Chainrings23
Chainrings can last a long time but are a wear item in a bicycle's drivetrain. Keeping your chain clean can increase their lifespan.
Crankarms traditionally have a set of four or five arms which the chainrings bolt onto. The Bolt Circle Diameter, or B.C.D., it the size you need to know to find compatible chainrings. Common road, track, and touring sizes are 110mm and 130mm, common MTB sizes are 94mm and 74mm. If your cranks are Italian it could be anything, and some more modern cranks have asymmetrical patterns, or sometimes no arms: their chainrings are attached with a nut at the spindle.
- Double and triple chainrings allow the chain to move smoothly between them: the inner chainring is simple but the outer are ramped and pinned for indexed shifting. 11-speed and above needs compatible rings.
- Single chainrings can be in a narrow-wide pattern, to allow the chain to shift on the rear cogs without falling, or in a straight pattern. The latter can be for 1-1/8" track chains, or 3/32" geared chains.
- All chainrings are aluminium except where indicated.
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