Chainring
drivetrain
A chainring is the toothed ring at the front of the drivetrain that the chain runs over, attached to the crank. Bikes have one (1x), two (2x), or rarely three (3x) chainrings.
Common chainring specs:
- Tooth count (e.g. 50/34, 52/36, 53/39 for road compact / semi-compact / standard)
- Bolt circle diameter (BCD) — determines what cranks they fit
- Spider design — affects stiffness and weight
- Narrow-wide profile — alternating wide/narrow teeth, used on most modern 1x chainrings to retain the chain
Chainrings wear over time as the chain wears. Worn chainrings show "shark fin" tooth profiles. Replace them when shifting performance degrades or you can see significant tooth wear.
See also: Cassette.
