Kogel offers podium-grade ceramic bearings only in all of their bottom brackets and, although some riders are skeptical, the result is smooth-rolling bearings on your bike. This is the case for Kogel Bearings' BSA Bottom Bracket, which is the classic English thread for mountain bikes, and is also known for its durability and simplicity. The frame shell width is typically 73mm with a 1. 37-inch by 24tpi thread, and the BSA Bottom Bracket takes advantage of all of the benefits of its ceramic bearings. Kogel creates their bearings with a silicone nitride that combines a set of material properties with the result being a hard, flawlessly round ball with a smooth, low-friction polished finish. We like that ceramic bearings don't rust or oxidize, so they can last if properly taken care of.