Changing your posture on the road bike can instantly boost your efficiency more than 13 percent, according to a recent study from the Institution of Mechanical Engineers. The takeaway is simple: bend your elbows.
While studies on the aerodynamics of time trial positions have established the importance of a low tuck in pursuit of cheating drag, the recent proliferation of aero road bikes has shown that it’s not just the skinsuit and pointy hat wearing crew who are interested in maxing out their free speed.
The study by Barry et al, published in the Journal of Sports Engineering and Technology, looked at five different road cycling postures to see which best overcomes drag.
The outcome showed that gripping the brake hoods with horizontal forearms produced the smallest frontal area and equated to a power saving of 13.4 percent at 45km/h compared with sitting up with hands on the hoods. This equates to around 35 seconds over a 40km time trial at 300 watts. This horizontal-forearms position also offered a 10.3 percent saving compared with gripping the drops.
The study's findings correlate with BikeRadar's own testing done on the same positions using the CdA-measuring services of ERO Sports and Alphamantis. (Related reading: What is CDA?) In our one-rider study, CdA dropped from an average of 0.3473 when riding in the drops (position 2 above) to an average of .3167 when gripping the hoods with horizontal forearms (position 3 above).
Drop those elbows to lower your drag
The Institution of Mechanical Engineers tests were conducted at a yaw angle of zero degrees – i.e. head on, so it’s hard to know how this position is affected by crosswinds – and with one elite participant weighing 70kg, meaning not all body types may react exactly the same. However, given that 80 to 90 percent of a rider’s power goes towards overcoming wind resistance, adopting this more aero position should certainly help when riding, especially when riding into a headwind or downhill.
The findings also showed that nodding the head forwards resulted in lower drag, regardless of the position selected.
The study concluded: “As a recommendation for cyclist positioning, lowering the head and torso will generally translate to a reduction in aerodynamic drag by reducing the velocity defect and turbulence levels in the wake. However, to fully optimise aerodynamic performance, it is necessary to also bring the arms inside the silhouette of the torso and hips.”
While it’s hard to safely achieve this inside-the-silhouette time-trial position on a road bike, adopting horizontal forearms is the next best thing. It lets you keep your fingers on the levers, and you can rest your forearms a little on the tops of the handlebars. It’s a posture that can often be seen in the pro peloton, where riders select this pose during breakaways or when driving at the front of a group.
