What is CFD
CFD (Computational Fluid Dynamics) is a way of looking at the airflow over an object using computer simulation models. This is a really common practice in many industries, but the most known is Formula 1, where aerodynamics is probably the most advanced of any industry.
Airo is developed to bring this highly advanced technology to cycling. The accuracy is incredible, and the cost compared to going to the wind tunnel or velodrome, it is a much cheaper option.
What can you Test with Airo
I've been aero testing for over 10 years, and the thing you learn very quickly when you start aero testing is that body positioning is your biggest lever for changing performance. The Airo App is the perfect tool for body positioning on a bike. Once you have the baseline pictures of the person and the position you can get the 'aero twin' into a very accurate representation of your athletes position. From there you are free to make the changes you think will lead to more speed and find the new CdA. You can also test different helmets in the Airo App, which is a massive advantage compared to the cost of buying and testing helmets in the real world.
What you can't test at present is equipment. In particular, bottle positioning in triathlon is very important for aerodynamics and currently can't be tested in the app. However, this maybe possible in the future.
Who Developed the System?
Ingmar Jungnickel has spent a decade in cycling aerodynamics, having led the aerodynamics department at Specialized Bicycles.
He is the 2018 US Olympic Committee Sports Science Coach of the Year.
Konstantin Usachev is Ingmars former colleague at Specialized and an experienced sotware systems developer.
Dr. Matt Williams added his tremendous experience as former lead CFD engineer at McLaren F1 and Bahrain McLaren in the development of the CFD algorithms
What Happens When you Book an Airo Bike Fit?
Here at WattsFaster we offer the Airo CFD testing as part of our top level bike fit. Combined as part of our bike fit, we do a baseline test in the current position, giving you a CdA to start working from.
Most people I've tested both with Airo and on the velodrome start with a CdA somewhere between 0.220 and 0.210, with a lower number meaning you are more aerodynamic. Occasionally, I see someone with a baseline closer to 0.200, and they are those that have already put a lot of thought and effort into their position/equipment.
How do we Make you FAST!!
Initially, the bike fit takes priority, as a bad position is always going to be slow and/or make running of the bike tough for triathletes. So we spend the necessary time to get the bike fit right.
Once we are happy with the bike fit, I do another CFD check with the new position and compare to the baseline. So far, at this point the new position has always been faster...however, it doesn't have to be, we have will begin to work on that with more focus from here.
Aerodynamics is very individual, so I don't use any set recipe, I look at the person in front of me and see where I think there are opportunities. Having done the bike for, I already have a good idea of what the bike and rider are capable of in terms of adjusting the bike and the riders flexibility. So I choose the most promising direction to start making changes, using the AIro App to check the CdA and the changes on the bike to make sure they stay in a good bike fit.
Optimizing for Speed
With the App you can actually test multiple directions of change in one go, so you can quite quickly see the changes that offer the most speed. For example, you can look if increasing or decreasing stack is better...and then follow the faster of the two to explore more and optimize. Or you can look if increasing or decreasing reach finds the speed and follow the faster route.
Bar angle is also something that you want to explore, and with some bikes being very difficult to adjust, you can check on the App if the CdA improves before changing the bike, which can save us a lot of time!!
With each change we can check the CdA and check if the bike fit holds. Also, we can check the rider is comfortable and can see in the new position.
Finishing the Airo Fit
At the end of the fit we get a great image from the app that shows all the variations we've tried. What is most interesting is how small the changes can be. However, the change in aerodynamic performance can be massive! As you can see on the right...the changes and what they do for the position on the bike, and the CdA.
Was you can see, we also went through a few helmet options too and found a good few watts there too.
What it Means
If we use the data above, the baseline was already very good (0.200) and the best combination gave us a CdA of 0.177. So if you ride an average of 250 Watts in a perfectly flat, windless Time trial of 40 km you would improve you finish time from 53 mins 33 seconds down to 51 mins 25 seconds....a MASSIVE 2 mins 8 seconds gain!! That's equivalent to 26 Watts improvement at that race speed.
Summary
Without the Airo App, you are just guessing at what is faster...with the App you can iterate a very fast position and have the confidence that it will translate to real world speed on the road.
If you want to find out more you can contact us be email or phone, or write a comment below...feel free to get in touch and see how we can help you find out WattsFaster :-)
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