Researchers advance aerodynamic understanding of paracycling

A team of researchers from across Europe have used a combination of CFD simulation software and wind tunnel tests to improve the understanding of the complex aerodynamics of elite paracycling.

paracycling aerodynamics
Irish para-cycling sprint team on tandem, Martin Gordon and pilot Eamonn Byrne, in wind tunnel of Prof. Bert Blocken, TU Eindhoven, Netherlands

Until now, despite the sport’s growing popularity, insight into paracycling aerodynamics has been very limited. But the new research, which has involved researchers from NUI Galway in Ireland, Eindhoven University of Technology in The Netherlands and Belgian research university KU Leuven has shown that decisive gains can be achieved by counter-intuitive postures and wheel selection.

Surprised by the scarcity of scientific research performed on paracycling, NUI Galway’s Dr Eoghan Clifford, a four-time paracycling world champion, joined forces with Eindhoven’s Professor Bert Blocken to set up the first large open scientific research project into Paralympic cycling.

The project combined computer simulation (CFD) with ANSYS software on Irish and Dutch supercomputers with testing in the wind tunnels of Eindhoven University of Technology and the University of Liège.

The investigation focused on tandem cycling and H1-H4 handcycling and resulted in four key new findings.

Firstly, the group found that the typical time-trial setup with a time-trial handlebar for the pilot and the stoker does not provide the lowest aerodynamic resistance. The stoker holding the seat post of the tandem bicycle (frame-clench setup) provides a gain of 8.1s over a 10 km race.

The research also discovered that the most aerodynamic race setup of the tandem cyclists is not the one where pilot and stoker bodies are closest to the horizontal. The pilot being slightly more upright gives a benefit of 6.5 s over 10 km.

paracycling aerodynamics
Para-cycling hand-biker Jetze Plat in wind tunnel of prof. Bert Blocken, TU Eindhoven, Netherlands

Furthermore the most aerodynamic wheel choice for a H1-H4 handcycle is not disk wheels at the rear, as commonly accepted, but two spoked wheels at the rear, because disk wheels would channel the flow between these wheels and create extra suction (drag) on the cyclist body. Spoked wheels at the rear and a single disk wheel at the front would save 16s on 10km.

Finally, for downhill handcycling, the research showed that athletes tend to adopt the so-called 6 o’clock position, with the hands in the lowest position and the arms tucked against the body. The 9 o’clock position with hands farthest upstream has a 4.3 per cent lower drag, which gives a gain of 0.8s over a 500m descent.

Commenting on the findings, Clifford said: “This has been one of the most exciting and challenging projects I have worked on. The extensive experimental and computational modelling work was unprecedented for Paralympic cycling and indeed for most sports. The work will fundamentally impact Paralympic cycling and will cause teams and engineers to rethink their approach to aerodynamics. This work also opens the door for world-class Paralympic athletes to have the same expertise and equipment available to them as other professional athletes. At the world championships and Paralympics where tenths of seconds can decide medals this work can unlock that vital time!”

Professor Bert Blocken, Eindhoven University of Technology & KU Leuven, said: “I am passionate about sports aerodynamics because it really pushes the boundaries of computer simulation and wind tunnel testing. In most topics on aerodynamics, accuracies of 5-10 per cent are considered sufficient. In sports aerodynamics however, tenths or even hundredths of percentages can be decisive. This first extensive open project in Paralympic cycling reveals new insights to obtain such gains in these competitions.”