cycle frames

Aluminium is roughly one-third as dense as steel, and so a frame made of tubes the same diameter and thickness as those of a steel frame of corresponding size would be a third of the weight. Aluminium, however is not as rigid as steel, so the frame would flex far more. Aluminium is also more prone to fatigue than steel, so it would have a shorter life. These problems can be overcome by using tubes of grater diameter, with slightly thicker walls, and in so doing, it has been possible to create aluminium frames lighter and stiffer than their steel counterparts.

Innovation in tube design, welding technology, heat treatment and alloying of aluminium with other, more exotic materials has made aluminium alloys more and more popular choice for commercial framebuilders. Early 'oversize' aluminium designs, made to optimise tube and frame rigidity and therefore power transmission, suffered from harsh riding characteristics, but these too have been largely engineered out.

Durability has also improved immensely over the past five or six years or so, but it is unlikely in the upper echelons of quality that aluminium alloy frames will ever equal steel. However, the very lightest steel frames do still have a relitavely limited life, in the same way as the lightest aluminium alloy frames.

As for which to favour in a frame, it is as with many things in cycling, there is, after a certain price point, no 'better' or 'worse', just more or less suitable to a given use.