Wind Tunnel Testing
By Neil Shirley, Kelly Benefit Strategies Professional Cycling Team
1/29/10 - I recently had the opportunity to do something that I’ve been hoping to do for the past few years but have never had the resources to make happen until now.
Kelly Benefit Strategies flew seven of my teammates and me to North Carolina to visit the A2 Wind Tunnel for two days worth of aerodynamics testing on our new Orbea Ordu time trial bikes. I’ve known of the benefits that can be gained by wind tunnel testing, but due to the high cost it’s been something that was impossible for me to justify spending my own money on. Fortunately, KBS saw the advantages and decided to make the investment for a handful of us to have our positions tested in the wind tunnel.
I had just recently received my Orbea Ordu time trial bike so I set it up based off my old position. I found this position by setting the bike up to be UCI legal first off. Then, within those limitations I tried to mix aerodynamics with comfort. It was a fairly standard position, nothing extreme. I’m not a super flexible person so I definitely had some limitations on how extreme of a position would work for me.
Neil Shirley (Kelly Benefit Strategies) tests his time trial position at the A2 Wind Tunnel.
Photo Courtesy Neil Shirley
It was finally time to see how my old position fared in the tunnel and see what adjustments I could make to gain either a power or aerodynamic (or both) advantage. We had Dino from HED on hand as our aerodynamics guru. He’s been in the wind tunnel with just about every top Pro-Tour team as well as Olympic and World Champions.
Once in the tunnel my original position was tested as the benchmark and then it was time to make some adjustments.
Over the course of two hours my position went basically full-circle. We dropped the stem to start with and then raised it in small increments, testing with every minor change. Then we tried a longer stem followed by a shorter one. Next was the angle of the aero bar extensions, from flat, all the way up to the maximum angle allowed by UCI. Next was elbow width. Finally, we tried different aero bar extensions: s-bend, ski bend and straight. Once all the data was in it was time to make some decisions.
Neil Shirley's position in the wind tunnel is analyzed to determine the best time trial position.
Photo Courtesy Neil Shirley
In the end there were a few notable changes. The first change was an interesting one. We actually raised the stem by 10 mm since the testing had shown no increase in drag compared to the lower position. So, being a little higher in the front opened my hip angle, which will allow me to produce more power without sacrificing aerodynamics. The biggest gains started with my elbow position being narrowed substantially. We adjusted my Vision Tech armrests all the way in towards the stem to where my elbows were nearly touching. The narrowing of my elbows had a dual purpose, partly aerodynamics of my elbows but more importantly it enabled me shrug my shoulders more comfortably. By shrugging my shoulders up towards my ears I was able to make the biggest aerodynamic gains. With the shrugging technique alone I was able to take multiple inches off of my frontal area, which equated to over twenty watts of power. Finally, after trying all three different types of aero extensions we went back to what I started with, ski bend. There was no real difference in aerodynamics for me between the three so it ultimately came down to comfort and preference.
I was able to learn a lot with my time in the wind tunnel. With the changes made to the bike and learning the shrugging technique I’m hopeful that it will pay off at the races. Probably the biggest improvements will come from my newfound motivation to train on the time trial bike and the confidence of knowing that I am in the most efficient position for me. With the racing season already upon us I’ll be able to put my new position to use sooner rather than later.
Neil Shirley
Kelly Benefit Strategies Professional Cycling Team
