The findings of a recent study from the Institution of Mechanical Engineers could instantly boost your cycling power by more than 13 percent, just by changing your posture.
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 arms horizontal position also offered a 10.3 percent saving compared with gripping the drops.
The small improvement in aerodynamics between the upright-hoods and drop-bar positions increased when adopting a ‘crouched’ position while in the latter posture, the power requirement dipping by seven percent.
The tests were conducted at a yaw angle of zero degrees – i.e. head on, so it’s hard to know whether 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 90 percent of a rider’s power goes towards overcoming drag while travelling at 50km/h, adopting this more aero position should certainly help when riding, especially when cycling into a headwind or downhill.
The findings also showed that nodding the head forwards resulted in increased drag regardless of the position selected – though the specific design of the standard road helmet used in the test could have an effect here.
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 achieve this inside-the-silhouette time-trial position on a road bike, adopting horizontal forearms is the next best thing. It’s also a posture that can often be seen in the pro peloton, where riders naturally select this pose during breakaways or driving at the front of a group when unable to hide in the pack.
via BikeRadar.com http://ift.tt/1vEPm3q
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