February 23, 2015 cburnham

Aero is Everything

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The office for the day.

In 2012 Specialized broke new ground for a bike company in building a brand new, state of the art wind tunnel specifically built for cycling.  With aerodynamics being one of the strongest driving forces in cycling product development, it made sense for the big “S” to build testing grounds in their own back yard.  I had the pleasure and privilege to spend a few days there over the last few years and each time it has been enlightening.

Both of these shapes have exactly the same drag even though the shape on the left is 20 times larger than the one on the right.

Both of these shapes have exactly the same drag even though the shape on the left is 20 times larger than the one on the right.

In January of this year I spent a day working on TT positioning and aerodynamics in the wind tunnel with Sean Madsen (bike fitter to all Specialized ProTour teams), and Chris Yu who runs the high-tech wind tunnel at Specialized.  While it is true you can’t generalize anything without testing in terms of aerodynamics, there definitely are a few general trends we were seeing and some interesting results with differing equipment.

  • As seen in many, including my own TT bike fit, a 1 inch handlebar height difference can be as much as 91 seconds difference in a 40k TT. Even more interesting, about 50% of the time lower was slower.
  • Even a slow position in the aero bars was significantly faster than road position or having your hands on the base bar. If you can’t maintain your aero position for 99% of your race than you need to change your position.
  • We looked at a lot of helmet configurations and a rider’s head position was the biggest determinant to what helmet would be faster. It was almost 50% that were faster in an Evade helmet versus a full TT helmet.
  • Getting narrower often didn’t change overall aerodynamics.
  • Head position seemed to be the biggest driving force in aerodynamics. A position with higher bars but allowed the head to drop below the shoulders was almost always faster than a lower bar position and higher relative head position.  The same goes for narrow, wider was faster if allowed the head to be relatively lower.
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We used the Retul Muve bike to quickly move through multiple setups.

This only scratches the surface to what we saw and learned in one day in the tunnel.  Having the ability to quickly move from one position to the other and see objective results is huge.  We are all a snowflake, and no one will see exactly the same results with the same changes, but following the above guidelines is a great place to start and what we use with our aero bike fitting process.

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Comments (2)

  1. Pokey Bill

    Head below shoulders? Pray tell me Chris, how does one navigate without sight? My neck is just not that flexible. Has anyone developed a mirror to allow better forward visibility?

    • I haven’t seen a mirror that would help but there might be a market for that! Flexibility is a big component in getting into an efficient aero-position. Everybody’s ideal position is a bit different due to limitations in range of motion and is something that has to be taken into account when dialing in the riding position.

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