I have an extra set of 3D cranks and would like to put on my mountain bike. Going to order the 104/64 spider.

I have a few questions before I order the spider.

1. Are the spindle lengths the same on road and MTB versions? My MTB BB is 73 and road is 68? I'd hate to find out that the spindle is too short during installation. Quick search online I didn't find anything specifying different spindle lengths with the 3D.

2. In the instructions there are spacers that are required where they are not needed on the road versions. Does the MTB spider dish so much that it will require those spacers?

http://www.rotorbikeusa.com/pdf/3d_manual_8-18-10.pdf

I'm going to use a Raceface 30T single ring and use the Shimano 24mm BB thats in the frame.

I posted here because well...not too many people visit the MTB section.

Any help would be appreciated!

Thanks!!

The spindle on the 3d+ mountain crank is a lot longer than the road variant. The arms are also different, they splay out more. It is definitely able to accommodate a 73mm shell, as well as wide set chainstays.

Thanks for the reply!

I have the 3D non "plus" version...so I can assume its the same way?

Just look at the Q-factor difference between the road/MTB versions of Rotor cranks - it's significant.

Q156 XX/XX1 and XTR Race cranks both have issues fitting many MTB's and you'd like a use a crank that's considerably narrower than either of those?

Not saying it is impossible, but it sounds like you haven't thought this through very well and at the very least need to take a few measurements...