I have carbon rims and race XCO and MTB 100s. If you’re going to lose weight anywhere, the wheels are the best place to do that, expecially since all the reaccelerating in mountain biking. Aside from the obvious weight savings, assuming there are some, below are the other benifits:
-
A major benefit to running carbon rims is their inability to flat spot like aluminum rims do. Over a large sharp impact, aluminum rims have the tendency to flat spot creating unequal spoke tension throughout the wheel.
-
When undamaged, carbon rims will always return to their round shape. Meaning, that when built properly, the spoke tension should not change. This translates to less time spent trueing and re-tensioning spokes through the season or after some big drops or crashes. I’ve rode on my carbon rims for a year, had several crashes and countless washouts and they are as true as the day I got them.
-
Even though all rims can be designed and manufactured very differently, carbon mountain bike rims have the potential to be very strong and stiff while remaining lightweight. This characteristic is much harder to achieve when using aluminum rims. Using a stiffer carbon rim gives you the ability to corner harder and with more confidence, and to accelerate faster out of the turns.