Richard has a good point about aluminum crank failure. Aluminum has no lower fatigue limit. When you have applied XYZ stress cycles of force PDQ, and F(XYZ, PDQ) > max, the crank WILL fail. Steel has a lower fatigue limit - if you can keep your stress cycles below this limit, a 531 steel frameset will last forever.
In other words, in 100 years we may still be riding our cambio corsa bikes, but by that time all the nuovo record bikes will be TOAST.
- Don Gillies
San Diego CA