I've been building a new bike from a used MootoX YBB frame over the past few weeks. The XX1 group arrived so I started to install the components. The frame has a 68mm wide BB shell, so as instructed I installed the GPX BB with one 2.5mm spacer on each side. It turns out the 34t chainring I ordered is too large for the frame. It starts touching the seatstay before tightening the crank arm completely. The crank arms (168Q) have plenty of clearance.
Sram's specs for 32t rings show it as being 4mm smaller in radius. That should fit the frame without interference, so downsizing the ring is one option.
Out of curiousity, I shifted both spacers to the drive-side and reinstalled the crank. In this configuration, the 34t ring clears the chainstay with just over 1mm to spare. Enough clearance as far as I've read.
My question is this: what, if any, negative effects will mounting the BB 2.5mm to the right have? I'm concerned that the XX1 derailleur/cassette are so fine-tuned that the offset will cause chainline/shifting issues and extra wear. Or less likely, that the offset enough to affect my pedal stroke, e.g. cause knee pain?
I appreciate any input.
Mtbr's 2016 Winter Biking GearReviews and Roundups
Results 1 to 2 of 2