Here is the second article that Iñigo San Millán, Medical Director and Head Physiologist of Saunier Duval-Prodir has been generous enough to contribute. Bike photos just dont get any sexier than this, thanks again Iñigo

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In this contribution to NYVelocity I am going to talk about wind tunnel testing and the advantages a cyclist can get from that. Knowing that we were going to the Tour of California in February I mentioned to our Team Manager, Mauro Gianetti the possibilities of taking some cyclists to the wind tunnel in San Diego, CA., which had been used by Lance Armstrong in the last years with amazing results. This wind tunnel has helped developed many Boeing airplane models, as well as worked for NASA and US government for many projects. After Gianetti’s ok, I contacted Adrian Montgomery from Scott USA whose help was extremely valuable in putting me in contact with the engineers at the wind tunnel, with the logistiscs, reservations…etc.

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As I mentioned, last February right after Tour of California we travelled to the Low Speed Wind Tunnel at Allied Aerospace in San Diego, Ca. We took our cyclists from Saunier Duval-Prodir Simoni, Millar, Koldo Gil and Gomez Marchante. The testing lasted 2 days and it was a great experience and we got great data from that. We could see the 1st fruits of our wind tunnel testing benefits recently in the Tour of the Basque country where several riders arrived to final TT with the same time in GC and against all expectations Gomez Marchante took the TT and final GC. No one counted on him but we had a secret weapon. We knew that we had at least a 20-30 sec improvement in that TT and Gomez Marchante was 9 secs behind, so we where hoping that the modifications done in the wind tunnel could start showing off, and they did!

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How the wind tunnel works

The cyclist is on his bike tocked on to a surface that generates resistance in watts. In front of the rider is the “magic wind flow” of air where air is blown at the cyclist at 30mph, although if we wanted we could have set it to 380Km/h, but I don’t think the cyclists would have been very happy about that…The wind tunnel as a wind generator with a 2200 hp engine.

The test consists of several runs to see which position is the most aerodynamic. The 1st position is the basal position of the cyclist, that is his normal position when he time trials, and from there we started changing and playing around with different positions, handlebar measurements, helmets, skinsuits, head position…etc

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After basal positions we can for example lower the handlebars about 4 cm and see if that will improve cyclist’s aerodynamics, or look for the combination of lowering the handelbar 4cm and stretching the arm position about 5 cm. That is why we kept playing with different positions until we found a good one. The main parameter we looked at was the CdA (Coeficient of drag times Area). The lower the CdA the more aerodynamic a cyclist is. That is the number engineers have to target and bring it down as much as possible.

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Everything was supervised by the great knowledge and experience of engineers Craig Willet (aerodynamics Guru) and David Standford. We were very lucky of having their knowledge and experience in the field. I proposed a protocol to them using lactate readings to measure metabolic parameters on top of aerodynamic parameters. My theory was that some positions are the best aerodynamically speaking but maybe not so good metabolically speaking. For that, and with Craig and David’s input, I created a protocol so we could test all these measurements at once. I was really pleased to see the results. In fact, some positions, although being the most aerodynamic and having the lowest CdA, will have a metabolic cost by not being so metabolicly efficient. For some riders a stretch forward in arm position along with lowering the handlebars will dramatically reduce the CdA but will have a higher metabolic cost compared to a different position where CdA improvement was pretty good, almost as the best CdA found through the testing but also had a great metabolic response. So that would potentially be the best position for the cyclist in a TT. Other positions are very aggressive (for prologues) and will have a great CdA but bad metabolic response, but since we are talking about a 7-9 min effort the cyclist could afford that metabolic toll. Once found the best CdA, the engineers gave us a time savings table where we input the baseline Cda versus the new best CdA and amazingly we can see the time savings over one hour time.

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The wind tunnel room is completely sealed and locked and we were inside a room full of computers where we could see all the data obtained by the cyclist against the wind. Whenever a run was completed we opened the “submarine like” doors and I would jump up onto the surface where the cyclist was to get a lactate reading and run back quickly to my lactate analyzer to analize the blood lactate. In the meantime, and with the suggestions of Aerodynamics Guru Craig Willet, team mechanic David Fernandez would change the different positions for handlebars, arm and elbow supporters…etc. to find a new position to test against the wind.

We found out the huge amount of possibilities and combinations of different positions and materials you can do while in the wind tunnel to improve seconds. We only had about 4-5 hours per cyclist, and to tell you the truth, with a bigger budget we could have used at least one whole day per cyclist. No wonder why Lance Armtrong went every year and even for several days to finally achieve an improvement of 3’30” in a 1h TT!!!. Counting that there are 2 long TT’s in the Tour de France lasting about an hour we are talking about a theorical improvement of 7 min!!!. This data is not confidential because it had been aired to some media already. Unfortunately, I cannot disclose data we obtained from our cyclists but we were very pleased with it. We improved the position of all of our cyclists. Some improved more and some improved less, although as I mentioned before the different combinations of helmets, positions, handlebars, skinsuits, materials, shoes…etc are endless but will need lots of time and money!.

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Next and ahead of the wind tunnel testing there are many hours of TT training awaiting as well as some field and velodrome tests for the quest of the best position for a time trial, something crucial nowadays for any cyclist who wants to place well in a stage race.

Best Regards,

Iñigo San Millán, Medical Director and Head Physiologist.

Saunier Duval-Prodir UCI Pro Tour Team.