Alex EvansĪ shorter crank arm tends to enable you to keep up a higher cadence. The crank length – ‘170’ – is visible on the back of the crank arm pictured here. Crank lengthsġ70mm cranks are common on mountain bikes. It is a lot simpler, though, on a single-ring setup, with only chain length needing much consideration. If you do want to swap chainring sizes, check for compatibility beforehand. Groupset brands also recommend a maximum difference in the number of chainring teeth that a front derailleur can deal with, so you can’t usually increase the jump between rings.Īlso, the teeth on a chainring are sized for the number of gears on your bike so you can’t, for example, use an 8-speed chainring with an 11-speed chain, because the teeth would be too wide in that instance. Swapping chainring sizes on a double or triple crankset isn’t as simple as it sounds, because specific chainrings are designed to work together, with tooth positioning and ramps on the rings there to help the chain shift smoothly.Ī mismatched pair of rings might make for particularly awkward shifts from the small to the large ring and there’s an increased risk of the chain falling off the rings altogether, whether you’re shifting up or down. Swapping chainring sizes is possible, but compatibility needs to be considered. There is a wide range of power meter models available – read our guide to the best power meters – but they are pricey and you may need specialist tools to fit them in place of your bike’s existing crankset. Pedal-based power meters are also popular. Power meters incorporated into the crankset’s arms or spider are popular with performance-focused road cyclists (and some mountain bikers and gravel riders, too). You can’t easily swap the number of chainrings your bike is set up for, because the front derailleur and associated shifter will be specific for your setup and would need to be replaced, too.

There are exceptions though, which we’ll come on to. The chainrings are usually bolted onto arms that protrude from the right-hand crank arm, also called a spider. However, chainring sizes vary significantly, with options for every type of riding, so we’ll cover them separately below.

Single-ring systems, known as 1x drivetrains, are becoming increasingly popular on gravel bikes and can be found fitted to road bikes, too.Ĭombined with the cassette, the number of teeth on the crankset’s chainrings will define your bike’s gearing. Modern systems will give you plenty of range both for getting up hills and faster riding. Two chainrings are most common on road bikes, while the latest mountain bikes tend to come with a single ring. Georgina Hinton / Our MediaĬranksets generally come with either one, two or three chainrings.

Bottom teeth numbers