What Does ABEC 5 Mean? ABEC 5 is a standard which requires each bearing to pass many tests in order to meet the scheduled requirements. This includes noise testing at high RPM, extremely tight tolerances for the internal diameter, outer diameter, roundness of ball, trueness of races, and surface finish of all of the above. This is a much higher standard than ABEC 3, even though only differing by 2 digits in rating.
THE BALLS are made from 440C stainless 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 ANGULAR CONTACT RACES are 440C stainless steel, with a small compromise in longevity compared to the 52100 alloy steel, but with a far greater resistance to corrosion.
THE RETAINERS are nylon with Graphite and are virtually frictionless while providing constant lubrication.
THE SEALS are "LLB" (light contact, dual-lipped labyrinth). The LLB sealing mechanism is a low contact labyrinth type, with 2 sealing lips which fit into a matching groove on the inner race.