These hybrid ceramic bearing kits from HSC are designed to fit Trek's BB90 road and BB95 mountain direct-fit bottom bracket shells, and are available for either Shimano Hollowtech II or Sram GXP cranksets. HSC hybrid ceramic bottom brackets are ideal for those looking for a noticeable upgrade from OEM bottom bracket options. With more and more cyclists desiring better performance from their bikes, HSC has heard their demands and has responded with one of the smoothest bearing sets we've ever felt.
HSC's ceramic hybrids use grade 3 silicon nitride (Si3N4) balls matched with hardened steel races and low-friction seals and retainers. The grade of the ball bearings refers to their sphericity in thousandths of an inch. Put simply, the lower the number, the closer the ball is to being perfectly spherical. As a reference, the highest quality stainless steel ball used in bicycle applications is rated at grade 25, and many ceramic hybrid manufacturers use grade 5 ceramic balls. Advantages over standard steel bearings include: lighter weight, lower thermal expansion and deformation under load, lower friction with reduced start and running torques, and reduced wear for longer running life. Again, put simply, ceramic bearings allow you to roll faster with reduced effort over a longer period before needing replacement.
We highly recommend all HSC ceramic bottom brackets be installed by an experienced professional using a proper bearing press when necessary. Often, though, BB90 tolerances allow bearings to be pressed in by hand.