[guerrero101]

Hello all,

I need advice. I have a Specialized Stumpy Expert carbon with stock crank arms (XT) and BB91 bottom bracket. I also have a Raceface Next carbon crank arm that i want to swap with the bike, but want to know if they are compatible with BB91?
Any help would be appreciated.

 

[frdfandc]

Yes. BB91 is basically a standard BB system (external style BB cups) that have the bearings/cups molded directly into the frame of the bike.

As long as the spindle lengths are the same between the XT and the RF cranks (which they should be) it will fit no problem.

 

[guerrero101]

Frdfandc,

Thanks for your help but looks like i might need and adapter or new BB. The splines on the spindle wont allow to tighten up the crank against the BB. Im calling Raceface monday for a solution.

 

[frdfandc]

I found that you will have to have the BB replaced.

You will need this. Its a press fit BB for the BB91 system.

http://raceface.com/components/bottom-brackets/bottom-brackets/bb92-x-type-press-fit-adapter/