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The language of bicycle parts

People who talk about bikes can sometimes sound like they’re speaking a language all of their own. Some of the words they keep using are completely unfathomable and bizarre, and some sound familiar but often mean something completely different than expected. The language of bikes isn’t just a way of keeping in the clique though – it’s vital to be able to identify specific parts.

The language of bicycle parts

Disc brake callipers

Disc brake callipers : (aka disc brake units) These are bolted to mounts on your frame and fork. Pulling the brake lever at the handlebar clamps the disc rotor between thin, metalbacked brake pads. Powerful and resilient, they can seem daunting to service thanks to the hydraulic system but they´re actually very straightforward. Mechanical versions use cables and V-brake levers rather than an oil-filled hose.

Cassette and freehub

Cassette and freehub : Your cassette consists of a set of different-sized sprockets bolted together. Currently nine-speed cassettes are most common and combine with the three chainrings on your chainset to give you 27 gears. Smaller cassette sprockets give you a higher (harder) gear for maximum speed, and larger sprockets give you a lower (easier) gear for climbing hills. The cassette is fitted to a freehub on your rear wheel.

Rear derailleur

Rear derailleur : This moves the chain step by step across the cassette sprockets. Differentsized sprockets give you different gear ratios, so that you can pedal at a constant rate over a range of different speeds. The movement of the rear derailleur is controlled by a cable on the shifter on the right-hand side of the handlebar. Correct adjustment gives you slick shifting and ensures maximum life for your chain, chainset and cassette.


Chain : The chain connects your chainset to your cassette, turning the rear wheel to provide drive when you pedal. It needs to be strong so it doesn´t snap when you stamp on the pedals but it also needs to be flexible enough to shift from side to side across the cassette sprockets and chainrings. Your chain´s width needs to match your cassette: for example, nine-speed sprockets are narrower and more closely spaced than eight speed, so you need a narrower nine-speed chain.


Chainset : This consists of two or three chainrings bolted together. Like the cassette sprockets, choosing a different-sized chainring gives you a different gear ratio. Larger chainrings give you a higher gear that is harder to push but propels you further on each pedal stroke. Smaller chainrings give you a lower gear, allowing you to climb steep hills. Chainrings will wear out over time, the teeth being worn away or hooked until the chain starts to slip and suck under pressure.


Headset : The main bearing at the front of your bike, the headset connects your forks to your frame. This part is often ignored because it’s mostly hidden in the frame. This bearing must be adjusted so it turns smoothly without – any play or binding will affect your bike’s handling. There are two types of headset: the threadless, or Aheadset, which is found on the vast majority of bikes, and the old-fashioned threaded headset. Regular servicing of the bearings keeps them running smoothly and last longer.

Cables and hoses

Cables and hoses : Connecting brake levers to callipers or V-brake units, these need to be kept in good condition to transmit an accurate signal. Speed control, as well as raw braking power, is vital. Steel cables run through lengths of outer casing from brake levers to V-brakes. Hoses are the stiff plastic tubes that transfer hydraulic brake fluid from hydraulic brake levers to callipers.

Bottom bracket

Bottom bracket : Bottom brackets are another ‘out of sight, out of mind’ component. The bottom bracket axle connects your two cranks together through the frame. If worn and loose, the bottom bracket can lead to front gear-shifting problems and cause your chain to wear out. Worn bottom brackets can be spotted by checking for side to side play in your cranks. Usually supplied as a sealed unit, this part must be replaced when worn or stiff. This repair needs a couple of specific but inexpensive tools.


Wheels : Building wheels can seem daunting, but it is very satisfying to ride around on a pair you have built yourself. Building a wheel consists of two steps: weaving the spokes together to connect hub and rim, and tensioning each spoke so that the rim is flat and perfectly round. A wheel jig is essential for this task. It holds the wheel steady and has indicators that help you decide which spokes need to be adjusted and by how much.


Suspension : Suspension makes your ride smoother. Almost all new mountain bikes come with front suspension forks and full suspension bikes (with a rear shock unit as well) are available in a wide variety of flavours, from 4” short travel XC bikes to 10” downhill machines. Suspension forks absorb trail shock, making your ride more comfortable and increasing your control. They let you go faster than you would on a rigid bike, and they need setting up for your weight.


Hubs : There are two types of hub bearing : cup and cone, and sealed cartridge. Sealed cartridge bearings are a sealed unit that includes the bearing race as well as the balls and are designed to be used until they wear out, when they should be replaced. Cup and cone systems can be serviced and should get an occasional clean and re-grease to keep them running smoothly.


Pedals : Introduced from road bikes, clipless pedals have replaced clips and straps. The cleats, small metal parts that are bolted to the bottom of your shoes, clip into a sprung platform on the pedals. They are initially daunting and everyone falls off when they’re learning to use them, but once you´re used to the release mechanism, you´ll appreciate the additional security. Alternatively, you may choose to use flat pedals; these usually have sharp pins to grip the soles of your shoes.