What are road bikes made of?
In a nutshell
Bike frame materials have been revolutionised in the 21st century. Bikes were traditionally made from lightweight steels and alloys with carbon components or sections. These days, even though professional racing is now almost completely dominated by carbon fibre, that doesn't mean other materials don't have their place. This buying guide is here to show you the main features and advantages of the many different bike frame materials.
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Steel
When are steel bike frames used?
Steel is used on bikes ranging from simple single speed runabouts through to hand-crafted masterpieces from cycling’s most talented artisans. Many different bikes are made from steel or chromoly alloys.
Steel bikes often feature butted tubing – where the tubes used in the frame are made with much thinner walls at the centre to reduce weight. The ends have thicker walls, which increases strength.
How can I tell whether or not the bike is made from quality steel?
Steel comes in a range of different grades with the best steel road bikes made from stronger alloys and lighter frames. Good steel bikes are characterised by a ride that has a certain spring to it, something that comes from the frame flexing and moving underneath you, creating a uniquely comfortable ride.
Aluminium
What sets aluminium bike frames apart from the other materials?
Aluminium frames are characterised by big oversized tubes that look rock solid and early aluminum bikes had a reputation as being teeth rattlers. In the late 1980s and '90s, aluminium was the racers’ choice of materials.
Thankfully, over the years designers and engineers have improved and evolved aluminium to make the most of its lightweight characteristics while improving comfort levels. Bikes like Sir Chris Hoy's HOY Sa Calobra are a good example of this - offering great levels of comfort with a rigidity that can handle the power of the Scottish track legend.
Who develops and makes aluminium bike frames?
Companies including Specialized, Cannondale and BMC have continued to develop aluminium as a high-performance material and the best aluminium road bikes are able to compete on equal terms with the best of the carbon framed rivals.
Titanium
Titanium was once the most exotic material a bicycle could be made of. It has a similar character and quality to steel - light and lively. Titanium is impervious to rust, meaning Ti-framed bikes are usually given 'bike for life' status. Titanium frames are usually built using either 3AL/2.5v tubing or 6AL/4v. The numbers stand for the percentages of aluminium and vanadium alloys in the titanium mix, so in 3AL/2.5v the mix is 3% aluminium and 2.5% vanadium.
Are Titanium bikes expensive?
The short and obvious answer is yes. Compared to other bike frame materials, titanium bikes are going to set you back a fair amount, but for a ‘bike for life’, the price can normally be justified. In fact, both types of tubing were originally designed for use in space. They’re both highly-resistant to corrosion (even from the likes of seawater), have long fatigue lives and low weight.
To compare it with other materials, titanium is lighter than steel, stronger than aluminium and easier to craft than carbon. The adaptation of titanium for bicycles in everyday use is something that only modern engineering could accomplish, and it is one that is praised daily!
Carbon Fibre
What is carbon fibre used for in a bike?
Carbon fibre is without a doubt a modern wonder material. It’s used to make everything from bikes to race cars, to aeroplanes and yachts. Like titanium, carbon composites come from the aerospace industry and today carbon fibre totally dominates high-end bicycles. From frames to wheels, shoe soles to handlebars, seatposts and saddles – it is everywhere.
How expensive are carbon bikes?
Put a carbon race bike in front of any crowd and the first question is 'how much does it weigh?' The second will be 'how much does it cost?' Carbon fibre is a material where strands of carbon (fibres) are grouped and bonded together with a resin. Carbon is popular because it can be used to make strong and light bikes; however, that strength often comes at a high price.
What are the main characteristics of carbon bike frames?
Among riders, the most important bike frame characteristics will be weight, followed by stiffness and then compliance. It’s stiffness that’s important here and the best carbon road bikes will use high-modulus carbon in areas that need maximum stiffness e.g. the bottom bracket. Less stiff carbon will be used in areas where compliance and comfort are desirable, e.g. top tube and seat stays. The way carbon can be used to create light, stiff and compliant frames is what makes it such a popular material.
It’s worth knowing what the names and decals on a carbon bike mean - bike companies love a buzzword! Here's how to tell what's what.
Lay-up - How the carbon fibre sheets and sections are arranged before being bonded with the resin. Good designers will alter and adapt how the material is placed to get the properties they want from the finished frame.
Unidirectional (UD) - Carbon composite material where all of the carbon strands run in the same direction.
Woven carbon fibre - Where groups of strands of the carbon fibre are orientated in different directions and interwoven (like a basket). The angle at which the strands are interwoven also has an effect on how the material performs.
Modulus (high, ultra-high etc) - Young's Modulus (also known as Tensile or Elastic modulus) is a measurement of stiffness. It predicts how much a material will deform under load. A higher modulus means greater stiffness. But remember - a bike that's completely high-modulus might not be what you're looking for as it'll no doubt be rather rigid!
