I have an í08 Cervelo Soloist Team with the so-so FSA Gossamer cranks and MegaExo bottom bracket. Because of the poor reputation of the MegaExo b/b, after 1500 miles I decided to change it out with a Shimano Ultegra FC 6601. I installed the new b/b last night and found the Gossamer crank spindle to be a very tight fit in the new b/b, so much so that I had to use a rubber mallet to get the spindle through both cups. The MegaExo spindle pulled out and went back in fairly easy. Is that because the original cups were worn, and the new b/bís tolerance is very tight? Everything Iíve heard says that the FSA cranks and Shimano b/b are compatible, right? Could my forcing the spindle with the mallet cause any problems/damage to the cups? I rode today (37 miles) and it seems fine. All answers/opinions appreciated.
2008 Generic Carbon Frame with full Ultegra, 2007 Iron Horse Victory 3, 2007 Fuji Absolute LX, 2005 Leader LD735 with Ultegra kit
not sure if this helps but i have cranks and BBs in both types, ie FSA gossamer in megaexo, and ultegra crank in ultegra BB. I never swapped them like you did, but the FSA crank was looser in the mega exo compared to the ultegra crank in the ultegra BB.
btw, i loved the shifting in the ultegra crankset alot more than the FSA gossamer.