Drivetrain
Drivetrain
Everything that turns your legs into forward motion: cranks, chainring, chain, cassette, derailleur and shifter. A modern mountain bike runs one chainring and twelve sprockets — 1×12.
Also known as: 1x, 1x12, groupset, transmission
Key facts
- Standard
- 1×12, cassettes up to 10–52 T
- Speeds
- 12
- Service interval
- clean and lube the chain every few rides
The parts
- Cranks and chainring — where the pedals push.
- Chain — the part that wears fastest.
- Cassette — the sprockets on the rear wheel; the biggest is for the steepest climbs.
- Derailleur and shifter — move the chain across the cassette.
Why one chainring
Older bikes had two or three chainrings and a front derailleur. A single ring with a wide-range cassette — 10–52 teeth gives a range of 520 % — covers nearly the same gears with fewer parts, less weight, a chain that stays on over rough ground and one shifter to think about.
Choosing the chainring
A smaller chainring makes every gear easier: good for long climbs and tired legs. A bigger one gives more top speed. For most riders 30–32 teeth is the middle of the road.
Wear
A chain stretches as it wears and then wears out the cassette and ring too. Measure it with a chain checker and replace it in time — see chain care.
Related articles
- SRAM — An American component maker from Chicago, founded in 1987. It made the 1x mountain drivetrain mainstream and owns RockShox, Zipp and Quarq.
- Shimano — A Japanese maker of bicycle components founded in 1921 in Sakai. Its drivetrains and brakes are on more bikes than any other brand's.
- Cross-country (XC) — Mountain biking as an endurance sport: as much up as down, on light and efficient bikes, where fitness wins races. The only mountain-bike discipline at the Olympic Games.
- Chain care — A clean, lubed chain shifts better, runs quieter and saves the cassette and chainring. Clean and lube it every few rides and replace it before it wears out everything else.
- Technical climbing — Getting up steep, rooty or rocky climbs without putting a foot down. It takes the right gear before the hard part, weight over the front and smooth, patient pedalling.
- Boost — The hub-width standard of most modern mountain bikes: 110 × 15 mm at the front and 148 × 12 mm at the rear. Wider hubs make stiffer wheels and leave more room for tyres.