We have a Co-Motion speedster and the front BB is starting to pop and creak. I've replaced the bearing cartridges at least once before, maybe twice, over the 8000 miles ridden. Wondering if it's worth it to invest in a Chris King BB? Also it appears the the front BB is 68mm and the rear 73mm, can anyone confirm this? Lastly, is it a good idea to have the frame refaced before installing the rear external bearing cartridges? I don't think this is possible on the front because the elliptical BB that the bearing cartridges thread into is already machined flat.

Thanks for opinions and insights.

Doug

You are correct that the Mega Exo BB was made to fit a 73mm rear shell but our Speedster had 68mm shell and uses a spacer to take up the slack. The BB was made to work with a 73mm Santana as well as a Commotion.

Our bearings lasted about 6,000 miles. We sold the bike at about 11,000. Bearing life has quite a few factors. BB shell facing if it is off could be killing your bearings since external BBs, rely on the shell being faced correctly. That being said I think Comotion usually does a good job on that. If you have a shop that can do it I would consider it. Some have gone to ceramic bearings to extend the life. Might be a good idea if you ride on wet roads a lot. Personally I think external BBs bearings might be a little on the small side if you want long life. Small bearings are lighter however. Big bearings are heavy.

I am interested to see what others with more miles on a Comotion say.

Ceramic bearings in the winter? These need servicing every 40hrs. according to Sram.