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Chainset guide

Chainset guide

The chainset defines your bike's gearing

Every bike has a chainset. It is the name given to a group of components that rotate when you turn your pedals, to drive the bike's chain and turn the rear wheel to propel the bike along.

The chainset has two sides. On the right is the drive side, which is a crank arm attached to one or more chainrings. On the left is the non-drive side, which is just a crank arm. In between is a spindle which passes through the bottom bracket in the frame, which is simply a set of bearings on which the cranks rotate.

chainset exploded

Where to start?


If you want to upgrade your chainset, it's crucial you make sure it's compatible with the rest of your components.

Firstly, there are many different types of bottom bracket, including square taper and Shimano Octalink on mountain bikes, and press-fit and external bearing on road bikes. Chainsets often come with the right bottom bracket included, but in that case you need to make sure the bottom bracket is compatible with your frame.

Secondly, you need to make sure your chainset is compatible with the rest of your drivetrain - the chain, rear cassette and front and rear derailleurs.

If you are in any doubt about the compatibility of a new chainset, call 01792 799508 or email info@tredz.co.uk for advice.


Change your range

The size of the chainrings determine your bike's gearing. Larger chainrings give harder, or bigger, gears.

Bikes have one, two, or three chainrings, depending on whether they have a single, double, or triple chainset.

Chainset types

Compact, double or triple?

The type of chainset you choose will depend on the range of gears you need. There are four main types.

Singlespeed chainsets These have just one chainring. They are often used on hub geared bikes or singlespeed bikes, which have just one gear sprocket on the rear wheel. Some bikes, particularly mountain bikes, have a cassette on the rear wheel with several gears and a singlespeed chainset.

Double chainset As you'd expect, double chainsets have two chainrings. Depending on the number of sprockets on the bike's cassette, this means the bike will have 14, 16, 18, 20, or 22 gears.

Triple chainset This is a chainset with three chainrings. Depending on the number of sprockets on the bike's cassette, this means the bike will have 21, 24, 27, 30 gears.

To change your chainset from double to triple or vice versa, bear in mind that you will probably also need to change your shifters, front mech, rear mech and bottom bracket. If you need more advice on what compatible parts you need, contact info@tredz.co.uk.

Chainset types

Mountain bike chainsets

Off-road gearing

Choose the right chainset for your riding style and the terrain.

Triple chainset Three chainrings give mountain bikes the wide range of gears they need for climbing and descending. There is some overlap in gearing between the chainrings, so in reality a bike with 27 gears will have rather less distinct gear ratios. This is why double and single-ring chainset set-ups are now becoming more popular, as they can now offer a similarly wide gear range, but with less weight.

Double and bash This is the same as a triple chainset, except the largest outer ring has been replaced by a bashguard. This protects the remaining two chainrings. This set-up is suited to aggressive riding where the chainset needs protection.

Single ring and chain device This increasingly popular set-up has just the one chainring with a cassette and rear derailleur at the rear of the bike. A chain device is often used to help guide the chain and stop it coming off the chainring during gear changes.

Road chainsets

Gearing for speed

Get the best option for speed or versatility.

Road double A standard road double is usually found on more serious racing bikes, as it is has high gear ratios for flat-out speeds. This does mean steep uphills are more challenging, as it lacks the low gears to make pedalling easier. A road double is most suited to road racing, fast descending and time trialling.

Compact chainsets A compact chainset is also a double-ring chainset, but it has smaller chainrings to make pedalling easier on hills. It is perfect for sportive riding, general road riding and commuting.

Road triple Some road bikes have a triple-ring set-up to give a similarly wide range of gears to that found on a standard mountain bike. This is useful for riders needing a wider range of gearing, for instance touring or hilly sportives.