Bicycle Mechanics - Carbon wheel warning ...
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I was visited by my old LBS owner from Haarlem. He rode up le Mont Ventoux earlier in the week, and when he started down - the steepest bit, toward Bedoin - his rear wheel melted. That is the best way to describe it, I guess. It is an LEW all carbon wheel that he uses for time trials, etc., but it swelled and started to come apart, as he was hard on the brakes (if you have seen that stretch, and the traffic there, you understand why all the braking).
May be old news, or wrong use, but perhaps worth posting.
Well haven't seen that yet, but would be interesting to see if my LBS has since we live in a desert with mountains surrounding us that bikers go to and the heat can exceed 100 degrees. Many of the LBS's around here are now reporting problems with Carbon Forks not lasting long. The one mechanic friend of mine rides about 10,000 miles a year and after just 3 years of use he has to replace his carbon fork twice. He says carbon has the shortest life span of all bike materials. Be interesting to see what others think.
05-31-03, 04:40 AM
LEW are ultra-light racing wheels, best left to competition day.
Which bit of carbon melts?
I understand (did not see it) that the brake pad area expanded so much that it essentially froze the brakes open. He had to open the brakes (Shimano) to remove the wheel. Nothing actually parted company with the wheel, it just deformed radically.
05-31-03, 04:50 PM
Carbon rims should use a special pad just for them. It has, I think, a lower friction rating to keep the wheel from heating up so fast as carbon braking surfaces are pretty grippy.
Carbon should be pretty durable. It is the only material used to build bike parts that has, for all intents, an infinite fatigue cycle. There might be issues with joining it to other materials but that would be an epoxy issue not the fault of the carbon.
Carbon is another way of describing composites. If you go to various aircraft sites you will find that most composites have a temperature limit. The one exception is for composites which have been set at high temperature, using an appropriate epoxy, and whaich are baked in an oven to ensure a good high temperature cure. It is not very likely that bicycle components have been baked. Therefore a high temperature could cause delamination. I think you could follow links from www.eaa.org or go to the soaring society of america website.
Hw was using the proper pads for carbon braking surfaces.
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