Any ideas on what’s wrong with the outboard bearing designs on BB’s? From everything I read, they’re just not holding up, especially (but not limited to) the FSA designs. We’re running FSA Mega Exo carbon cranks with Mega Exo BB’s and I’ve already replaced the Captain’s BB, which failed miserably after about 2300 miles. The stoker’s BB is suspect now. Although the FSA cranks are fine, I’m thinking about going to Phil BB’s and Campy or Sugino square taper cranks this winter because the Phil’s seem to be bulletproof, albeit a step back in time. I would consider the Ultegra (not DA) Octalink design, but I don’t think they will be around much longer due to Shimano’s planned obsolescence programs.
Theories in various forums abound:
1. The BB shells must be perfectly parallel.
2. The bearings on the outboard designs are too small.
3. The cups are too flimsy for the loads imposed.
4. Lousy bearings and seals.
5. They can’t stand up to the sideloads imposed.
6. The integral crank/spindle is slightly off center and “orbits”.
Any thoughts? Who is able to reface tandem eccentrics and would it make any difference if I’m hostage to the other issues? I figure if I can put Phil’s on and be happy for 15,000 miles or more, by then they will have solved the issues with these “modern” designs.