat.
@@TheAtqthe30ththat's not what they are asking. The new bar tested at the end broke at a lower force than the repaired bars. But the repaired bars at a control side that was still original condition, so you should expect that side to still fail at the same force as the new bar. Its a useless comparison and unscientific
@@plav032 Yeah, I kept waiting to see an actual carbon repair. This is just putting a stick in between the break
cutting carbon fibre using an angle grinder without wearing a mask is really not a good idea
Should be a half-mask at the bare minimum. I also use disposable gloves and overalls.
@@plav032 Agreed, carbon fiber (honestly just carbon in general) is nasty stuff to work with, especially to sand or cut with abrasive discs.
Agree re:mask. I’d go facefitted FP3. Everyone’s paranoid about asbestos and then get all blase taking an angle grinder to CF and fiberglass 😬
Totally safe if done properly.
Not unlike fixing fiberglass.
And he didn't fix it properly.
@@plav032 Thanks, rando voice from the internet. You seem legit. I'll listen to you.
@@WindFireAllThatKindOfThing lmao
Untrue. Especially for structural and technical parts.
Was it made in an autoclave under pressure and temperature ramps?
Doesnit have a crash profile?
Is it designed to fail in a specific way?
For instance a carbin race car tub.
Thats designed to collapse in a crash in a very specific way, any significant structural damage?
Its goes in the bin.
@@deadprivacyis any of what you wrote relevant to bicycle parts?
The surface of the load was different on repaired handlebars and new one. Repaired had weight distributed on more surface, around 10cm (more less width of grips) the new one had just narrow gym weight installed on like 2cm of the width of handlebar. Thats not apples to apples.
Been riding with a repaired chainstay for around 2.5 years now! I found a guy that usually does carbon fiber cars and he put a sort of carbon bandaid around 270 degrees of the chainstay. Its held up great since.
interesting topic, but I have to agree with the naysayers that the testing would have needed more consistency. In the end I expect your conclusion to be correct, repaired fiber plastic parts are at least safely usable. But the documentation and methodology was lacking and I am left unsure whether the conclusion is actually correct regarding low amplitude fatigue loads as experienced in most applications.
As someone who works with composites for a living there’s a reason why I have an aluminium ebike and not a carbon one(apart from the cost). I’m heavy and when I fails it just fails. As for repairing it, yes you can and you can make it stronger but you can just be moving the problem to around your repair as that will now be weaker than the repair.
It’s just a minefield that can be easily avoided.
The weight of the narrow barbells is located further from the center of the handlebar than on the wide barbells. so, even though the weight is the same - the impact it produces on the handlebar - is completely different
As long as the center of the weight is the same distance from the center of the bar it is not. The sand weight is wider, making it appear closer, but as long as the center of the weights is in the same place it is comparable.
Always gonna be a "nuh-uhh, no it didn't, ya did it wrong" type of whiner....
Yes. Such an obvious flaw. Ryan would not have made such a rookie mistake.
@@dugg117That would only be true if the bar were absolutely rigid and the weight was being applied gradually. Impact loading is a way different animal.
@@thomasstuart2936 it's not breaking where the weight is connected to the bar. Distributed loads can 100% be simplified to their point load equivalent in this case.
The methodology is quite flawed, I'm sorry to say. The idea is great, but the sample size is too small and the difference in weights between the repaired handlebars and store-bought version, means the comparison doesn't really hold up. Same with the breakage of the store bought bars, as it could've broken because the rig failed, instead of visa versa.
The big barbells are too wide, so the weight is distributed along a much larger area. The actual weights concentrate all their mass on a much smaller area, changing the characteristics of the shock load. Ideally, the weight is the width of a hand and is sitting on grips mounted on the bars.
This test doesn't take into account variation in production methods and brands. As 1 of each was tested, you can have a bad apple and it is always going to break. To really have an informed opinion on this, you need to test multiples of each scenario, in a much stronger rig, simulating reality is closely as possible. It also need to take into account fatigue, load at odd angles and more.
Carbon fibre parts are made in many different ways and have varying shapes, each with their own failure points. As the third broken handlebar showed, some breaks cannot be repaired. If handlebars (in essence a carbon fibre tube) can be fixed, it doesn't mean a solid carbon part can be as well. It might, but the results don't apply to all carbon fibre parts.
I understand a test of this size is way beyond a channel like this, financially, but the conclusion from this video is based on a test that doesn't really prove anything. At best the conclusion is that carbon fibre can be repaired in some occasions and can be as strong, if not stronger afterwards. It all depends on the break and the part, and definitely requires an expert.
What I find silly is that those parts are essentially injection-molded plastic with carbon reinforcements. They're not "carbon fiber" in the sense that sheets of carbon weave have been laid together like you would find in a high-end bicycle or car frame; they're fiber-reinforced plastic like the more traditional glass-reinforced nylon.
I find that confusing as the term "carbon fiber" gets thrown around a lot but now encompasses multiple manufacturing techniques, which produce wildly different results.
I know someone else has said it, but the point still stands:
The repaired end of the bars broke before the unrepaired and undamaged ends. The repair was not stronger than the original.
Where is this channel going? Serious question
idk I actually skipped thru this vid, mostly because I don't care about this guy or bicycles... the 2nd Fortnine vid I've skipped in years, the first one was another bicycling vid interview style with Ryan and some guy maybe this guy again, I don't remember but don't really care... The other 99% of F9 videos are interesting and masterful though
@@Andrew-mk7rm I agree with you 100 %. I also only skipped the same two videos in the many years that I have followed F9. It’s probably because they are selling Mountain bikes in their stores. They should really have a separate channel for that stuff.
Many bikers ride bikes. 2 wheels good..
I ride bicycles too but I do come here for motorcycle content, I skipped this one too, Im already subscribed to a few bicycle content channels.
I commute to work and do my local errands on my bicycle, it's an aluminum frame with a steel fork, it seems to work fine for me.
@@HaggisPower so do I
Due to the nature in which carbon fiber fails I've alway given it a wide berth, its alway catastrophic and almost never ends well. If I need to save a few grams I'll take a poop before the ride, if I need to save a load more, well, I'm 15kg the wrong side of a slice of cake or two, so I thing I'd be better off starting there!! An unplanned emergency dismount at 30kph with my bars in two bits is just not a good vibe!
It's not really rational though. Most of the time, carbon simply _doesn't_ fail - it's an extremely durable material, in particular it has excellent fatigue characteristics (not quite as good as steel, but way better than aluminium). And on a heavy impact, aluminium bars would actually snap just as sudden-catastrophically as carbon bars. The one problem carbon specifically has is that even very small damage (stone impacts) can trigger failure, but that's much more a problem for lower parts of the frame, chainstays and pedals, than handlebars.
If you don't care about weight _at all_ then sure, thick steel is the safest option. But that's not just a couple of grams heavier, more like _twice as heavy_ - anything that's similarly light to carbon bike parts will also be similarly fragile.
@@leftaroundabout What do you know about Ti?
@@garysarratt1Titanium combines to some extend the advantages of steel and aluminium, but it doesn't really change the picture: carbon is still superior in strength/mass. I suppose you could overbuild a titanium frame to be as sturdy as an overbuilt steel frame while not being quite so heavy, but it would still have to be much heavier than a typical carbon frame, and probably more expensive too (titanium is very difficult to work with).
@@leftaroundabout I didn’t know if it can be a direct replacement, mass and size wise, for another metal or carbon. I do notice it seems bulkier, but is the weight & strength good enough for me to opt for Ti next time, or Al or carbon. I’m older than I used to be (what a dumb thing to say🤦🏼♂️), but nearly 35# lighter and better cardio. I can afford any of them, but don’t throw money away if I can help it. Just trying to cut through fawning reviews and ads to buy once, cry once.
@@garysarratt1well, I don't own any titanium bike, so I can't really say how good it is in practice. It is quite possibly the best-compromise material considering strength, durability, compliance and corrosion resistance. No doubt it's a good choice for a gravel/touring bike. But whether it's worth the hefty price tags is questionable.
I think that objectively, titanium only pays off for specialty applications where you need either strength at extreme temperatures or chemical/biocompatibility. Neither is relevant for bicycles.
that episode has a good Mythbusters vibe. With less explosion. :D
LOL, I feel they're slowly working up to things that go boom with their awesome videos. I liked the recent truck one, science, sports and fun. Great combo.
But similar destruction! :)
And a similar level of scientific rigour...
I knew there was something missing in this video. Thanks for pointing it out.
This seems to beg the question if Rob repaired a broken new stock bar, would it break at below or above the original strength?
It'd be nice to assume that Rob can repair any carbon fiber handlebar to ~3500Nm break point, but given that his repairs were worse than the originals, it doesn't seem likely. It was nice of Rob to participate in the video but I think it's a stretch to conclude you should repair your new stock handlebar.
Also, the dots are pretty but where are the axis labels?!
I think the test didn't support your premade conclusion so you added some data that would support it. Anyway, the video runs the risk of reducing trust in the brand imo because it's shot in a style that uses the scientific method while simultaneously ignoring it.
@@zachlevyYea I have concerns as well. I've seen others seemingly mimicing Project Farm's style of garage testing, but you have to include all the steps. an
Making a semi-cameo here is Rob's killer vintage Bronco - that's its fender he's working on in the opening.
The weather at time of filming and the fact that Rob's Bronco doesn't have a top prevented it from having a starring role in the opener!
-D.O.D F9
just seeing a shop with that much carbon dust around makes me uncomfortable... great that there are some individuals out there who are able to save those broken parts from being scrapped :)
Mad respect for the Evil Dead 2 reference.
groovy.
I heard somewhere that particles from repairing (sawing/sanding) carbon fibre were pretty dangerous to the lungs. ? Nice video 👍
Oh shush, now Karen....
@@jamesonpace726 not at all. They arr lethal.
The dust never breaks down and sits in your lungs til you die.
Same condition as silicosis which is why sandlblasting with actual sand is simply never done by anyone with any sense anywhere anymore.
Nor is chopping or sanding fibreglass without respiratory protection, preferably a fed air setup.
Yes its extremely carcinogenic
It is extremely toxic. NADEP experience speaking.
To add to my doubt, you can´t test that simple how the repair holds up to stress, fatique and strain over time...
Yes. Just go ask Boeing. It’s harder to tell if all the carbon fibre filaments are bonded properly- there doesn’t seem to be much “give” in C-F. Metal flexes and eventually goes ping. C-F holds and then goes “sprang”.
They had some issues with C-F fuselage joints.
Manufacturing defects.
Well, you tell the fine repaired part is broken on 3500, but new on 2500. BUT on the repaired part was the second undamaged side that endured 3500.
So, in fact, one bar survived on 3500, another is broken on 2500.
It seems, that all is a crappy lottery.
The repair method was different between the two parts. That's why one is labeled Rob's fancy method and the other Rob's quick and dirty method.
I learned about carbon fibre breaking last year
The graph at 10:30 has me scratching my head. what does the X and Y axis represent here? I feel like this XY plot should have been a bar graph
No longer relevant.
This channel has devolved into clickbait with obviously flawed "tests" to stir up controversy and stimulate engagement in the comments.
It works for F9, but I hate it.
Unsubbed.
@@stevenkelby2169goodbye stevenkelby !!!
@@stevenkelby2169i really don't want this to be true!
@@NickElliottuk Me either but I think it's inevitable in capitalism.
there's also about 50 "data points" from 4-5 drops of a handlebar. it's bogus
I repaired a Downtube headtube junction on a full suspension trail bike. Rode it a few more times and it broke again but on a chainstay pivot, so the whole “if the repair is better than the rest it will break somewhere else” has been true for me.
I've had a few carbon wheel rims come into my composite repair workshop. Buggered if I was going to repair them as instantaneous catastrophic failure, followed by a face plant, is a good way to lose friends.
The comments about proper scientific methods have their place here, but may I be one to say thank you for trying to showcase the merits for repair! Carbon fiber is in our lives now and I love that Robert’s Composites is here in our front yard. If you broke something expensive, or it was part of something larger, repair should come to mind. Just because it isn’t perfect doesn’t mean it’s irrational. Customers of Rob will understand!
"Repaired carbon fiber can be as strong or stronger than a brand new product sold for the same purpose." -- While this concluding sentence is correct, I feel like it's shifting the goalposts a little bit. The repair is not as strong or stronger than the original. But it is stronger than another non-repaired but unrelated product.
I agree with this assessment with the exception that your conclusion assumes that test A and test B were of sufficient parity in all variables. The constant failures of the test rig and lack of retests or documentation of potential variance introduced by alterations of the test environment leads me to conclude that a whole host of unmentioned confounding variables were just completely ignored to fit the script's narrative. Product safety testing is not entertainment and no attempt at disclaiming liability can change that. So much of this video isn't just moving the goalposts, but doing so without disclosing how and where they were moved. They presented accelerometer readings with no explanation of how accurate they are, or how they are actually useful as a measurement. The final obvious issue is that when we ignore forces, brands, and materials, we still see that the "new" bar breaks at a logical weak point, the point at a bend and the end of a taper, while the "repaired" bar breaks further down at the repair point. This design was never going to break along the straight and uniform section otherwise. There are only two possible types of conclusions that are even possible at this stage of experimenting: 1, that the repaired parts fail at their cut points instead of the original design's weakest point indicates a weakened repair, or, 2, that these results are inconclusive. To say 3, that the repair was stronger or even acceptable is, well, dishonest, and demonstrates that your claims, methods, stats, proofs of any kind are suspect to manipulation and fraud.
This has done nothing to convince me that carbon fiber is safe to repair. Your testing methods are flawed. Aluminum can be damaged and still be safe to use, while CF is a gamble. No thanks! I'm hard on equipment so ill trade a few grams of weight for reliability every day of the week.
Every time I see a band shirt during one of these videos, I think: this guy gets me, similar tastes in music and a love for two wheels! Happy belated St. Paddy's day, everyone!
BIG Thumbs up for the Type-O-Negative love. Life time fan of band and NY Hardcore in general.
Wow, there was no standardization in testing methodology between the commercial bar and the repaired ones. Y'all need to remake this with both a larger sample size (I'd personally like at least 3 of each) of each break type and repair job, as well as a consistent and repeatable testing apparatus throughout the entire test. Maybe also throw in a break caused by the test rig rather than artificial means, repairing it, then retesting it. I'm disappointed quite frankly.
While the video editing was not as pretty as Ryan, I actually enjoyed this being a cyclist whom also rides a motorcycle. I got my carbon bike frame repaired professionally and always wondered about this. Im also curious about how much weight a carbon repair would add?
If you’re worried about the weight of a carbon fiber repair leave that power bar at home, it’s no good for you anyway.
carbon fiber repairs weigh a negligible amount when done properly. Rob did not do proper repairs, nor does he use proper PPE.
I have so far stuck to steel (e.g. VSFahradmanufaktur) bicycles over Alu and Carbon over this misconception!
No more.
Let’s start a go fund me to bring back Ryan
Did someone just hacked F9 channel? 🤔
I really loved the evil dead reference 😂😂
I was curious for you to break a bar in the test rig then have it repaired and tested again, would be better test I saw
A thumbs up just for the Evil Dead/Army of Darkness reference.
He missed an opportunity to say he ran down to the local S-Mart to get that brand new handle bar. :)
I can't believe more people didn't catch this, I was cheering out loud
The biggest problem here? Carbon fiber handlebars almost never break towards the ends. They almost always break near the stem and it's really obvious that they're toast. This video is much more applicable to anything other than handlebars
It doesn't actually make sense to repair handlebars anyway as they're easily replaced, fairly cheap and if anything goes wrong the consequences can be quite nasty.
The reason they did the test with handlebars rather than something more relevant is that they're easily replaced, fairly cheap and shaped in a way that makes testing easy.
Have read some of the comments, and have a few thoughts.
TLDR; It's an interesting video that isn't entirely wrong in it's point, but it feels like the type of experiment where you came up with a conclusion, and then set out to do some tests to just confirm that conclusion regardless of the actual outcome of the tests, which is a very bad way of testing something. Plus the explanation feels a bit like it's just glossing over everything except a small point that may not actually be relevant or accurate.
For the readers;
To the general conclusion, I agree that having some basic knowledge of your kit is good, even if you aren't going to work on it. Knowing you don't need blinker fluid is a good thing.
To the specific conclusion, I think it depends on the type of break and the event that caused it. If you broke your bars like that by full speed clipping a rock wall, that's probably fixable. If your carbon frame took a tumble and cracked the head tube, maybe not. Definitely have someone who knows composites inspect it though. Carbon fiber is certainly repairable, but only sometimes, not particularly easily, and often at the cost of weight and bulk, which is the strength of CF in the first place. Hence the conclusion, "it's [probably] not worth repairing"
To the methodology, there are definitely some issues with the process and sample size, but I also see some other issues. One big issue is the force measurement in the first place. The independent variable is the drop height, plus the mass of the weights if you had to change them after maxing out the height. Having the force is a useful data point, but it's not the factor being changed. Also, where is the accelerometer located? If it's in the center of the base or the bars, you would likely read a lower peak impulse at the breaking point due to the weights being detached from the bar before they have a chance to fully transfer their inertia into it and rebound back up. I'm a bit surprised that the first two bars didn't experience this, though possibly the height spacing was such that the peak force would have been between the two pegs? (This is based of my intuition with similar testing scenarios, please chime in if you have more experience with that type of setup)
Additionally, with the extra set of bars you seem to be talking about them failing due to fatigue and at a lower force than the repaired bars and a lower force than their peak, but regardless, that only really shows that the third set was not as strong as the two originally were. (Plus maybe the impulse measurement issue above) I assume the point of the last test was supposed to be to see if the repaired bars failed at a higher force than the unrepaired bars would have failed at, but using a different bar makes that kind of meaningless. It also doesn't make much sense given that if the virgin side of the bar didn't break at that height, a full bar likely wouldn't have either. The weights were also different between the first two sets and the last one, which confounds the result even more. (Also as someone with way too many 3D printed things, a shim for a set of barbell/dumbbell was probably a better idea from the start)
It also feels like the whole chart section doesn't make a lot of sense? What do the hollow circles represent? There were only a few tests shown, definitely not that many. Were those bounces? Were there more tests than were shown? Also, the peak vs break forces aren't labeled. Why is the second-to-last force measurement highlighted at all? Why are we just now learning that there was a "fancy" vs "quick and dirty" method? Which was which? What is the X axis? Also, why is there an X axis? Actually, why is this a scatter plot at all?
This definitely feels very out of place for F9. Having the whole video be "you should do a thing and it will often be as strong or stronger" _does test and determines that thing is not as strong_ "as you can see, you should do the thing" just doesn't make any sense.
Also as a clarification for all the people just saying "bring Ryan back", I do like the cycling content, and if it adds to the content instead of replacing the existing moto content in the schedule, neat. (Though I do think there is enough of a gap between motorcycles and bicycles I get why some of the audience doesn't like it as much)
This specific video and methodology just feels well below the standard for the channel.
I'm a bit embarrassed by my fellow riders who are complaining about MTB content on Fortnine
Now I don't pedal bike at all, but I still watch and enjoy these videos. I don't ride ADV either, but I still enjoy their videos when it's focused on that.
It's a free content channel, that is affiliated with a beautiful Canadian company, that also sells MTB products. They also sell snowmobile gear, and I would not complain for a minute if their channel included some snowmobile content.
If the topic of a single video is not to your liking, simply do not watch it, and wait for the next video that peaks your interest. There is no need for the disrespect.
First of all - thank you for the video! Please read this one carefully. The breaking test itself is not good at all. The main difference in these type of composite material is the possible persistence of micro cracks during operation and their accumulation in time. It's really not obvious that if you would test a new element with the same maximum condition you did (without any other breaking tests) - it would always broke, the element could survive extreme condition at first. You did a few tests with lower weights before you use maximum weight. This can be the reason of accumulation of critical persistence of micro cracks that lead to the point where the construction is no longer good enough to resist the force you use. The same thing is with the repair! You can not be sure that your repair is goon enough till you check it at reasonable level. Ride safe! All the best!
Do I trust repaired carbon fiber? I don't even trust NEW carbon fiber! 😳
Steel is real, baby!
Rob repaired a frame for us and it has been perfect ever since. We had him sign it and leave it unpainted just because Rob is awesome.
I don't mind the bicycle stuff, or the new cast, but please, do the actual tests better. Switching weigth types and not using the same handlebar at the end. So his repair was stronger with a wide soft sand weight than an unknown knockoff was with a steel weight. That does not tell me much.
Integrity is so important for this channel.
Can we get a link to the sick track that was playing in the middle and then again at the end? Love that funky groove, team F9!
Also, I'm a pool player and I'm sticking with my woody. No carbon fiber shaft for me thanks. 😉
Wow! That was so cool, stylish and unique! Loved every aspect of that video! Love motorcycles, mtb and Vancouver, dudes! Thank you for your job.
But help me with understanding, please. How is that happen, that last new bar was dropped from higher, but experienced less N of force? On first bar weights were kind of not centered right. We saw some Truvativ bar in some parts! Show us some proper branded parts maby?
And the most important is - what results would a proper alloy Renthal have?
Overload failure & crack propogation, as what happened to these bars, are not the same as fatigue. And with the retail bar covered in tape, it was also changed test configuration. Overall your point is true that sometimes carbon fiber parts can be repaired to be as at least as good as original--functionally. But per data, the repair changed the geometry by adding extra material & load distribution on the area of repair, so the strength is going to be different with the same force vs a new tube.
Love the Type O Negative shirt. Interesting video too
Years ago I had a carbon road bike frame fixed by Robert's Composites. I rode and raced it for ages after and was confident it was stronger than new.
You needed to calculate the impact energy, impact force and impact torque. The gym weights would’ve acted like a point load so the torque on the repair would be greater as the second moment of inertia of the bigger masses you started with would’ve been imparting a simple sheer force through the repair and this is the strongest loading mode of a sleeve repair.
You probably need to look at the amount of bar flex that is happening as well and compare the strength of the sleeve with the carbon fibre. Some sort of NDT (ultrasonics or dye pen) to look for signs of fatigue failure (cracking) should’ve been done between tests with this sort of testing method.
If I were to do this, I would get a load cell and a chain block, clamped the bars onto the ground or something heavier than the breaking load, so based on the numbers you have in the chart about 800kg (4000N per side). I would then sling the bars with a load spreader to make it so you have vertical loads at the handle part of the bars. Could probably use grip to stop the slings from slipping … then you just read the load cell display as you wind on more load with the chain block until it fails. This way it’s one load event per test and it’s infinitely repeatable.
Rocking the Type O Negative shirt, good one. Great video too!!
Thank you for the Evil Dead reference
Honestly, I'm a gravel rider, not a mountainbike rider (and well past the who-cares-if-I-hurt-myself age) but what strikes me as unaddressed here is the cost of carbon fiber repair. One suspects items such as handlebars would be cheaper to just replace. A frame, however, might be a candidate for repair. Regardless, I'm not sure I'm the type who could ever fully trust repaired carbon fiber (i.e., steel is real!).
3:40 watching the progression of carbon fiber, reminds me of Dave Ronneberg, and building the boot, after growing up with my father, that built a long easy and a cozy MK 4.
N528DR and N785R
I think those are the ones.
He built a couple of “epoxy boxes”, to keep it warm… I still remember the smell
FortNine in America live from Detroit... Y'all had me with that first part.
I'm watching this days after breaking cheap chinese aluminium handlebar risers that i put on my enduro motorcycle.... yes. from now on i will be careful and learn about what i'm doing. D'oh! thanks for the videos guys, good job!
I think the third bar used in the test should've been the same model, otherwise you've only proven that Rob's repairs are weaker than the original part. This isn't to talk smack about Rob, it just makes sense. Carbon fiber's strength comes from the continuous fibers having a very high ultimate tensile strength. If you break a piece you've now broken those continuous fibers. On the repaired part it looked like rob was inserting a patch of carbon fiber tube inside of the bars or patching it around the outside, but ultimately it will be the glue/epoxy that's holding the parts together. Glue can be strong over a large surface area (probably where Rob's point comes in) but it flexes even less than carbon fibers, so as soon as it cracks it fails again. Because the test was an impact test instead of a slowly increasing load test, it caused the repaired parts to fail sooner than expected. This in turn doesn't make it the best use-case for a bicycle to use repaired carbon fiber pieces in place of fresh ones, if we assume that the fresh ones got to a point where they did break.
We repair CF stuff in the aircraft industry, but yes, it's an art more than a science, and usually needs a pretty well controlled environment, and a skilled repair person.
Not a carefully-enough controlled experiment to draw any conclusions that I'd be comfortable hanging my hat (or somebody's front teeth) on.That was a reasonably hokey rig, which did not very carefully control for torque on the bars (i.e., the distance the weights were away from the stem clamp) or where the weights were relative to the repair. Spreading the weights over a ~20 cm area, as they did for the repaired bars, is not an apples to apples comparison of the loose plates of weights (which rattled on the bars on impact) that were attached to the "store-bought" bar. These differences might have substantial effects on the magnitude and direction of forces (impact and rebound) at the highest loading point (i.e., when the rack hit bottom). Further, in some of the takes, the weights came almost disastrously close to the presenter's toes - which are directly below the weight on the left when he is pulling the pin. Safety shoes maybe?
Absolutely fine to repair most carbon parts if it's done correctly. Super common in aviation. And a simple thorough tap test is usually all that is used for NDT.
Something that i would like to point out is the repeated dropping will cause the break ontop of the larger force exerted each time.
To folks complaining about MTB content: motorbike-centered F9 videos are often relevant to cyclists, so chances are you can learn a thing or two from these cycling-centered videos too. Have you ever used or considered carbon fiber components? Then this video is useful to you even if you don't ever spin your feet in circles.
Yeah and as usual on RUclips, if it doesn't interest you, don't watch it x)
We're giving the creator feedback. Seems to me most of the regulars following aren't happy with the direction.
Out of the last 30 comments I read 24 of them were complaining about this type of content lmfao
Cool story. Make another channel and go watch it there. I don't need notifications about pedal bikes. They're off until this crap stops.
I don’t ride motorcycles or bikes - I just like learning about engines and watching cool riding footage. I agree that this content is less interesting to me. I agree that F9 can post whatever content they want. I agree it’s easy not to click on a video I don’t want…
But if I find myself no longer excited when I see that red dot next to a channel with a new video, I usually unsubscribe
I think the unspoken point here is make sure you can find someone who can competently repair carbon fiber in your area. If such a person is unavailable then either expect to have to ship and wait on repair jobs outside of your area or use something else that can be locally supported.
Why are you doing bicycle stuff? Where's the snappy dude who does murder cycle stuff ?
This was a really cool watch!
Keep up the awesome work y'all!
Ive had both. Prefer metal due to bendy bendy than snappy snappy... Also whats the repair cost to new carbon bar ratio?
If the repaired part broke at higher force... why in the first two tests pe handle bar broke ONLY on the repaired side?
Yeah, it doesn't make sense. If the repaired side was stronger as the results are trying to suggest, surely the non repaired side would have broken first in the initial tests.
The random new bar breaking at a lower force is irrelevant. Even the test on the new bar was using different weighting.
And the funny thing is, I never got the movie reference until someone else pointed it out and called me an idiot ! Great stuff ! Thanks.
The test is wrong. There is a methodology error.
At the beginning you say: carbon fiber breaks up without surface warning signals.
But later in the test what you did is to stress the same bar multiple times creating "under the surface" breaking points and making it weaker for the next try.
If you pick a brand new bar and you test directly 1,60 meter, probably it WON'T break up.
At the same time if you pick one of the repaired and you test immediately the limit, maybe you will also see that you can push that limit further. BUT in the case of the repaired bars, decisive is how it broke and of course how good it has been repaired.
However you have to pick ONE new bar and run ONE test. Then change the bar, make another test, and so on. So you have equal starting conditions. Otherwise is like you are using unrepaired items and then you wonder, they are weaker than the brand new ones.
this
From a motorcycle content in to a carbon fibre steering bar breaking? What happened to this channel lately?
Loved the intro
It is a fine and interesting video. There are carbon fiber stuffs on motorcycle, there is no need to be that hostile.
Always pleasing to the ear to hear a Canadian say "beauty" in his native environment.
Of course the mountain bike rider segments are going... Downhill...
Not a fan, that Rob guy rules though.
Back to NatGeo rivaling motorcycle mini-docs please and aaaaaaathankyou
love seeing that Type O shirt!
Back in the day when I raced Rob Mulder’s boards were THE custom race board … note his T-shirt; Sailworks is Canuck transplant Bruce Peterson’s race sails, used by pro racers worldwide.
As demonstrated, carbon can be repaired as strong (or stronger) than original. And I have had an aluminum stem fail “catastrophically “ without any signs or warning.. so carbon isn’t the only material that can fail in such a matter.
Thanks for the content!👍
A failure which may only prove lack of observatipn on your part.
Possibly Dan; although there were no cracks/stress risers/creaks/etc. Certainly made me more diligent in pre-ride checking components. Cheers
Aluminum failure is predicted by the amount of load cycles. A margin of safety factor is applied to the predicted failure predictions.That’s how aircraft are engineered. Inspection of aluminum is relatively easy. Pre flight checks don’t just apply to aircraft.
Music choice is great. Genuinely got emotional during the repair segment.
Wouldn't adding that piece on the inside of one side change the balance?
And what was the piece made or? Was it carbon fiber, or metal?
Pity you didn't test a set of "safe" aluminium bars as well.
Btw , the new practice of adding an innegra layer to the carbon can substantially raise the failure point and the bars are less likely to shatter.
I'm gonna look that up, but what is an innegra layer? Interested because I've designed and built my own miniGP bike, did the body with fiberglass at first, then made molds, then redid them in carbon. Those aren't structural, but I've been thinking about getting more into the carbon work for my shop.
My Answer Pro-Taper carbon bars and they are indestructible mounted on a MTB. To be honest they are a little scuffed after 15 years with at least 10,000 miles per year on the dirt on rocks. Western Quebec/ Eastern Ontario riding.
I make speed dust sometimes too. But my speed dust related product floats. Been working with glass, carbon and Kevlar last 2 years. Its quite amazing what can be done. In reality carbon fiber is fiberglass but not. If you understand the grains and weave structure the strength will follow. Boat guys will tell you anything can be fixed. Whether you should depends on cost vs worth
What is supposed to be on the axis in the plot near the end of the video? I don't get what it's supposed to mean
Carbon fibre’s sharp broken edges are lethal and the dust particles are extremely toxic. I worked on a military base that stored damaged carbon fibre fighter aircraft parts. Strict handling measures were enforced. As for weight reduction, using carbon fibre on a bicycle is like making a feather lighter, the gains are incremental and frankly not worth the effort. It has its uses but it strikes me as what chrome in the 1950’s was, an ornamental selling point for the average consumer.
im starting to wonder if there has been a movie reference in every video, and ive just been missing them until recently.
Where’s Ryan? This has been a motorcycle review channel for so long.
One thing that wasn't mentioned, was the fact that a handlebar has a set outside size that can not be exceeded, or be unable to fit levers. That makes it a lot harder to make a stronger repair than original. In the case of the chainstay, you could likely increase the outside diameter with wraps of carbon under a vacuum for curing, as well as install a section inside, and that would be much stronger. I would never trust a handlebar, but seatstays or chainstays, yeah.
I, for one, am digging the variety on the channel. And carbon fiber isn't just MTBs! It's good info.
I never would have thought repaired carbon fiber would be just as good as original. I shoot archery, and most of my arrows are made out of carbon fiber. It's a great material because it doesn't bend and is light (unlike aluminum) and it takes a lot more stress to break than wood. (It's only downside is it can be expensive.) But when it does break, it's thought it's best just to cut off the broken part and shorten the arrow. But, maybe these arrows can actually be repaired.