I'm bummed to hear the bearings are not the same. I was planning to do a bearing swap this winter. Still can't find a high quality replacement for the F6901's. Did you?
How much of a gap are we talking about? .5mm on each side or a full 1mm or more per side? Filling the gap with some sort of spacer may be the best solution. I would be hesitant to modify the carbon.
Me too, I thought people up-thread had used these bearings already without issue, but it seems the F6902 2RS and the F6902 LLU have slightly different flange thickness.
I would say there is about 1-1.5mm gap total (both sides). My current plan is to get some thicker washers (2.5mm) to replace the washers that sit between the rocker and the frame. Unfortunately they are not a standard size, the standard washer with 15mm inner diameter is 28mm outer diameter, which is too big.
I haven't ordered the F6901 bearings yet, but I did find some online shops in Europe that stocked them.