Blacked headset ABEC 3 angular contact ball bearing with 40 mm inner diameter, 52 mm outer diameter, 7 mm thickness and double-lip type sealing.
Enduro Bearings don't mess around with inexpensive headset bearings, it's simply not worth it. While many headset makers will offer you Cr-Mo or standard steel headsets for your carbon road bike, steel cross bike, or full suspension mountain bike, they feel that's like putting bias ply tires on a rally car. Enduro Bearings don't offer the entry level for headset bearings. Instead they begin with chromium steel, Black Oxide finish A/C type and then offer full 440C stainless steel at the top. They are always engineered with the largest balls possible and dual lip seals riding in a micro groove for ultimate protection against sweat and the elements. They are filled 90% with high pressure water proof grease, so you don't have to ever guess if there is grease inside.
Black Oxide bearings which get an additional Fe3O4 Iron Oxide (Magnetite) treatment are corrosion resistant close to stainless steel but have a better load capacity as this.
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.
ABEC 3 bearings use grade 10 Chromium Steel Balls and 52100 High Carbon Chromium Alloy Races.
The high precision balls are within 10/1.000.000″ round, twice as round as the industry standard, at it's highest level.
The alloy races are made from a 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-3 precision and noiseless movement. The riveted Steel Retainer stands for toughness, ABEC-3 tolerances and noise tested.
Manufacturer item code: ACB 4545 150 BO
Weight supplement: manufacturer spec