Is it possible to repair a carbon bottom bracket shell (Trek Madone frame) that has been damaged by a broken press-fit bearing?
Yes, it is possible. The first thing to do is to build a cylindrical sleeve on a lathe with a diameter slightly smaller than the outer ring of the bearing. For example, in the case of a bearing with a nominal outer diameter of 42 mm, the diameter of our sleeve must be 41.900 mm.
The sleeve, suitably treated with release agents (to prevent carbon from sticking to it permanently), is then coated with carbon fiber. Next, after degreasing and treating the worn bottom bracket shell to promote bonding, we insert our carbon fiber-coated sleeve.
Everything is then mounted on the template to ensure the correct alignment of the sleeve with respect to the frame; once this is done, we move on to the composite hardening phase, placing the frame in the oven at the appropriate temperature.
At the end of the curing phase (composite catalysis), the sleeve is removed, the reconstructed surfaces are checked to ensure they are perfect, and the part is painted if necessary.
These are, obviously in summary form, the steps necessary to reconstruct the carbon fiber housing of the bottom bracket bearings.