When Filippo Ganna smashed the Hour Record last year, it was a triumph of both athleticism and technology. The INEOS Grenadiers rider covered 56.792 km in the hour, pulverising the previous mark by more than a kilometre.
Behind this achievement was, of course, the Italian’s huge physical engine, but did you know about the Aussie connection?
Engineers at the University of Adelaide played a key role in designing the Pinarello Bolide F HR 3D bike used in Ganna’s record-breaking effort.
Associate Professor Richard Kelso from the School of Electrical and Mechanical Engineering was there to witness history in that Swiss velodrome as a guest of Pinarello.
Inspired by nature, Kelso pioneered the placement of drag-reducing bumps (called ‘tubercles’) on the bike frame, which are known in the trade as ‘AeroNodes’.
“Bumpy leading edges can be found in several places in nature, including tubercles on the leading edges of humpback whale flippers and saw-tooth feathers on the leading edges of barn owls,” Kelso explained.
“The principle behind the tubercles is that they generate vortices that sweep around either side of the wing or tube, helping to keep the flow attached and ‘streamlined’. Without the tubercles, the flow may separate, or stall, causing the drag to increase suddenly.”
American marine biologist Frank Fish (yes, that’s his real name) first proposed that tubercles on humpback whale flippers produced a hydrodynamic effect in the early 2000s.
Tubercle technology has since been applied across a range of industries, including on the rear wings of Formula 1 cars, surfboard fins, yacht rudders, gas turbines, helicopter rotor blades, and on bicycle wheels produced by brands such as Zipp and Princeton CarbonWorks.
Kelso’s interest in tubercles began in 2006, where he employed a theory from the 1920s to describe how they worked. This led to him invent several wing modifications that achieved aerodynamic gains in fans and unmanned aircraft.
That was the start of a 12-year journey in which Kelso, his students and colleagues produced 25 academic papers, three PhD graduates, two patent applications, and a mathematical theory describing the wing modifications.
However, it was a casual bike ride that gave Kelso a flash of inspiration to take the wing technology and apply it to a bicycle.
“I was on a Saturday-morning ride with friends when I observed that each rider’s legs directs airflow from side-to-side past the seat post. Then I realised that the flow over an aerofoil-shaped seat post would separate, leading to greatly increased drag. It then occurred to me that flow separation could be minimised by the use of tubercles,” Kelso revealed.
After some initial low-tech testing – strapping bits of wool to his bicycle and fashioning rudimentary tubercles out of plasticene – Kelso realised he was onto something, and dived into developing a bumpy bicycle frame.
“The results were amazing,” Kelso said.
The development process continued as part of an honours project with students Henry Atkins and Shaun Fitzgerald, before the team was ready to take the aerodynamic technology to market.
The University, which owns the IP in the project, offered an optimised seat post design to Cycling Australia, which adopted it for their track bikes at the Rio 2016 Olympics. That was the only known use of the technology in the Australian context.
“Up until 2015 there was no industry collaboration, but the honours project that year, which was supported in-kind by Cycling Australia, was an opportunity to test the technology on a track bicycle. We appreciated the opportunity to have the technology displayed on the world stage, and we are reaping the benefits now,” Kelso said.
After Pinarello licensed the technology, that 2016 seat post became the starting point of a design that ultimately evolved into Ganna’s record-beating bike.
So, will we be seeing these cetacean-inspired humps on more bike frames soon?
Right now, it’s too expensive to apply the technology to all but the highest of high-end bikes. But Kelso believes that with a little further development, it’ll become accessible to most road cyclists and triathletes.
“The next step is to refine the layup process used to manufacture the tubercles on carbon fibre frames. This will allow the technology to be available for bicycles at most levels of the mass market,” Kelso explained.
In the meantime, they’ll keep pushing for more speed. Kelso says industry leaders are beginning to look for further gains by considering the bicycle and rider as a whole system, rather than optimising individual components in that system. For example, he says, they could place tubercles on the frame to account for a rider’s leg movements, as we have done.
This sort of approach has led to such radical designs such as British Cycling’s latest Lotus-Hope track bicycle, which has dramatically wide front forks,
“In some cases the drag of the bicycle itself may conceivably be higher than conventional designs, but the drag of the system is lower,” Kelso said.
Kelso said watching Ganna break the Hour Record on a bike he helped design was “incredible”, but also a massive relief; the ultimate proof of concept at the highest level.
“I was excited for Ganna and for my colleagues at the University of Adelaide and Pinarello,” he said. “It’s a big thing to see your ideas come to fruition at this level and to see years of work pay off.
“I was also relieved that Filippo had finally achieved a new record after a long build-up, and also that the tubercle technology was now proven on the world stage.”
Cover Image: Che Chorley