Sleek and futuristic, the bike British cyclist Chris Boardman will pedal in the Tour de France is designed to slice through the air while its light, extra-stiff carbon fibre frame makes it very user-friendly.
Used by Boardman as a member of the GAN cycling team, the bike will be seen in the Tour's six-kilometre prologue, a time trial in Dublin city-centre next Saturday.
Ordinary bicycles are usually steel. Modern racing bikes are made of carbon fibre, a technology which lends itself to bicycle aerodynamics because it comes from research into aerospace design. It was originally used in jets and rockets to reduce weight and fuel consumption, explained Dr Conchur O Bradaigh, director of the composites research unit at NUI Galway.
Each carbon fibre is about the width of a human hair. The fibres can be moulded into smooth shapes, a process which is almost impossible with metal. Boardman's frame is carbon fibre which was glued, baked and moulded into one continuous structure called a monocoque frame, according to Mr Chris Field, managing director and chief designer of the British firm Hotta Design, which makes the bike for Boardman's suppliers, Eddy Merckx.
Metals such as steel and aluminium cannot be "profiled" into a distinct shape, but carbon fibre structures are easily moulded into unusual designs. The material's other main advantage is its strength despite its lightness, Mr Field explained. But the bikes can sometimes be brittle and do not absorb shocks too well, he said, which makes carbon fibre frames susceptible to crash damage.
Carbon fibre frames are best suited to time-trial races, where the cyclist competes against the clock. For races on the open road - there are two such stages during the Irish element of the Tour - carbon fibre frames would be too brittle, according to Mr Tim Higgins, development manager of Falcon Cycles Ltd in England.
But highly complex materials also go into the bikes used in open stages. Some are made from a composite metal matrix, where aluminiums are combined with other metals such as boron or beryllium to strengthen and stiffen them, Mr Higgins said.
Other frames are made from aluminium alloys, using up of 80 per cent aluminium and 20 per cent copper, or zinc or other metals, to increase frame strength.
The most expensive frame is one made of titanium, a light and springy metal which is resistant to bending, breaking and corrosion.
Aerodynamics are vital to time trials. A rider causes 80 per cent of drag, so the aim is to get the rider into the most aerodynamic position possible.
Time-trialists wear specially-designed teardrop-shaped helmets, also made from carbon fibre. "When a cyclist is standing, it looks like a spike is coming out of the bottom of the helmet, but when the rider is in an aerodynamic position this spike covers the gap between head and body. There is nothing to trap the air, nothing to disturb the air flow", Mr Field said.
For top professional cyclists such as Boardman the airflow is tested on the road and in wind tunnels. The cyclist and the bike are put in front of moving air and streams of a smoke-like substance is introduced. When the wind blows, small vortices, like whirlpools in the air, show visually where drag occurs. The team and rider can then make an adjustment in the cyclist's position and so reduce wind drag, Mr Field explained.