Stem Top Caps
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- Опубликовано: 13 сен 2024
- This video looks at some of the differnt stem top caps available, including weights for the weightweenies!
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Playback speed x1.25 is perfect
At first I was convinced the silver plate on your scale was the top tap, and was trying to figure out why specialized used such a small bolt size for their top cap..
I always learn something my Brother. You and Hambini are my favorites.
Meanwhile, I just have a steel frame and a quill stem... (with a healthy smear of grease!)
I remember reading somewhere the original aheadset design came with a plastic top cap designed to break if you over-tightened it and put too much preload on the bearings.
People kept breaking them so companies started selling aftermarket aluminium ones...
I still have one of the original plastic ones.
You should see that CyclingTips weight weenie build where the guy removed the top cap after preloading the compression plug!
I thought the first cap/total pic, was my grandmother's 1960s aluminium saucepan lid. Great info and congrats on 16k subs. The super cut out cap probably off a mtb with alloy steerer.
Thanks, even on an aluminum steerer it's not ideal!
@@LuescherTeknik I wouldn't use even on my mtb either it's just silly.
When I saw the 1st & 2nd I thought why does he say it's carbon, looks aluminium to me, they both look the same? I was looking at the aluminium scale as the cap and the black top cap as the handle.
I never thought top caps could be .....Fascinating. How about rear mech hangers??
I sweat a lot so I put grease everywhere I can including the top cap and under every spacer to maximize water repultion.
Actually I am more interested in the bottom side of top caps. If these are not flat (and most are not), you will have to push the compression plug further down in order to get the preload onto the bearings. This could cause the upper clamping of the stem to have no compression plug resistance and cause steerer tube damage. Even with an extra spacer below the top cap the upper clamping of the stem could still miss the compression plug.
I have a top cap with integrated Gopro mount. It's extreme in that aspect. It goes so far down that if I would want to have it flush with the stem, I'd have to cut my steerer at least a centimeter below the top of the stem. That seemed like a bad idea to me, so now I have a spacer on top of the stem instead.
A square piece of electrical tape over the top cap bolt, inside and out, is essential to keep sweat etc from creeping into your compression plug.
With respect to the Specialized "wagon wheel" star shaped cap, i only ever saw it on mountain bikes. 99% of them had aluminum steerers and were open through the bottom. However, their S-Works xc mountain bikes often had one piece carbon steerers and still had the same top cap. There were problems associated with that, though not what one would think.
I have seen quite a few road bikes with this cap fitted #weightweenies
Spank has a nice O-ring seal on it. Star shaped graphics if youbwant to look for it.
Wherever the top cap provides compression, does the stem have to be placed in exactly the same position?
Just wondered, got a new Trek where I've lowered stem but top cap is still at the top. To get them aligned I'd have to cut down the tube
Countersunk bolts are lighter and more aero than cap head ones.
Also it is easy to stick a bit of PVC tape over the top of them to keep the sweat/water out
Thank. I did not expect any problems from the top capr ...
Just a quick note on the specialized cap. It is only used by spez on mountainbikes with alu steerers and steel starnuts. Water goes straight through. No problems with that.
Yes there are problems, the steel rusts and the 7075 steerer is susceptible to stress corrosion. Especially that dirty water, mud etc can be acidic or alkaline.
Luescher Teknik But steerers on suspension forks are already open from the bottom and full of mud. The only issue with their setup is the three legged starnut they use. They break when people overtighten the compression bolt.
one of those cheap sweat guards is my bikes headset area saviour. keeps my sweat from falling right on there
The hollowed out topcap is generally used on MTBs where the steer tube is aluminum (with star nut) and the bottom of the steer tube is a hole that drops dirt above the front wheel. The alu/steel galvanic battery is much less severe than the alu/carbon one and you aren't trapping any dirt in the steer tube/fork because it just exits out the bottom. It is dangerous to use on carbon forks though.
Dirty/muddy water can be acidic or alkaline which can damage the 7075 aluminium steerer. Steel star nut rusts also. Less than ideal.
@@LuescherTeknik I'm curious how much worse/different a setup like this than any other disimilar metal interface (like a crank/axle interface or even regular bolts in an alu frame). I don't think it would be significantly different but I'm also not an expert.
The next video about compression plugs, please! 😎
He made one about two years ago. Very informative.
ruclips.net/video/8bSnbjHiFXc/видео.html
Sir ive been building my bmx for 1 year and 10 months now cause im poor and i dont have the money to buy original bmx parts but can you help me. Ive found a handle bar and a for with a stem on it so do you need a star knot for the stem to hold on to the fork or not..?
That star designed top cap was standard on many specialized MTBs.. Maybe someone think they can put in on road bikes too..
Just curious, what's your view on the current "UV Resistant Paint" that all the company are claiming today? I still observe discoloration on the frames over time.
- How much protection does these paint provides?
- Will this affect the resin?
- Whats the industry expectation for the longevity of these paint?
- Does this mean it is not wise to purchase those "naked" frames?
correct UV will eat into your frame but Ive never found it to be an issue. I had an SWorks Epic for 12 years and it was yellow looking. Never had an issue.
I use a Titanium top cap, ok alu is slightly lighter and carbon is more still, but Ti looks nice and a great metal 😉 ps I rode a carbon and they aren't worth it !!! 😒
Unrelated to this video, have you had any Ridley carbon frames in for cut up and analysis? Thank you
A lot of these weight weenie parts are made for hillclimb bikes where they might only get used for 10x 1-10 minute races per year. I don't think people care about the rain issue for that. (At least, here in the UK)
Does 3 grams really make a difference????
@@LuescherTeknik You should come to the UK and check out the hill climb season here. It's 1000% bonkers.
It's pointless, as in case of a top cap, you can just leave it off. Bond in an aluminium tube as steerer support where it's clamped by the stem, temporarily install an expander and top cap to compress the bearings, tighten the stem, take top cap and expander off. Put a sticker over the hole.
I get it, but the reality is that the tears you cry when it fails will weigh more 🤣
On the super cutout 5 spoke stem cap, I've only ever seen those on MTB, and it's just for looks cause you can see the tire through the pipe. I cant see any problem as debris just falls out and any sweat that gets in would be flushed out with any normal washing.
Yes there are problems, the steel rusts and the 7075 steerer is susceptible to stress corrosion. Especially that dirty water, mud etc can be acidic or alkaline.
@@LuescherTeknik thanks, those are good points
I see those star cutout caps on mountain bikes all too often. So much dirt in there!
Yes it's not ideal.
On my mountain bike I have a big 35mm hole ready to eat dirt. I don't see how this could cause more dirt?
Raoul, any thoughts on magnesium stems that were so popular about 15 years ago, mainly around the corrosion issues?
Unless they had a durable coating, corrosion would be their downfall.
I just weigh my 10 month old 13g carbon stem cap/bolt and I feel dirty for it. Corrosion under the bolt, underside has flaking, mostly dry outdoor rides, one Winter.
Meanwhile, my 12+yrs all weather 17g Specialized alloy top cap/bolt still doing it’s job.
Raoul is there a structural advantage to making wheels and frames with foam cores?
@@samhe1521 Oh, that makes a lot of sense. Why didn't I think of that...
What do you think of the old Canyon without a top cap but just a ring around the top.
Less than ideal.
@@LuescherTeknik But.. but.. aren't Germans "genious" engineers?
Does one top cap fit all?
Canyon's early top caps were non-existent... since they used an ACROS conical spacer that did the compression plug duties. Literally no top cap shipped with those bikes. "Genious German engineering"... #amiright ?
In the real world too light = short life. Also get some decent legs & man up. Train on a training bike, race on a race bike. All the gear no idea VIRUS everywhere
Hi Raoul, what your take on Easton internal threading set up. autobus.cyclingnews.com/photos/2008/tech/shows/interbike08/index.php?id=/photos/2008/tech/shows/interbike08/interbike0813/Easton_steerer
I used this system once on one of my cyclocross bikes and well don't know from structure of safety standpoint but was easiest and most consistent system I've ever used outside of star nut in an alloy steerer.