We all know there is no replacement for training, but the truth of the matter is we need a bike in order to do a triathlon. That bike can be a cheap “banger” or a state of the art aero weapon that costs more than many people spend on cars. Often our equipment choices are based on budget, marketing promises or just plain looks. When it comes to tri bikes aero is the word most used to describe the new whizz bang frames, but without a wind tunnel of our own we are left to try and decipher the information that manufacturers choose to show us. The marketing departments of each manufacturer appears to have mastered the art of manipulating aero data to show under which precise circumstances their frame is more aero than all the rest. While this seemingly endless arms race goes on we are often oblivious to the fact that the biggest contributing factor to aero is the big hunk of flesh that sits atop your frame of choice.
Up till now aero testing has been nigh on impossible, most of us were left to use the good old “eyeball aero” test which was based around the shapes that we believed to be aero. Sure there were some tests and calculations that could be done to estimate aero but they all had shortcomings especially when it comes to the finer details. Power meters have helped this process slightly making other testing protocols possible, but it is power meters in conjunction with some fancy new technology that makes accurate repeatable data possible, affordable and available to people who don’t have access to a wind tunnel.
Most of us who have read any of Alex Simmons’ posts on Transitions know that when it comes to power, Alex is the “go to guy”, he knows power inside out and he is a stickler for detail. So if ever there was a person who you would want doing your aero testing Alex is the man and his Aerocoach business is set up to do just that.
I headed out to Sydney’s Dunc Grey Velodrome to see Alex put a few athletes through the “Aerocoach” process. The velodrome itself is an impressive facility and as a few of the athletes being tested had never ridden on a track before it looked like the initial excitement was simple the joy of riding an Olympic facility and having a world class velodrome all to yourself. Once everyone has had time to familiarise themselves with the intricacies of track riding it’s time to get down to business.
A pair of athletes is set up simultaneously with the idea being that one is riding while the other is tinkering with setups or swapping out equipment. The bikes power meters are checked and paired, a high tech gadget is attached to the bikes and Alex fires up the computers. I won’t try and explain it in detail, best to defer to their website which states.
RTAA™ combines the data provided by a cycle power meter (e.g. SRM), a wheel speed sensor and the Aerostick, and transmits to a computer for real time analysis, display and recording of CdA (aerodynamics) and/or Crr (rolling resistance). For indoor testing, due to the controlled conditions Alex says he doesn’t need to use the Aerostick, which his Aerocoach colleagues use during their outdoor testing in the UK.
Alex explains that the system is so accurate that it can track the exact distance that has been travelled around the track, the black line at Dunc Grey is 250m, but any deviation from the black line changes that distance and the software can track that to within seemingly millimetres.
So it’s on with the testing and our athletes head out on to the track and roll around at what would be their normal race pace. The process of checking sensors and getting baseline data is critical to the process as an accurate baseline is where all the following calculations are based on. Alex explains that the system is reliant on good quality power meter data, and any problems with power meters are pointed out to the athletes (it is always a good idea to make sure yours is working properly beforehand). Alex tells me he expects to supply his own meters for testing in future, which means anyone can test and Alex can be assured of data quality.
Alex crunching the data
Once the base line is set the clients are free to start changing items as they feel the need. Alex will provide feedback on each setup and in turn ask for yours in relation to comfort and any effects of the change, bearing in mind that different athletes have different events they are training for and the level of comfort or discomfort that you are willing to bear will depend on whether you are doing a track time trial or an Ironman and that needs to be considered.
While the rider is circulating the track, the real time data is plotted and aerodynamics calculated instantly:
And summary data is provided lap by lap:
Alex then plots results in a chart as the session progresses to make the impacts quick and easy to spot:
Later, Alex reviews the data, adds additional commentary and recommendations based on the testing and provide a report showing all the relevant data, testing information and any images or video captured, as well as what these aero impacts equate to in time savings over various distances and at various power outputs.
The trend in aero helmets has changed recently. Long tails were all the rage a few years ago, then shorter tails hit the scene and now even road aero helmets are being worn in races against the clock. The truth is no one helmet suits everyone and sadly this probably means the one you own, you think looks the coolest, or is the best colour match for your kit is probably not going to be the most aero helmet for you. You need to be open minded, have a few helmets at your disposal and rely on the data. AshleyS was pretty aero on his baseline runs, he looked good and comfortable and strong. He was wearing a Giro Advantage helmet which was sitting pretty flat on his back and “looked” quite good from an “eyeball” perspective. He then tested a Kask Bambino; a helmet many “think” is faster but actually tested slower for Ashley. He then fortuitously had the opportunity to test a Giro Selector which proved to be the fastest helmet on the day. How much faster? Well by Alex’s calculations about a second per km. That’s 3min over an Ironman!
Ashley also tried a quick “cable tied” behind the seat bottle holder and despite what we have all been led to believe it proved that for Ashley there was almost zero aero penalty for carrying the bottle. A further test of dropping the bars to get lower, something that we assume is more aero, proved to provide no aero benefit but negatively affected Ashley’s comfort on the bike and with an Ironman bike leg to consider comfort is a big factor.
So what then are the benefits of accurate aero testing?
Well, if you have a decent position and have that confirmed as being as aero as you can be, then as Ashley confirmed, that in itself is will take away any lingering doubt about your position and is worth having confirmed. The rear bottle holder, while not yet part of Ashley’s race plan, was something he wanted to have in his box of trick should he rethink his nutrition needs and hydration positioning. Again, having this confirmed as a zero penalty, means a last minute change of mind with adding or leaving off the bottle will have no mental anguish attached.
Further to this the purchase of a new helmet could net Ashley another 3 minutes in an Ironman bike leg. Is 3 minutes important, well if you miss Hawaii or an age group podium by 2 minutes then Hell yes!
So bearing in mind Ashley was already pretty aero and had minimal gains to be found in position there were still 3 minutes to be found in tweaking a helmet choice , so for those with less slippery positions larger gains are certainly possible and could be money well spent.
The testing is certainly easy for the athlete to do, they just ride their bike around the track for a 2-3 minutes at a time and hold their position. The hardest part is making equipment adjustments! The feedback is available immediately, and so testing priorities can be modified during the session. The big benefit of this style of aerodynamics testing is that the rider knows pretty quickly if a position or equipment choice is rideable for them, or whether they think they could adapt to it with enough training.
Alex tells me he is looking to provide the service beyond Sydney, and has already set up a partner to deliver the services in Perth, and he will be looking to do similar in Melbourne at some stage.
Video of system in action: https://www.youtube.com/watch?v=PjRBhsODirY