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The design secrets behind the bike that Wiggo rode to glory

Pinarello has published a white paper detailing aspects of the Bolide HR’s design that Bradley Wiggins' rode for his UCI Hour Record this evening.

According to Pinarello, the main characteristics of the bike are:

• Similar tubing sections to the existing Bolide

• Same geometry as the existing Bolide

• Aero-optimised fork and seatstays, which are very close to the wheel’s profile

• Aero-optimized front dropout

• 3D Printed titanium handlebar

• UCI approved

We ran a story earlier today showing some of the aerodynamic developments that Pinarello and Jaguar, co-engineering the project, had made to the Bolide and this new white paper gives us more details. 

Pinarello says that the main considerations in the design process were aerodynamics – the most important consideration because of the high speed involved – and the stiffness, to transfer the rider’s energy to the rear wheel.

The work on aerodynamics was done using CFD (computational fluid dynamics) simulations, with the road version of the Bolide as the start point.

The road Bolide (above left) has a fork with a nose that’s shaped to house the front brake but you don’t have brakes on a track bike so the designers had scope to alter that area. They say that smoothing the fork surfaces (above right) has led to a significant decrease in drag.

The designers could have widened the fork stance to increase the space for airflow and reduce drag in that way, but they decided to take a different approach, minimising the gap between the wheel and the fork legs to prevent air passing through.

The front dropout has been modified to reduce the detachment of the airflow, reduce turbulence behind the dropout and so to decrease drag.

Further modifications were made to other parts of the frame and the components, including the rear wheel and the handlebar.

“A further analysis was performed to check the aero performance considering the track characteristics (most velodromes today are 250 m long and the maximum banking is about 42°),” says Pinarello.

“The rider will spend almost half of the time on the curves, so the airflow will have also a lateral component, which is calculable. Again, using CFD, this condition was analysed and… the effect on the performance of the bike [measured].”

When it comes to frame rigidity, Pinarello says, “Increased stiffness… allows better power transfer to the rear wheel, without wasting energy by flexing the frame and therefore pulling the wheels out of alignment in every pedal stroke."

See, there's a reason we go on about frame stiffness in most of our bike reviews!

“Composite materials allow the production of very stiff frames, with a low weight; at the same time, a proper design and production technique could further increase the performance. Traditional frames, for cost and time reasons, are usually produced in two or more parts, then bonded together, because this method allows quicker and cheaper production. At the same time, the bonding areas require more material (to allow the overlapping of the parts), which means more weight and creates zone of possible stress concentration.

“To solve all these problems the frame is made as a one piece composite with no bonded parts after curing; this resulted in a light and stiff frame.”

The designers paid particular attention to the design of the handlebar because it has a major influence on the aero performance of the whole bike thanks to its position at the front.

“Behind the spacers for the arm rests, a low pressure zone is generated, because of the transition between the parts,” says Pinarello. “A proper design of this zone helps to reduce this, and consequently the drag.

“Standard technologies, such as CNC or carbon molding, would be excessively long and expensive to produce this particular shape, so we used an Additive Manufacturing method (also known as 3D Prining) to manufacture a titanium handlebar.

"In the additive manufacturing technique a high energy source locally melts the powdered material (typically metal), as defined by a 3D model, binding the material together to create a solid structure.

“The capabilities of this technology allowed [us] to produce a small batch of handlebars, everyone different from the other… This method will now be used to provide a similar service to Pinarello customers via the MOST parts brand.”

The white paper has now been published on Pinarello's website

Mat has worked for loads of bike magazines over 20+ years, and been editor of 220 Triathlon and Cycling Plus. He's been road.cc technical editor for eight years, testing bikes, fettling the latest kit, and trying out the most up-to-the-minute clothing. We send him off around the world to get all the news from launches and shows too. He has won his category in Ironman UK 70.3 and finished on the podium in both marathons he has run. Mat is a Cambridge graduate who did a post-grad in magazine journalism, and he is a past winner of the Cycling Media Award for Specialist Online Writer.