Ok so first up, some of you may be wondering why I’d go through all the expense and trouble of having a wind tunnel session when I’ve never owned a TT bike before, let alone ridden one. The fact of the matter is that, to cut a long story short, the bike was heavily discounted, and came with a free wind tunnel session. It was never my intention to have any aero testing, but if you’re offered a free session at the most advanced wind tunnel in the country……you’re not going to say no!
As it caught my by surprise, I had to buy a skinsuit (to make the most of the session), so I took advantage of the Le Col Strava £50 discount, and purchased their suit. It seemed to fit really well, and the guys at Boardman had not seen it before, but commented that it seemed like a nice suit, especially for the money.
The session I initially had was the foundation aero session, which I think gives you 30 mins in the tunnel, but the guys at Boardman upgraded me to the Focus Aero session, which is normally £350! The total time is around 90 mins, with 60 mins in the tunnel. Upon arrival, the guys were great, showing me around my new bike and establishing a bit of background on me to make the session as relevant as possible. Of course, I had no TT experience at all, which they were totally fine with, as they cater for all abilities. They said they also enjoy the challenge of starting from scratch, and seeing how many watts they can save even in one session.
I was shown upstairs to their fitness testing labs, and the entrance to the tunnel. I was a little nervous, everything was very clean and clinical in a sense. After being shown to the changing rooms I felt like I was prepping for a hospital operation!
We wasted no time in getting in the tunnel and set the bike up on the rig, and I was given a quick brief of how it works and what to expect during each of the recorded runs. This tunnel essentially works by having the huge fan behind you, and the air is sucked past you through a series of tiny channels, to make the air as smooth and flat as possible. In front of you is a vast black space (through which the air is sucked) and a projected screen on the floor. This shows yourself, from camera feeds placed in front, above and to the side of you, as well as your cadence (which you try to keep as similar as possible), and most importantly your live drag reading, displayed in Newtons.
Run 1 was a simple baseline test. After setting up the seat and bars, I was told to just sit on the bars in a comfortable position, and we’ll take a reading of that. Unfortunately the earpiece they gave me wasn’t working very well, so they displayed messages to me on the projector – simple instructions such as ‘hold that position’, ‘get ready for a recorded run’ etc. The recorded runs last about a minute, and you just focus on a spot at the end of the tunnel which replicates where you’d be looking on the road.
You are incredibly conscious of trying to move as little as you can (apart from pedalling obviously!) There were times where the drag figure would fluctuate a little even though you’d swear you weren’t changing position.
Run 2 was to be as aero as possible, tucking down and keeping my head as low (and comfortably) as I could. The ability to see the drag live was amazing. Even adopting this position, the drag needle dropped quite significantly. It was not the most comfortable position to hold, but the guys said that because of this data, it was obvious the bars needed to be lowered.
This tunnel also allows really effective live testing, and the technicians can be almost stood next to you (out of the airflow), and he can tell you to try this and that, and we both watch the drag needle either drop or rise accordingly.
Run 3 was the same as above but with a longer reach. Note the position of my elbows on the pads.
We did another recorded run, which confirmed that the dropped bars position was a major improvement. It was also much more comfortable, and didn’t strain my neck at all.
We experimented with this setup for a bit, and it became immediately obvious again that reaching forward even more (which still felt comfortable) made even more improvements.
Run 7 was a simple swap to a common aero helmet. They had loads to chose from, but they said this was a common starting point and it works well for most people. Some of the really fancy super aero looking helmets actually perform quite poorly on some people I was told! I would have loved to try different ones to know which would be best for me to buy but sadly we didn’t have time. Getting the position right was the primary focus.
For run 8 I was told to rest my hands on the top of the bars to replicate a higher degree rise on the bars. This felt more comfortable, and actually improved aerodynamics too.
The last mechanical change was a quick swap to some Zipp bars with a 30 degree rise. These felt really comfortable, and it confirmed the position in the previous run.
For my final run (10), I was told to again rest my hands on the bars and extend further forward. Unfortunately they didn’t have a 40 degree rise set in the ‘lab’ so this was the best we could do, but it was enough to confirm that a) I need to buy a set of 40 degree bars and b) it was the lowest CdA reading of the session.
These three front on shots also show the huge different between the first run, the dropped bars, and the final position of the session.
Here’s a quick GIF made from the above images. I found it really useful flicking back and forth between all the images, and this displays that really well.
This table (click to enlarge) shows all the figures from the various runs shown above (and a few that I didn’t include images of). There were two baseline tests, and then you can see a huge immediate drop when forcing myself into the lower (and very uncomfortable) aero position. The runs were fairly even after that as we established the best and most comfortable positions for my hands. After switching to the Giro helmet, and swapped to the Zipp bars, the CdA figures start to drop considerably again, with the 40 degree simulated position being the lowest of the session (and quite a jump from the previous run too).
The table on the right shows the wattage saving, assuming a 385W power output (which is around my 20min power) and approx 45km/h. In a nutshell, they saved me 58 watts and over 3 minutes on a 25 mile course! Not bad for some simple adjustments! Even just dropping the bars and riding in the more comfortable lower position saved 30W alone. I’m sure more watts could be saved with a more dialled helmet, and perhaps and more effect skinsuit etc, and maybe shaving my legs!! (not that that’s ever going to happen!!!)
I’m still getting my head around this graph!
A final summary of the results and changes made for each run: