With the SLR Crossmax MTB wheelset, what is the difference between the lefty, the center-lock and the 6 bolt?

Answer 1

Well.... the Lefty is a propietary fork that Cannondale uses on some of their bikes. It only has one stanchion, that's why it's called Lefty.

The other two options you mentioned are the type of disc brakes your going to use.

6-bolt is the standard rotor, and all brands offer them.

Centerlock is a sort of new standard from Shimano for their disc rotors. You could also find Shimano rotors in the 6 bolt configuration. But it's not that easy to put standard (6 bolt) rotors on a centerlock hub (some companies makes adapters).

Unless your going to build your bike with Shimano, buy the 6 bolt option.