Chainring Buying Guide

Selecting the right chainring for road, gravel or mountain bikes can cause confusion, but thankfully we've got plenty of solid advice so that you can choose the correct option for your bike.

If you have any questions about chainring size or your drivetrain in general, pop in and see our workshop team or contact us online.

What is a chainring?

Bike chainrings are the toothed discs attached to the crankset that engage with the bike chain to drive the rear wheel. They come in various sizes and configurations, affecting the bike's gearing and pedalling efficiency.

The chainring is a segment of the two-part system used to gear your bike, allowing you control over how much resistance you feel while pedalling, as well as how fast you are able to do. It consists of between one and three rings, with 2x (two-ring) chainrings being the most common.

Brands such as Absolute Black even offer oval chainrings, which are said to provide riders with more efficiency, while Q Rings from Rotor are also a popular alternative to standard chainrings.

Ratios explained

Every cassette (rear gear set) and chainring has a number of teeth on each ring. This will range between 10 and 36 (or more depending on bike style) on the cassette, and 30 and 55 on the chainring. This gives rise to the ratio of a specific gearing system, which is indicative of how many revolutions the rear wheel will do for each turn of the pedals. The ratio can be calculated by dividing the number of teeth on the chainring by those on the cassette.

Which chainring is right for me?

The bike chain ring you need depends on your bike type, chainset, and intended use for your bike.

Cranks will attach to your chainring with either a five-bolt or four-bolt component known as the spider. Newer bikes tend to be four-bolt, whereas the rest are five-bolt. It is important to note that you cannot attach a four-bolt to a five-bolt or vice-versa, so be sure to check the number of bolts on your current chainring before purchasing a new one.

Chainrings from Trusted Brands

At Sigma Sports you'll find suitable chainring sizes for road bikes and gravel bikes from the leading component brands such as SRAM, Shimano and many others. For those who prefer riding off-road on mountain bikes, then we have chainrings from brands such as Wolf Tooth Components built for top-speed use off the beaten track.

Chainsets to go with Chainrings

Some chainsets can handle larger or smaller rings than others. For example, 1x chainrings (having just a single chainring) are available from 38T (38 teeth) upwards, whereas compact 2x chainsets (having two chainrings) have a 34T inner ring and 50 tooth outer ring as part of the most common setup. However, changing your front chainring set-up is possible, so change it to something that your current chainset couldn’t handle.

Bike Use

One of the most important things to consider when changing chainrings is how you’re looking to use your bike. If you’re an avid road racer who spends most of their time on flat roads, smaller chainrings will not be particularly helpful to you, so you’ll seek larger chainring sizes. However, large chainrings aren’t as useful if you prefer to climb steep hills, and smaller rings will be welcome. Matching your chainring to your bike usage is vital.

How to replace a chainring

1. Remove the chainset
2. Loosen the bolts that keep the ring(s) in place and remove the ring(s)
3. Degrease the bolts and apply a fresh layer of grease.
4. Reassemble the chainset (either with your old or new rings) - there should be an alignment arrow or chain pip (small protrusion in the chainring) that will help you align it with the crank.

Front Chainring FAQs

Does a bigger chainring size make you go faster?

Yes, if you can generate the cadence to generate the speed, but it will make pedalling at slower speeds more difficult. Make sure you find a chainring where you can go at the speed you want while still accelerating and holding your desired speed without extraneous effort.

When should you replace your chainring?

There’s no exact number for this. It depends on how much you change gears, how often and how far you ride, the conditions you ride in and the condition of your chain. If everything is in order, chainrings can last a long time. However, a poorly maintained chain, with lots of mud and grime left on it, will significantly decrease your chainring and crankset lifespan.