Chainrings

Measure the bolt circle diameter on your existing crank and count the bolts. Current Shimano 11 and 12-speed road cranks are 110 BCD with four bolts, older road cranks are often 130 BCD with five, and SRAM road uses 107 BCD on some models. BCD is not interchangeable, so a 130 BCD ring will not mount on a 110 BCD crank regardless of tooth count.

Oval rings smooth the dead spot at the top of the pedal stroke and load the downstroke more, which some riders find helps on sustained climbs. The evidence is mixed and the response is individual, so treat it as a preference rather than a guaranteed gain. Look for rings that allow clocking adjustment so you can tune them to your stroke.

Usually not on the same drivetrain. A 12-speed chain is narrower, and the tooth profile and ramp design of a ring are cut for a specific chain width and shifting system. Mixing them tends to produce poor shifting under load and accelerated wear. Match the ring to your drivetrain speed, which is listed on each product page alongside the BCD and mounting standard.

The offset sets the chainline, meaning how far the ring sits from the frame centreline. Many direct-mount MTB rings come in more than one offset, and the correct one depends on your frame's rear hub spacing, typically Boost or non-Boost. The wrong offset will shift poorly at the extremes of the cassette and wear the chain faster. Check your frame standard before ordering.

Often yes, particularly when moving between a double and a single ring, because the required bolt length changes. Reusing worn or wrong-length bolts is a common cause of creaking and of rings working loose. Steel bolt kits are the durable, inexpensive choice, and alloy bolts should always be fitted to the manufacturer's torque figure with a torque wrench.