MTB Sprockets

What is an MTB sprocket and what is its main purpose?

The sprocket (chainring) transfers power from the crank to the chain. Unlike shifting chainrings, singlespeed rings for Dirt Jump have taller teeth to guide the chain securely even on rough rides, eliminating the need for a chain guide.

What mounting standards exist?

Direct Mount (SRAM 3-Bolt)

The ring is screwed directly onto the inside of the crank arm with three Torx bolts. This saves weight and looks very clean. A widely used standard.

104 BCD (Bolt Circle Diameter)

The classic 4-arm standard. The ring is attached to a spider with four chainring bolts. Very robust and common on older or budget cranks.

Cinch (Race Face)

Another Direct Mount system used specifically on Race Face cranks.

Which gear ratio do I need?

The choice of tooth count depends on your rear hub cog. A typical Dirt Jump gear ratio is around 2.6 to 2.8.

What materials are used?

7075-T6 Aluminum

The gold standard. Extremely hard, aircraft-grade aluminum that is CNC-machined. It is light and wear-resistant.

Steel

Cheaper and more durable, but significantly heavier. Found more on entry-level bikes.

How do I install a chainring?

• For Direct Mount: Remove the crank arm from the axle, loosen the 3 bolts on the back, swap the ring, secure bolts with Loctite.
• For 104 BCD: Loosen the 4 chainring bolts using a 5mm Allen key and a peg spanner. Tighten the bolts in a cross pattern.

What do the specifications mean?