Bike Jargon Buster... Bike Components

All good bikes will have aluminium alloy wheel rims - they are lighter, don't rust, and the brakes (excluding disc or drum brakes) work much more efficiently than with chrome steel rims.

A mark of quality. Stainless steel spokes are not really any lighter than the cheaper galvanised ones, but they do look better and don't rust.

Like double-butted tubing, these are thinner in the middle where the extra metal is not needed. They are lighter, and funnily enough they are actually stronger than the normal ones (called "straight gauge").

Refers to how the wheels fasten into the frame and forks. A quick release wheel can be removed from the bike without using a spanner, since the axles are replacesd with shorter hollow ones, though which a lever is passed. This lever operates a cam tightener which clamps the wheel into position. Being able to remove your wheels without a sanner means you can more easily repair punctures or put your bike in the boot of your car etc. Without quick realease, you would need a spanner to tighten and untighten the wheel nuts.

Quick Release wheels are generally a sign of better quality but it is not always a good thing to have! If your wheels can be taken out by hand, then they are at risk of theft whenever you leave your bike unattended. You need to ensure that you lock your wheels as well as the bike!

The other, potentially more dangerous problem with quick release wheels is that they must be tightened correctly. Too loose and the lever can open on it's own allowing the wheel to come out. The forks on a bicycle now have to have "safety lips" or "lawyers lips" to prevent the wheel from disengaging if the QR comes undone.

If you plan to ride almost entirely off-road then a big knobbly tyre is perfectly suitable. BUT if like most people, you will be mainly riding on tracks and tarmac, go for a tyre which has a more solid centre tread. It will smooth out the ride and mean you are not wasting your energy.

If you plan to ride almost excusively on tarmac, a narrower smoother tyre will be easier to ride. If the bike you are looking at comes fitted with big knobbly tyres, ask the shop if they would swap them for some more suitable ones.

Some tyres have built in puncture resistance. These can be a brilliant addition but beware that NO tyre (except a solid tyre) is "puncture proof".

With the exception of expensive "tubeless" tyres, all pneumatic bicycle tyres require an inner tube, most commonly made of butyl rubber.

The key thing to look for is the type of valve used. There are three different valve types common in the UK;

Auto valve - sometimes referred to as "Schraeder" is like the valves on a car's wheels. These are the most common valve type. Under the cap, the valve is located inside the shaft and can be released by pressing the central pin. A special tool is needed to remove the valve. The valve shaft is 8mm in diameter.

Presta valve - sometimes referred to as "High Pressure" or "Sclaverand" is a high pressure valve capable of the holding the high pressures needed in racing bike tyres. The valve shaft is a narrower diameter (6mm) and the valve is typically lighter than Auto or Dunlop/Woods valves. The valve is released by undoing a small thumblock nut and pressing the release pin. Once inflated, the valve should be locked by tightening the lthumblock nut again. Presta valves are available in different lengths to suit many of the modern deeper bicycle rims. Presta valves should not be fitted to a rim which is drilled for Auto or Traditional valves as this may result in the valve being ripped out of the tube.

Woods valve - sometimes referred to as "Dunlop" or "Traditional" is a multi-part valve. More difficult to use than Auto or Presta since fitting the tube requires that the valve be removed and refitted one the valve shaft has been inserted through the rim. Wordlwide, the Woods valve is still the most common, although in the UK it has all but disappeared in favour of the Auto valve.

Puncture Prevention Treatments - can be inserted into your inner tubes and some bikes may even come fitted with "self healing" inner tubes from new. These treatments work on many pierced hole puctures but are not effective against all types of pucture.

Derailleur gears work by having several cogs at the front and back of different sizes, and use a cage mechanism (the derailleur) to "derail" the chain from one cog to another. It sounds unsophisticated and it is, but it is light and works surprisingly well. Derailleur systems are exposed to the elements so need a reasonable amount of maintenance. They can have 5, 6, 7, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21, 24, 27 or even 30 gear combinations, although there is quite a bit of overlap in the ratios.
Typically, a derailleur system consists of 1, 2 or 3 cogs (chainrings) at the front mated to 5, 6, 7, 8, 9 or 10 cogs (sprockets) at the back.

Hub gears have a gearbox built in to the rear hub, sealed away from the elements. Gears are engaged and disengaged by a pushrod from the end of the hub. Hub gears are heavier than derailleurs, but need a lot less maintenance, and are more forgiving of misuse. They can have 3, 4, 5, 7, 8 or 14 ratios, with no overlap between them.

Gear shifters are the controls on the handlebars which you use to change gear. Nowadays, almost all of them are indexed - this means that when they are correctly adjusted they "click" into gear and you don't have to guess how far to move them.

They come in three basic types:

Thumbshifters - These are simple levers sitting on top of the handlebars - push them one way to go up a gear, push the other way to go down.

Pushbutton shifters - ("STI", "Eazifire") These use (ussually) two buttons or levers, usually one for your thumb and one for your index finger. One button/lever will make the gear easier and the other makes the gear harder.
On road race bikes, the gear change levers are often built into the brake levers as are some top end mountain bike gear shifters.

Twist shifters - ("Gripshift", "Revoshift") With these, you twist a section of the handlebar grip to change gear. Twist shifters are almost always used with hub gear systems and are common on derailleur systems too.

These are brakes which work by squeezing the wheel rim.

There are two main types:

Linear Pull ("V-brakes" [tm]) or Cantilever - These have two arms fitted to the frame or fork, pulled together by a cable strung between them. V-types have long arms and one cable which pulls across the top of the tyre. Cantilevers have shorter arms and a Y-shaped cable which pulls upwards. Both types are very powerful, and are found on mountain bikes and many others. Cantilevers have all but disappeared now in favour of the more powerful Linear pull brakes, but they are still commonly used on Cyclo-Cross bikes.

Caliper - These are like pincers - pulling the cable makes them clamp onto the rim. They are not as powerful as V-type or Cantilever, but the new "Dual Pivot" ones come very close. Calliper brakes are mainly found on racing bikes.

All rim brakes have the advantage of being light, but can have problems in poor conditions - because the rim gets very close to the road it can get clogged up with mud or water, making the brakes less powerful.

Alloy rims combined with rim brakes will wear gradually over time. Most people expect to have to replace their brake blocks periodically, but don't realise that the rim wears too. The wear will be accelerated if you do a lot of riding in offroad conditions where grit and dirt are likely to get caught in the brake blocks. Even on the road, alloy rims can wear and you should be aware of this fact and keep an eye out to ensure you have your rims replaced before they break!

These work at the hub, not the rim, and fall into two types:

Disc brakes - These have an exposed steel disc at the hub, which is clamped by a small calliper. Discs can be very powerful, and are also pretty light. They are exposed to the elements, but because they are further from the road they are less affected by mud and water. Discs are popular on mountain bikes because they are so powerful. Economy systems are activated by a cable attached to the brake lever(s) whereas more expensive systems are operated using hydraulic fluid in a sealed system. See below.

Drum brakes (a.k.a Hub brakes) - These have a sealed drum at the hub, with two expanding brake shoes inside it. They are not quite as powerful as discs, but are completely sealed against the elements. They are heavier than other types of brake, and are often used on city bikes because of their very low maintenance.

Most brakes are operated by pulling a steel cable, but hydraulic brakes work more like that of a car, using pistons to compress oil which then transmits the force. Hydraulics have lower maintenance than cables as they are sealed - cables can get gummed up with mud or rust. They are also very powerful, as they multiply the force of your hand. They are typically more efficient than cable operated brakes because there is considerably less friction in the closed hydraulic system between the lever and caliper compared to a cable operated system. Hydraulics are available to operate on the rim (like cantilevers) or as disc brakes. Hydraulics are more expensive than cable-operated brakes, and require expert treatment if they go wrong.