Chris Froome of Team Sky

Sports tech: Cycling

To win the Tour de France a cyclist relies on a highly engineered road racing machine.

At its heart a bike is a fairly simple engineering enterprise: a frame for support, two wheels for traction, direct drive gears and chain for power, and handlebars to steer. But when it comes to professional road racing, the complexity multiplies.

Although injury has prevented Sir Bradley Wiggins defending his 2012 Tour de France crown when the race begins on 29 June, Team Sky will still field a strong squad including Chris Froome. The Kenyan-born cyclist, who rides for Great Britain, claimed a bronze in the individual time trial at the London Olympics last year.

The highly engineered machines that Froome and his team mates will race over the 23 days, 3,360km and 21 stages of Le Tour, are as far away from the road bikes that cycle the roads of the UK as a Formula One car is from a Ford Focus.

Much like a Formula One car, a professional bike is the sum of all its parts; chassis, wheels, tyres and gears. The frames raced by Team Sky come from Italian manufacturer Pinarello: the Dogma 2 chassis for road racing and the Bolide for time trials.

The Dogma 2 is the latest evolution of Pinarello's road racing bikes, taking over from the Dogma 60.1, which introduced the asymmetrical frame design. The thinking is simple. A bike is not symmetrical; the transmission is on the right hand side of a frame. Therefore the frame should be stronger and stiffer to handle chain forces on the side where they are greatest.

Using finite element analysis and lab testing Pinarello studied the forces acting on each side of the frame. The design of the Dogma 60.1 reflected this research with tube shapes and carbon fibre lay-up tailored to handle the forces acting on the frame.

The result for the 60.1 was different on the left and right chainstays, with more material where the right stay meets the bottom bracket, and a beefier tube toward the left-hand rear dropout. The top tube is shaped differently on each side, and the right fork leg is bigger than the left.

For the Dogma 2, this has been taken further with some additional changes made to improve stiffness and aerodynamics while saving 30g over the original Dogma. The biggest change is the new fork and head tube, which now uses a 1.5in lower bearing instead of the previous 1.25in. Increasing the size of the bearing means the steerer and head tube are bigger and therefore stiffer. That improves handling in corners and in straight line sprints, as well as making the front end stiffer against braking forces.

A completely new fork slips into the new larger head tube. The Onda 2 fork is more aerodynamic than the original Onda. It has a shaped crown, which fits into the down tube to improve airflow to the frame. Moving backwards along the frame, the down tube has been reshaped for improved aerodynamics and is asymmetrically shaped, while the top tube is slightly off-centre in a further development of the asymmetric design concept.

Internal routing for gear cables or wiring is a further aerodynamic improvement on the Dogma 2.

Better aerodynamics

For the time trials Team Sky will use the recently launched Bolide. In his victorious 2012 campaign Wiggins rode its predecessor, the Graal. Technicians went as far as to investigate the impact of air flow on every single component, reducing the total aerodynamic impact by 15 per cent compared to the Graal.

Aerodynamic improvements include the use of new airfoil tube sections and profiles designed to ensure the lowest aerodynamic resistance in all wind conditions to generate a forward thrust. In addition, the use of a concave back on the seat tube allows a closer position of the rear wheel, significantly improving the air flow in that area.

Complete integration of the brakes to hide them from the air flow greatly reduces aerodynamic resistance, while internal cable routing optimises the interaction between the airfoils and the air flow.

An integrated handlebar gives a unique continuity with the frame and greatly reduces the resistance, compared to a traditional stem and bar.

For the gear set, Team Sky will use Dura-Ace 9000 from Shimano. Riders have been using the electronic-shifting Di2 version designated 9070, on which there are several significant improvements as well as the overall mechanical bonuses, not least being a smaller battery hidden away in the seat tube.

The headline feature is the 11 sprockets on the rear wheel, but according to Dura-Ace engineer Takao Harada, the objective was to achieve more than just an extra gear ratio to choose from. "Every component is completely redesigned to achieve an overall lighter weight for the mechanical version under 2,000g, while improving the feel and shift precision of the gears; especially the front mechanism, improved modulation and mounting options for the brakes," he says.

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