The BB90 bottom bracket design foregoes the thread-in cups of the familiar external bearing bottom bracket. Instead, the 37 x 24 x 6mm ceramic bearings in this FSA bottom bracket assembly press directly into the 90mm wide x 37mm i.d. shell on the frame. The Trek Madone is the best known bike model using this system, though surely others exist.
This FSA kit includes the two ceramic cartridge bearings, one red anodized aluminum dust shield/spacer, and one wavy washer. Our FSA BB90 Ceramic Bearing Bottom Bracket Assembly is specifically designed to be used with their K-Force Light and SL-K Light carbon fiber crankarms. The dust shield goes on the drive side and the wavy washer should be installed between the left side bearing and crankarm. Note: this kit will NOT work with FSA's alloy cranksets. Actual weight is 42 grams.