Angular contact bearings are a step forward in outboard bottom bracket design. Why? Deep groove radial ball bearing cartridges are not designed to be "adjusted." Any inward or outward pressure on the inner races put them out of alignment with the outer races, forcing the balls to ride up the side of the groove and exerting greater pressure on the races. This results in increased friction and premature wear. Since almost all outboad crank sets exert some inward pressure on the bearings when installed, it only makes sense to use a bearing designed specifically for such loads. Angular contact bearings also result in 100% ball engagement when pre-loaded, making them stronger and longer-wearing.
ENDURO ANGULAR CONTACT ABEC 5 440C STAINLESS STEEL BEARINGS
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. 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.”
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