Can BSA 68/73 bottom bracket be used in place of fat bike BSA 100 mm I have a fat bike with SRAM GXP 100 mm bottom bracket. Except for the length of the plastic sleeve that connects two cups, it looks exactly like BSA 68/73 mm bottom brackets used on non-fat MTBs. I wonder if it is possible to use BSA 68/73 cups with this fat bike. The original longer plastic sleeve can be reused if necessary, because it barely gets any wear during exploitation.

This would greatly extend number of bottom bracket options compatible with my frame.
The spacing is the only difference across the SRAM/TRUVATIV GXP line of BB's, so yes, you can use the 68/73mm left/right cup set on your frame. Just reuse the center seal/spacer from your existing BB, especially if you're riding a lot in the winter or rain.

Funny enough I've seen cheaper prices for the less widely used 100mm than the far more common 68/73 so it might make sense to just buy the right width unless you've got a good BB source!