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Cervélo bikes use a bottom bracket standard known as BBRight. I recently bought a Cervélo with a Shimano crankset, but I'd like to use a Quarq BB30 crankset.
I read that BB30 was compatible with BBright, but didn't do my homework properly. The Shimano spindle is 24 mm in diameter, while BB30 cranksets are 30 mm.
Can the BBright bottom bracket be changed to one that'll accommodate my Quarq power meter crankset?
As you found in your research, BBRight is based off of the BB30 standard, differing only in the placement of the bearings relative to the centerline of the frame. Shimano has never really supported BB30 or any of the related BB standards, instead steadfastly maintaining compatibility with their own Hollowtech II (24mm) standard. This means that any frame manufacturer wishing to use a full genuine Shimano drivetrain, including crankset, has had to either continue to build frames with the Hollowtech II shell specs or to include adapters from whatever standard they chose. In Cervelo's case, they elected to continue to use a BBRight shell (which is not coincidentally their proprietary standard) and develop an in-house bottom bracket that acts as its own de-facto 30-24mm adapter.
So what does this mean for you? It means that you can run the crank you want if you replace the bottom bracket with an original BBRight one, which is pretty cheap to do. A cursory google appears to indicate to me that these now carry the designation BBRight 30x90 to differentiate them from the Shimano-compatible 24x90 version. Other, non-Cervelo BB30 bottom brackets also may include the necessary spacers to work with BBRight (again, the only difference between the two is the bearing locations), but you'd have to do your research before ordering to be sure.
