TREK-SPECIFIC (BB90/BB95) GXP CHRO STEEL ANGULAR CONTACT

THE BALLS are made from chromium steel. These high precision Grade 5 balls are 5/1,000,000” from exactly round in sphericity. For comparison, Shimano and Campagnolo use grade 25 balls in their top-level components. When talking ball grade, the smaller the number, the "rounder" the ball.
THE RACES ARE A PATENT-PENDING ANGULAR CONTACT DESIGN, vacuum de-gassed 52100 high carbon chromium alloy steel, hardened to Rockwell C-62.
THE RETAINERS are nylon with Graphite and are virtually frictionless.
THE SEALS are "LLB" low contact labyrinth type, with 2 sealing lips which fit into a matching groove on the inner race. The outer sealing lip repels dirt and water while the inner sealing lip retains the grease. When the bearing is first turned, you will notice some grease will come out of the seals. This fills the chamber between these 2 sealing lips, forming a “hydromatic seal.” Seal material is NBR rubber.
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Bottom Bracket Bearing Kits