Bike Jargon Buster... Bike Frame Materials
Bike manufacturers use a wide range of materials to make their frames, many of them very sophisticated. The aim is always to make the strongest, lightest frame possible for the money.
What bike frames are made out of:
Confusingly in the bike business, alloy means specifically aluminium alloy. An alloy (technically) is a metal with other things added to improve some of it's properties. Lots of mass-production bikes are now being made out of aluminium alloy. The manufacturers say they do it because it is light - it is, but not really any lighter than a good steel. One reason it is becoming very popular is that aluminium tubes are thicker than steel, so are easier for computer-controlled robots to weld. It doesn't rust, although road salt can make it go a bit funny. It is also nice and shiny! Aluminium can feel rather harsh to ride, though - it is very stiff, but the newer good alloys are addressing this problem. You should be aware that aluminium has a limited life - aluminium frames usually have a guarantee of five years maximum as they fatigue.
What bikes are traditionally made of. There are lots of different grades of steel used for making bikes, from solid-but-heavy exhaust-pipe tubing to really high tech alloys which are extremely light and strong. Steel is going out of favour because all but the cheapest stuff is too thin for robots to weld - highly-skilled humans are needed instead. Good steel frames can still cut it with the best though. Steel has a bit more of a spring in it than aluminium - the ride will be less harsh. Steel frames will rust, but if looked after can last a lifetime - steel does not fatigue like aluminium.
The dream material! It is lighter than almost anything else used for bike frames, very strong, does not rust, does not fatigue, and produces very responsive bike. So what's the catch? Titanium, while relatively cheap by itself, is very difficult to cut and weld, so titanium frames are expensive.
Also called a composite, this is a mixture of a matting of carbon threads and epoxy resin - like fibreglass but using carbon threads instead of glass. Carbon fibre is strong and light, and because the manufacturer can decide which direction the fibres go, the frame can be made stiff in one direction and springy in another. Because all these layers need to be bonded together properly though, it is expensive, and it can also be quite delicate.
This has been used for components and things like suspension forks for a while, and is now just starting to be used for frames. It is lighter than aluminium and just as strong. Some magnesium alloys have been a bit brittle, but this material is too new to give any long-term durability advice.