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Glossary

Ever been bamboozled by a bike shop, so you don’t know what you’re paying for?
Here’s my handy guide to the most common terms and parts.

Drivetrain

Cassette: The set of toothed sprockets on the back wheel, responsible for changing your main gears.
Chainset: The set of toothed sprockets, turned by the pedals. The term usually includes the ‘cranks’.
Cranks: The arms on the left and right side of the bike, with pedals at each end. Often the right hand crank is bolted to the chainset.
Drivetrain: The chain, cassette and chainset together.


Wheels

Front hub: The central axle on the front wheel, on which the wheel turns. It can become loose and the parts inside can wear.
Rear hub: As above, but on the back. The hub will have a unit on the right hand side onto which fits your cassette.
Spokes: The thin metal bars running from the hub to the wheel. They are supposed to be tight, and may not be laced in the same way on both sides of the wheel. Loose or broken spokes will buckle your wheel.
Trueing: The act of tightening and loosening spokes so your wheel runs ‘true’ – that means your wheel runs straight, as a perfect circle, and is not biased to one side (dished). It can be a bit of an art to get it right!
Nipple: The bit at the rim end of the spoke that you tighten or loosen with a ‘spoke key’.
Rim: The big circle into which the hub and spokes are tightened, creating a wheel.
Tyre: The ring of spongy, tread-marked material that sits on the rim. The numbers written on the side tell you the size of the wheel. These are useful numbers to know.
Tube: Or inner tube. The rubber sealed tube, with a valve poking out of the rim.
Presta: A type of tube valve that is thin and has a little unscrewable metal end on a pin. Mostly found on road bike tyres.
Schrader: A type of tube valve that is thicker, and is used in car wheels too. Mostly on hybrid and mountain bikes.

Gears and brakes

Brake lever: You squeeze them, and the bike comes to a stop.
Rear gear shifter: On the right hand side of the handlebars. Changes gear from easy to pedal (1) to harder (5 and upwards).
Front gear shifter: On the left hand side of the handlebars. Expect two or three gears. For example, Gear 1 is easiest to pedal and the chain sits on the smallest (‘granny’) ring at the front. Gear 3 is hardest to pedal, and is the outside ring.
Gear cable: Transfers your wishes to the gear mechanisms.
Rear derailleur (‘mech’): Backwards ‘S’ shaped mechanism that moves your chain around on the cassette sprockets at the back.
Hanger: Soft piece of metal that fixes your rear mech to your bike frame. If you damage this area, the soft metal bends, saving the more expensive mech. Lower end bikes often don’t use hangers, and mid-range derailleurs cost as much as a new hanger anyway.
Front derailleur (‘mech’): Does the same job on the front, but with fewer sprockets.
STIs / Integrated gear and brake system: Combines the braking and gear shifting controls on your handlebars into the same unit. Most road bikes have them.
V-brake: Strangely, it looks like an ‘H’ and pulls your brake pads together via two pivots on the frame, either side of your wheel.
Noodle: Curve of hollow metal that fits a cable into a V-brake, then through a squashy rubber thing, before the cable is secured to the other side.
Calliper break: Looks like a ‘C’ turned 45 degrees, secured to the bike with one bolt. The cable pulls on one side, closing the breaks on both ends of the C.
Disc break: Instead of brakes closing on the rim, a circular metal plate is attached to the centre of the wheel. Brakes mounted on the frame close on the plate. Most often on mountain bikes, but increasingly on road bikes.

More complicated

Headset: The column that comes up from the front wheel, with which you steer. There are lots of parts in there, and it takes a lot of abuse when riding.
Bottom bracket: The piece of kit which threads or pushes through the bottom of the bike frame where your pedals go round. Don’t mess, if you don’t have the right tools.
Bearing: Metal balls which reduce contact and therefore friction between moving parts. They come either as a bunch of loose balls, in a kind of cage, or in a nice sealed (but disposable and more expensive) ‘sealed bearing’. You’ll find bearings in bottom brackets, hubs and headsets.
Groupset: The combination of chain, cassette, chainset, cranks, bottom bracket, gear mechs, breaks and STIs, all under one brand name, such as Shimano Tiagra, or Campagnolo Super Record. To be honest, if you’re familiar with groupsets, you probably don’t need to be reading this glossary.

Corrections, qualifications and questions very welcome!