There seems to be an assumption that the bearings in the BSA30 adaptor are tiny, but I'm not sure why they would be. The bearings do not fit inside the BB shell and so the extra spindle diameter is besides the point. The bearings are in external cups and are sited outside the threaded BB shell, so in theory they could be as big as anything, assuming clearance from the crank arm.



I run the BSA30 in my Cervelo P3 with a Quarq Riken/S975 in BB30. No problems, but take care to space it out evenly DS>NDS to maintain the correct chainline. The only problem I ever had was with positioning the cadence magnet when I received the Riken spider under warranty, it was a bit tricky. But you don't need a magnet with your P2M.

Question - why not get a native BSA power2max, do you just really like the Rotor cranks? This "stiffness" bit with BB30 is a load of old cobblers I reckon. You push the pedals, the crank turns the chain. One of the only genuine advantages I ever saw was that a "proper" BB30 crankset can have a narrower stance width or Q-factor, but that doesn't work for everyone. Besides which, the Rotor BB30 has the same Q-factor as a BSA chainset anyway. I'd just get the FSA one if I were you, unless you have a pressing need to swap it quickly into another BB30 bike without using adaptors on that one.

Cheers,
Rich.