71903-LLB ABEC5 Enduro Angular Contact Bike Bearing 17x30x7
Angular Contact (A/C) cartridge bearings are specifically designed for hubs. In standard radial bearings, only 3 or 4 balls make contact during the load, at any given time. In Angular Contact (A/C) bearings, ALL balls are engaged and spread the force over a larger surface area, to decrease friction, and minimize wear. Wheel play can be adjusted out of the hub, to giving a more stable wheel, making it easier to adjust disc brakes, while still spinning freely.
When fitting these angular contact bearings ensure the load is applied to the inner ring on the red seal side of the bearing.
Enduro ABEC-5 Specification:
Grade 5 Chromium Steel Balls
High precision balls are within 5/1,000,000″ round. These are military level specification, used for precision equipment. R-64 hardness, of the highest grade.
52100 High Carbon Chromium Alloy Races
Vacuum de-gassed process for the purest chromium alloy steel, hardened to R-62, extremely tough and very durable. Polished to a mirror finish for ABEC-5 precision and noiseless movement.
Graphite/Nylon Ball Retainers
Nylon with graphite retainers are virtually frictionless while providing constant lubrication.
The ABEC-5 Standard
To meet the ABEC-5 standard, bearing design must pass all tests, which include noise testing at high RPM, extremely close tolerances for I.D. and O.D., roundness of ball, trueness of the races and micro surface finishes of balls and races.