I bought a downhill frame (Commencal DH Supreme 2012) that I want to build up with parts myself. Now I'm trying to pick a suitable crankset for the 107mm bottom bracket. Having a hard time finding anything. It seems like not even the Saint group supports 107mm BBs. Where should I start searching? I'm not looking for specific advice but I need to find a place start or maybe I'm not getting it right with the specs.
According to the tech sheet at http://www.commencal-store.co.uk/PBSCProduct.asp?ItmID=12450127 you need a Press-fit BB.
PF107 should have 41mm diameter cups, have the same overall width as an External-bearing BB in an 83mm shell, and be compatible with the same cranks as "normal" external-83mm BBs.
SM-BB71 should work in your frame, and allow you to fit FC-M815 cranks. The cups will be the same as the "73mm" pressfit BBs, but the inner cover (aka spacer tube) is longer for "83mm".