Thursday, January 4, 2007

Bike Anatomy

The beauty of a bicycle is that it is such a simple device. Even so there is still plenty of jargon and technical sounding language to deal with. To save you from bafflement in the bike shop we've produced this quick guide to all the main parts of a bike. We've used a road bike but all the information here still applies to other bikes too.

BRAKE LEVERS Pull these to stop: part of an integrated STI lever (along with the gear shifter) on road bikes, on their own on Mtbs.

STI/ERGO SHIFT LEVERS Road bike gear changers that are integrated with the brake levers. There are two different systems: Shimano STI (shown) and Campagnolo Ergolevers.

HANDLEBARS There are a number of variations on two basic types: drops, for road bikes (as pictured) which give a choice of handholds, and flat bars which give a more upright position.

STEM Connects the handlebars to the fork. Stems come in a number of different lengths and angles. You can change your position on the bike by fitting a shorter or longer stem.

HEADSET SPACERS Only on A-head style headsets (see 7): round and washer shaped and fitted either above or below the stem to alter the stem height.

HEADSET This separates the fork from the frame, holding the fork in place and allowing you to steer; different systems are available: A-Head and Integrated being most the common.

HEAD TUBE Short front tube usually with the maker's badge on it. Contains the headset; and the fork passes through it.

TOP TUBE Connects the head tube to the seat tube- often called the cross bar. Mtbs and compact road bikes (as here) have sloping top tubes, standard road bikes have horizontal ones.

WATER BOTTLE Fits in a bottle cage which is attached to the bike via bottle bosses (threaded holes) on the down tube.

SADDLE Wider more padded saddles are good for slower riding, longer thinner saddles are best for distance and speed. Saddle choice is a very personal thing, though women buying a new bike should ask for a female specific saddle to be fitted.

SEAT COLLAR A round clamp at the top of the seat tube (see 34) which clamps the seat post (see 36) in place - can either be bolted or quick release.

REAR BRAKE Along with the front brake (see 32) there to stop you. Road bikes have calliper brakes, touring bikes and older Mtb have cantilevers, newer Mtbs more powerful V-brakes or discs.

CASSETTE (Or rear cogs) the spread of gears - 7, 8, 9, 10 - changed using the right hand shifter (see 2). Cassette cogs come in a variety of sizes for greater speed or climbing efficiency.

SPOKES Connect the wheel hubs to the wheel rims.

QUICK-RELEASE SKEWER Sprung loaded skewer with a handle at one end and a nut at the other which allows you to remove your wheels easily. Always do them up properly.

REAR DERAILLEUR (Or rear mech) shifts the chain between the cogs on the rear cassette (see 13)

REAR WHEEL Made up of spokes, hub and rim. The rear hub contains a freewheel which is connected to the cassette.

CHAIN STAYS Near horizontal tubes connecting the bottom bracket shell (see 22) to the seat stays (see 32) forming the rear triangle. The rear wheel fits into dropouts at the end of the stays.

CHAIN Connects the gears of the front chainrings with the rear cassette. Chains are specific for 8, 9 or 10 speed systems.

CHAINRINGS The front gears which are attached to the crank arm. Come in single, double or triple versions. Multiply number of chainrings by cogs on the rear cassette to give number of gears.

CRANK ARM Pedals at one end, chainrings at the other: available in different lengths to suit the length of your legs.

BOTTOM BRACKET Cartridge mounted axle that joins the cranks to the frame - your bike's drive unit.

PEDALS Can be either platform, toe clip and strap or clipless - your shoe attaches to the pedal via a cleat to give extremely efficient pedalling. Some bikes, especially more expensive ones, don't come with pedals so it's worth checking before you buy.

DOWN TUBE The diagonally angled tube from the headtube (see 7) to the bottom bracket (see 22).

TYRE There are two main sizes: 700C for road bikes and 26in for mountain bikes, there are lots of different widths available too. Fat tyres give a more comfortable ride, thinner is faster.

INNER TUBE VALVE Through which air is pumped into the inner tube/tyre. Two different types of valve are available: Presta (a thin needle shape), and Schrader (looks like a car tyre valve) - handy to know if buying a pump or new innertube.

FORK Holds the front wheel and connects (inside the headtube [see 7]) to the handlebars via the headset and stem. Usually made from steel, but aluminium and carbon fibre are also available. Suspension forks are common on mountain bikes.

FRONT BRAKE Various types available (see 12): use your front brake to slow you down first and your back brake to stop.

FRONT DERAILLEUR (Or front mech), this lifts the chain and moves it between chainrings (see 20) when you use the left hand STI lever or gear shifter (see 2).

SEAT TUBE The steeply sloped tube in the centre of the frame into which the seat post fits (see 31). The front mech (see 29) also fits onto the seat tube - at the bottom.

SEAT POST The post to which the saddle attaches. It's crucial to grease it occasionally to stop it seizing in the seat tube. You can raise and lower it to achieve correct saddle height.

SEAT STAYS The diagonal tubes on the frame which link the seat tube (see 30) to the chainstays (see 18). The rear brakes are attached near the top via bosses.

Source: Cycling Plus: Know Your Bike. website.

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