Carbon fiber doesn't do very well under repeated vibration and shock loads, and is very susceptible to UV damage. This can of course be mitigated, but that's p

Carbon fiber doesn't do very well under repeated vibration and shock loads, and is very susceptible to UV damage. This can of course be mitigated, but that's part of why CF frames are expensive. And in the end, the weight savings are rather small, most people do fine on hills as long as they have the appropriate gearing.