Ceramic Ball Bearings
Ceramic ball bearings are lighter, harder, and stiffer than common steel ball bearings. Since they are harder, they deform less while under load, meaning less rolling resistance. Some ceramic ball bearings have a roundness as low as grade 3, or round to 3/1,000,000 of an inch. Hardness rating is on the Rockwell C scale. The higher the number, the harder the bearing. Ceramic bearings have a Rockwell C of up to 75; harder than steel, which has a Rockwell C of about 60. Ceramic bearings can be in loose ball or cartridge form. ABI industries Enduro bearings are a good example of high quality ceramic cartridge bearings.
A cartridge bearing contains bearing balls, and two races for the balls to roll on. One race is on the inside, and the other on the outside. Seals prevent contamination of the high quality cartridge bearings. Known for their attention to detail and high quality, Phil Wood bearings are some of the best stainless steel cartridge bearings on the market. Phil Wood claims to have brought sealed cartridge bearings to the bicycle industry. Phil Wood has cartridge bearings available up to ABEC-10 with industrial grade marine seals to ensure long life.
Loose Ball Stainless Steel Bearings
three chrome balls image by Igor Negovelov from
Fotolia.com
Bearing systems of this type include two races and loose, stainless steel ball bearings. One race is in the hub, while the other is on a cone that threads onto the hub axle. This cone holds the balls against the inner race. Loose ball bearings for bicycle hubs of high quality must meet certain criteria. They must have a roundness grade lower than 25 or 25/1,000,000 of an inch, and a hardness of about Rockwell C 60. The ABEC rating only applies to cartridge systems. Cyclists know Shimano for high quality stainless steel loose ball bearing systems.
