When decending on tubs, for example an alpine or pyrenean mountain can delamination occur on tubular carbon rims?
Also am i right in thinking the only drawbacks of a carbon tubular rim are:
1) braking may become grabby when the rim becomes too hot
2)the heat may melt/soften the tubular glue
3) lack of braking power if decending in rain
I know this depends on your weight, decending ability and wheel brand, but in principle am i correct. The wheels in question are campy hyperon 2 tub.
@gb103, tubular wheels have been used in professional racing in the mountains for many years now. They have been proven appropriate for those conditions.
I suspect that the carbon clincher didn't just 'delaminate', rather, it looks like it was blown apart by an over-heated clincher. That is the problem with carbon clinchers. Tubulars do not have that problem. The glue does not overheat. The tubulars do not burst due to overheating.
With respect to being 'grabby', that is a problem of carbon wheels generally. Cork pads help with that problem a bit (for good weather, though). You can also get Kevlar braking surfaces on ADA wheels, which are better, too.
eric wrote:[...]Surprising to see foam core construction in $6000 wheels.
For all those who wonder about "cheap" foam in expensive composite parts => http://en.wikipedia.org/wiki/Sandwich-structured_composite
Concerning the pictures: keep in mind that the wheel was damaged during riding, so it is very hard to evaluate just with the help of a picture what caused the accident and what was caused by the accident!
The shown wheel was out of production 08/2010. Every wheel comes with clearly visible stickers that tell you to carefully read the manual. Appropriate warnings were posted beginning with the first clincher manual!
btw.: nice to see this issue here in the forum, for sure only to warn people of the danger caused by carbon clinchers!
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gravlax wrote:For clarification, in regards to the posting by Carbonsports GmbH. while descending in heavy rain, the wheel delaminated and inner tube exploded. By luck, and the fact I was not going that fast, I was able to come to a complete standstill without the bike ever touching the ground. Therefore no chance the accident caused any damage seen on pics. Based on conversations with friends in the bike industry in Britain, Germany and France, I believe this type of delamination is not that uncommon with the particular type of Lightweight clinchers I rode. Let's hope the My 2013's do not have the same issue. Just to be extra safe however, this summer in the Dolomitis I am riding on alloy wheels.
Riding alloy wheels during long descents, wet or dry is a very good idea. In fact I want alloys during any mountain riding. I just don't see any significant advantage of carbon given the robust construction and relative light weight alloy clinchers available today (eg; Shimano DA C24's). Yes, carbon wheels may carry a few grams less weight but they also carry risks - not the least of which is relative poor braking.
I don't believe any carbon wheel is immune to possible delamination due to the intense spot heating effect and resulting shear forces generated within the composite structure (including any core material like foam). Cores of foam or honeycomb do add structural integrity however, these cores are generally bonded to the laminate and this junction itself is subject to shear forces during heating (see the article posted by Carbonsports above).
It would be nice if Carbonsports provided information on the testing that they subject their wheels to in order for customers to better educated and able to make the decision whether the risks of carbon wheels are worth the staggeringly high price.
A friend of mine who lives in Germany was on holiday with me and he immediately put the wheel in his car, promising to send them to CarbonSports when he got home.
I have just heard that the verdict of CarbonSports is that the wheel is not repairable and they have offered me 30% off a new wheel. Is this reasonable? It's not my fault that the braking surface is faulty. I know it's out of warranty, but should I spend a huge amount of money (even with discount) buying a wheel which is prone to this kind of fault?
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