Wind Tunnel Visit

On Thursday Chris Pulleyn, Jim Vance and I went to the San Diego Low Speed Wind Tunnel with one of the cyclists I coach to fine tune his time trial position. Chris is the bike fitter from Bicycle Ranch in Scottsdale, Ariz., I have worked with for the last several years. He has set the bikes for nearly every athlete I’ve coached since 2005. At least I think it was 2005 when we started working together. Regardless, it has been many years. Chris is thorough to a fault and always focused on perfection whether the rider is a novice or pro.

Dave Sanford met us at the front door of the tunnel and, as always, gave us a historical tour of the facility. It’s always an impressive sight seeing those big propeller blades. It’s called the “Low Speed” tunnel because the top end for the facility is a 275 miles per hour wind. That’s appropriate for airplanes and Cruise missiles but we would be operating at 25mph.

After the tour we set about getting the bike ready. Chris had already done a two-hour fit on it back in January. We were here now just to make small tweaks to the set up. I’ve found Chris’ fittings to be quite close when it comes to aerodynamics. So I knew we would only make small changes. That’s exactly how it turned out.

The first order of business involved installing an adjustable stem so that we could move the aerobars into several different configurations without changing stems each time. This saved a tremendous amount of time once we got started. And at $850 an hour, time is expensive.

Once the bike was ready and being mounted in the tunnel by Dave’s assistants, Chris, Jim, Dave, the rider and I talked over the procedure we would use. Here is the process we had decided on earlier:


Step 1. Baseline. Conduct a base run using the fit as Chris had originally set it back in January. The first picture here shows that set up. This would serve as the standard by which we would judge all subsequent runs. Each would last one minute once everything was up to speed — wind and rider — but with bike adjustments and getting the tunnel ready each time wound up taking about 10 minutes per run. Chris worked quickly between runs to make the adjustments that follow.

Step 2. Front end height. Once we had a baseline we would begin to tinker with base handlebar and stem height. We would start by lowering the bars 1cm. If that produced a positive result (lower coefficient of drag) we would try 2cm lower. Any other changes in bar height would depend on what we found.

Step 3. Aerobar extension angle. Next we would tinker with the angle of the aerobars and arms in the extended position by increasing the angle 5, 10 and 15 degrees upward on subsequent runs. Later we decided to also try lowering the bars 4 degrees below the base position which was at zero degrees. At this point we also decided to rotate inward the arm extension bars at the grip end.

Step 4. Head position and helmet. Once the front end was optimally set we would experiment with head positions and helmets. Early on, however, we decided that his head position was quite good so didn’t mess around with this. He had brought another aero helmet with him but when he tried it on it was such a poor fit, sitting well up on top of his head, that we decided not to do a run with it. We had early on decided to tape over the vents in the helmet to see what benefits we might get from that based on an earlier recommendation from John Cobb. Since he competes mostly in 20k and 40k time trials this is unlikely to produce a problem. For 40k TTs in the heat he may not tape the vents.

Step 5. Miscellaneous. If we still had time (we had booked two hours) we would try anything that seemed reasonable based on what we had seen in previous runs. As it worked out we tried only one additional change – extending the handlebar reach by 1cm.

Notice that we didn’t intend to make any adjustments to the saddle position. This is what determines power output and we were convinced that Chris had fit this just right back in January when he had used the Retul device to originally set the bike.

The second picture here is the best position we came up with which reduced his coefficient of drag from the baseline run of 0.283 to 0.278 – a 1.8% improvement which translated into a 20-second savings in time in a 40k TT. That’s a small (and expensive!) gain which just goes to show what a great job Chris did in setting his bike initially. This was the second time Chris and I had set a bike and then visited the tunnel with one of the athletes I coach. The last time we shaved off 75 seconds, but most of this was head position and helmet. So Chris is pretty darned accurate at bike fitting when it comes to aerodynamics.

The final changes we adopted for this rider based on the wind tunnel results were:

1. Handlebars lowered 1cm. While at 2cm lower he had better numbers he also became obviously more unstable so this was not a good investment as it would likely reduce power and increase fatigue. His core strength needs to improve and once it does we can probably drop the front end a bit lower.

2. Bar extensions and arms angled 10 degrees up. At both 5 and 15 degrees his drag increased. But interestingly, at 10 degrees he had less drag. Lowering the bar extensions four degrees below the base also increased his drag.

3. Rotated extension grips inward. This lowered his time by about five seconds.

4. Helmet vents taped over. This took off about five more seconds.

Running and Core Stability

I’m still in the UK having spent the weekend at the TCR (Triathlon, Cycling and Running) Expo in London. I had a great time meeting people, attending some talks and doing a few of my own. On Sunday I sat in on a talk by a local physical therapist (called a ‘physio’ here). He had some great action videos shot of various runners of many different abilities. Each was running barefoot on a treadmill with a view from the back. I wish I had gotten his name and business affiliation but I failed to do so as I got there after the introduction.

The first video he showed was of a sub-2:20 marathoner who had been running for several years. This runner certainly had what could be called ‘excessive pronation.’ Shortly after footstrike, which appeared to be fairly midfoot, his foot collapsed medially (to the inside) quite a bit. Yet when the video was freeze framed at this point and advanced one frame at a time there was no medial collapse of the knee. In fact, the knee and leg held a straight line from the hip to the ankle. That is unusual for a runner with such an extreme amount of pronation. Maintaining a straight line from hip to ankle means that the core muscles must be quite strong to keep the hip from dropping as the recovery leg swings through. If the hip drops the knee must collapse to maintain balance. With this runner, again being viewed from the back, the waistline of his shorts remained perfectly horizontal. That was because his core muscles kept everything nicely in place. So despite an excessively pronated foot there was no medial or lateral stress being placed on the leg, knee or hip. And, in fact, this athlete reported that he had never been injured despite many years of running.

Another video was presented in which a young female runner was viewed from the back as she ran. Her foot and ankle movement were nearly textbook with the ankle showing only a slight amount of pronation, which is considered ‘normal.’ However, she reported a significant history of iliotibial band (ITB) injuries. It was obvious why this was the case. As her recovery leg would swing through the hip on that side collapsed and the knee of the support leg buckled in considerably as a result. Going farther up the chain it was evident that her core muscles were quite weak because the waistband on her shorts rocked up and down pivoting around her SI joint region.

The bottom line of his presentation was that the core muscles are at least as critical to running stability and performance as are the feet. He gave an excellent presentation and much food for thought. I only wish I had gotten his name.

Basic Training Assumptions

Even though I just said below to expect a gap in posts here, while on the plane today I had some thoughts about basic assumptions regarding training for endurance sport. These certainly aren’t earth-shaking thoughts but they lead in a direction that perhaps you hadn’t thought of before. So I thought I’d share them with you before my next flight.

1. Training must be physically stressful. The whole purpose of training is to physically and appropriately challenge the body. From this challenge the body adapts and becomes more capable of handling a given level of stress. To be effective the training challenge should be specific to the stress anticipated in the goal event for which you are training.

2. Adaptation to a specific physical stress is called “fitness.” This puts to rest old arguments about who is more fit - a golfer, weight lifter or marathoner. Each is equally fit for the unique physical demands of their sports. For example, if you want to define fitness as the physical skill required to hit a ball a long way with a stick then the golfer is the fittest.

3. Another product of stress is fatigue. If you challenge the body many physiological changes other than fitness can occur. You may have depleted carbohydrate stores, damaged muscle cells, altered body chemistry, etc. Taken as a whole these changes are called “fatigue.”

4. Fitness and fatigue trend similarly. You may not have thought about this before, but it is important to understand. There is a strong link between fitness and fatigue. If you are fatigued from training then you stressed the body adequately enough to create the potential for fitness. If the workout did not cause any fatigue at all then it also did not produce the potential for fitness. So, when fatigue is rising you can expect the same thing from fitness.

5. In order to race well one must reduce fatigue. This is what tapering before a big race is all about – reducing fatigue. You don’t want to go into important races tired. There is no benefit from doing that. Racing when tired most assuredly will produce less-than-stellar performances.

6. Reducing fatigue is called “coming into form.” The term “form” came from late-nineteenth-century horse racing. Before placing a bet you would check the form (sheet of paper) provided by the bookie which showed how each horse had been racing recently. When a horse was racing well it was said to be “on form.” Bike racing which started in the late nineteenth century adopted this term early on. In recent years other endurance sports have begun using it.

7. Coming into form requires losing fitness. This is where I was taking you with the above assumptions. Don’t believe me? Then go back to #4. The bottom line is that you must give up some fitness in order to shed fatigue and therefore race at the highest levels. The trick is to limit and control how much fitness is lost in the tapering process. I’ve probably put more time and thought into this single aspect of race preparation than any other. But what I do is far from perfect. Peaking is as much an art as a science. The protocol I use isn’t 100%. This is described in my books. It may work for a given athlete for one race but not as well for the next. That’s because we are humans and not machines. There are many variables in our lives. Actually, I’m glad it’s that way.

TrainingBible Companions & Travel

I just received word from my publisher, VeloPress, that the Companions for the new editions of the Training Bible books have been delayed. They are not certain yet of the release dates. The Companions are smaller books which are just the updated materials in the new Triathlete's and Cyclist's Training Bibles. That way you don't have to search for the changes in the newest editions. They will also be much less expensive than the new full editions. When I know more I will let you know.

Also, I leave today to speak at the TCR Expo in London and will be on the road for 8 days. Expect a gap in postings here as a result. Back to something close to normal late next week.