|Dimensions - d (inside diameter)||19.05mm|
|Dimensions - D (outside diameter)||37mm|
|Dimensions - B (width)||9mm|
Original Enduro single row ball sealed bike bearing 21.5mm inside x 31mm outside x 7mm width
Grade 10 Chromium Steel Balls:
High precision balls are within 10/1,000,000″ round, twice as round as the industry standard, at it's highest level.
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-3 precision and noiseless movement.
Riveted Steel Retainer for toughness, ABEC-3 tolerances and noise tested, C-3 or C-N Internal Clearance.
The letters after the bearing number designate the type of seals that are used in the bearing.
“LLB” is a double-lip type seal making light contact, and also rides in a groove making a labrinth
seal. “2RS” literally means “Two Rubber Seals”
Bearing Code: MR 21531
Dimensions: 21.5 x 31 x 7mm
Grease: Mobile HP 222
Application: Hubs, Bottom Brackets