I wonder if anyone here can help me figure out this Sram/GXP/BB30 crank compatibility puzzle:
I have a Stages non-drive power meter crankarm that I bought for an older mountain bike I have. The bike has a Sram S-1000 GXP crankset, with a pressfit (89mm) bottom bracket. The non-drive spindle diameter seems to be 30mm, and according to Sram’s website, the spindle interface compatibility is:
I don’t ride this bike much anymore and would like to swap the Stages crankarm to my CX/gravel bike, which gets more use. It’s not a simple matter of just swapping over the old MTB’s full crankset because the chainring sizing is too small; I like a 50/34 on the CX bike.
Can I buy a BB30 road crank and the appropriate bottom bracket and use the Stages non-drive crankarm with it? I suspect the q-factor might be a little wacky but I think I could live with that aspect.
I’ve tried to figure this out through various manufacturers’ websites, as well as searches on forums like this one, but I can’t prove to myself this (or any other combination) will work.
Any help from the collective wisdom here would be greatly appreciated.
GXP spindles are steel 24mm stepping down to 22mm on the non drive side. BB30 as the name implies is 30mm and aluminum and also much narrower as the bb bearings fit inside the 68mm wide bb shell whereas the GXP fits a standard English bb where the bearings are mounted into cups that thread into the frame placing the bearings outboard of the shell. A GXP crankarm cannot be interchanged with one from a BB30 crank. Also a BB30 crank will not work in an English BB frame but a GXP crank can be used in a BB30 frame with adapters. Hopefully I have not confused you but it is actually fairly straightforward.
Just to confuse you even more, SRAM (and others) make other 30mm cranks that have longer spindles to use on frames with wider BB shells. Some are labelled the same as the normal BB30 and you have to measure to find out which you have, some are labelled BB30+ or some other variation.
AFAIK, SRAM only used one NDS crank spline for each diameter of spindle, so your PM should fit any SRAM 30mm crank. Also bear in mind that their current cranks use a 29mm spindle so measure accurately!
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