Cycling Joins The Aero Club
The 2015 Tour de France is in full swing and it is abundantly clear that aerodynamics has risen to be the primary technological focus of the event. Just like the aerodynamic transformation of Formula 1 (F1) that took place in the 1960s, cycling is now pre-occupied with all things aero. Unlike F1 the concern for cycling is to minimize drag, whereas the realization in F1 was that downforce, not drag, was the key to improved performance.
Why is there such a focus on drag reduction in cycling? Recall that the power required to progress through air and counter the opposing drag force scales according to the velocity cubed, i.e., to double your speed you have to increase your power by a factor of 8! So there is a massive incentive to reduce the effect of drag given that power has to be generated by a human engine.
Bicycle manufacturers and certain well funded cycling teams have deployed significant resources in a secretive technological race to win bicycle races. And whenever you want to better understand airflow you will most likely find Computational Fluid Dynamics (CFD) and wind tunnels not far away. Therefore, it should not be a surprise that CFD and wind tunnels are mainstays of various efforts to assess ways to minimize drag to make bicycles faster.
The most apparent effect of drag reduction is in the time trial equipment you will see at the Tour de France. I say equipment because it is not just about the bike - increasingly clothing (especially the helmet) are integral components in the drag reduction effort too. While time trial equipment is an obvious manifestation of technology to minimize drag, less obvious is that the regular bikes in the peloton used for the majority of the racing are anything but regular.
Within the constraints of the Tour de France governing regulations (UCI rules) there is also scope to deploy more subtle drag reduction technology for regular race bikes. This follows the same lines as time trial equipment but usually with a twist. You will see:
- Aero bikes with truncated airfoil sections (in accordance with the UCI rules governing frame 'tube' aspect ratios) and integrated brakes shielded from the wind (but no fairings in accordance with the UCI rules).
- Various depths of wheel rims to minimize the wheel drag and under certain conditions aid further drag reduction in cross winds (yaw).
- Tight fitting clothing (to avoid parachute-like drag) with strategically positioned special textures to promote laminar and turbulent (think golf ball-like drag reduction) flow regions.
- Helmets that seek a sweet spot between drag reduction (smooth) and adequate cooling (vents) for long rides in the heat of summer.
Previously it was the case that with an aero bike you'd pay a weight penalty, thus reducing its appeal amongst weight weeny cyclists. However, in recent times bicycle designers have found ways to keep weight in check and still incorporate drag-reducing features. This effort has been aided by UCI rules mandating a minimum bicycle weight, which means the latest aero bikes can match the weight of standard non-aero bikes, so it is increasingly easy to prefer an aero bike with its wind cheating benefits.
So where is this technological race going? Look no further than the myriad of aerodynamic regulations for F1 in that increasingly we will see more more regulations governing aerodynamics in cycling in an effort to improve safety through reduced speeds. At this point CFD and wind tunnels will be even more important in order to eke out marginal gains in aerodynamic performance.