Technology plays a large part in cycling and one of the most important choices for riders of every level is frame material.
Manufacturers can construct frames from steel, aluminium, carbon, titanium, magnesium or even a combination. They can optimise tube thickness in different areas of the frame, can vary the way the tubes are bonded or welded, and as a result can control with great accuracy the way the bike will feel when climbing, its stability when descending and how comfortable it will be on a long ride.
Different materials have different weights, produce different riding characteristics and have different prices. In this section we’ll try to provide you with a very high level guide through the material maze.
Often called ‘the wonder material’, carbon is still relatively new when compared with its rivals, having been around since the mid eighties. It’s also the material that causes the most confusion as it can now be found at virtually all price points. Perhaps the most important point to note is that there is a huge variation in grades of carbon. Carbon tubes are constructed in layers mixed with resin. Cheaper carbon, which is often visually indistinguishable from higher priced tubing has a large amount of resin and often just a couple of layers of low grade carbon. This keeps costs low but makes the tube more brittle and fragile; these are generally the frames that you hear about breaking or offering harsh rides.
Better quality frames use different grades of carbon with stronger and lighter weaves that require far less resin in their structure - they also employ different "weaves" that align fibres in precise directions, and different fibre types that have varying levels of stretch, to specific areas of the frame in order to control the way in which the frame behaves under load.
One of the big benefits of a carbon frame is that it can be used to make tubes and lugs of almost any shape and size; this gives the potential to 'fine tune' different areas of a frame, such as a stiff bottom bracket area and compliant top tube. A stiff head tube can drastically improve acceleration and handling, while each tube can be stiff in one direction and compliant in the other. Lateral stiffness and vertical compliance alter ride quality, as of course does frame geometry and wheel/tyre choice.
Designs can vary from lugged tubes to single-piece monocoque construction, giving a huge variety in ride quality and performance.
For many of us ‘veterans’ our first bike was made of steel. Remember lusting after a Raleigh Record Ace and watching Team Banana in the 70’s? Reynolds 501 and 531 tubing? Well, steel is still around and for good reason. Mass-market children’s bikes and cheaper commuter cycles use low quality, heavy steel to achieve a very low price point and as a specialist road shop we leave this market to the high street stores.
However, high quality steel can still a great choice for the expert frame builder. It gives a 'classic' feel – comfortable to ride with a little ‘springiness’ which is particularly useful on the pock-marked British roads –and hence it is used in the construction of many audax and touring bikes. Surprisingly, a quality steel frame can weigh less than a medium range aluminium one. This is down to the way the tubes are ‘butted’ together, which allows for a light, quality thin-walled steel tube to be used. Steel is highly resistant to fatigue and is therefore very durable if looked after.
As aluminium is not as dense as steel, it makes for a generally lighter frame. It is easy to work/machine, keeping costs down. Different tube sizes, grades and mixes are used to give varying degrees of stiffness and strength. Computer aided design coupled to innovations in the manufacturing process have allowed frame builders to create tubes that can be one profile and thickness at one end and have completely different dimensions and thickness at the other, which lowers weight and enhances performance.This can change compliance and improve aerodynamics, using bladed tubes for example.
Aluminium tends to be used to make a stiff frame which is ideal for racing, as very little of your energy is lost, although often it is mated to a carbon rear end to soften the ride. Like steel, you can find cheaper aluminium frames in high street stores at very low prices but these normally give a very jittery and overly stiff ride.
Aluminium often suits heavier riders, where a more compliant material coupled to their greater mass would give an unacceptable loss of energy in the frame. It has the downside of a shorter lifespan than steel, but with modern production processes on the more expensive frames the gap is closing fast.
Titanium has always been seen as an exotic and expensive material. It is hard to work into tubes, weld and paint, leading to higher production costs and a tendency to be found in a natural bare metal finish.
Whilst cheaper titanium frames are finding their way on the market, the top-end frames sit in the highest price bracket of all. On the flip-side it has excellent corrosion resistance so doesn’t need painting which keeps the weight down. High quality titanium gives a good blend of power transfer, low weight and comfort making it a popular choice for long distance riding.
Two different grades of titanium are generally used, 3AL/2.5V and 6AL/4V; the numbers reflect the percentage mix of aluminium and vanadium. The former is slightly 'whippy' like a good steel frame and gives a relaxed ride while the latter can be made extremely light and stiff as large diameter tubing can be utilized without a weight penalty.
For someone seeking a frame with the comfort and durability of steel, the stiffness of aluminium and understated looks Ti is a tempting proposition. In any case, titanium can be a bike for life.