BSA is another way of stating English threading; it comes from British Standard Cycle. English threading on road bikes mean a 68mm wide, 34mm inside diameter shell with reverse threading on the drive side. It’s the most common threaded standard employed today.Put more of your energy into forward motion by reducing frictional drag wherever you can. CS Standard Bearings typically have frictional drag of 0.3-0.4 watts per set. That’s in the range of a 75% drag reduction compared to standard bottom brackets. CS balls are 100% smoother and 15% harder than ceramic competition. The bearings last at least 3x longer than other bearings. Spindle Compatibility: 24mm, 30mm, Dub[28.99mm] About CeramicSpeedRight from the beginning, when ceramic bearings were used to break the 24hr inline skating record, CeramicSpeed has had a focus on winning. Using tech developed for NASA, ceramic bearings are created and used in components for you to go faster more efficiently.