How do you prepare best for a windy race, such as the upcoming Ironman World Championships in Kona, Hawaii? An interview with Swiss Side's CEO and Co-founder Jean-Paul Ballard:
1. What are the challenges on the windy bike course in Kona?
The aerodynamic forces on the bike and especially the wheels, can make it difficult for the rider to remain confidently in their aero position with constant power. If the rider raises from their aero position, or reduces their power on the the pedals, the time losses sum up quickly.
2. What is important to achieve best possible aerodynamic performance in windy weather?
The front wheel has the biggest influence because it impacts the rider position. Choosing an aerodynamically stable front wheel which is not nervous in gusty conditions is very important. Also choosing a rim depth which suits the wind strength. For example, there is only a 1W difference between our HADRON 625 and 800 front wheels but the HADRON 625 has 20% less sensitivity to the wind. Therefore for Kona, the 625 is a good compromise and can actually end up being the fastest configuration overall. On the rear wheel however, a deep section wheel is still ok and can actually have a positive effect on the stability (in Kona a disc rear wheel is anyway not allowed).
3. How important is your riding position and your equipment in windy weather (e.g. helmet, wheels etc.)?
The lowest possible sitting position (with the lowest frontal area) helps reduce the aerodynamic drag. However it’s important that this position is comfortable enough and rideable for 180km and that the running is not negatively impacted. So the sitting position is always a compromise. Having a good one-piece speed suit is very important in the wind, because good suits significantly reduce the aerodynamic drag. The wheels are extremely important and mentioned above.
4. How is aerodynamics changing in windy conditions?
The sailing effect becomes even more important. A good aero-bike and wheel combination can generate thrust which can reduce the overall aerodynamic drag by more than 30W! So a good aero frame and wheels bring even more performance benefit on a windy course like in Kona than normal.
5. Can Swiss Side simulate the wind conditions in advance and if so, what are the conclusions from the simulation?
Yes. We simulate the wind and the effect on performance. For our pro-athletes, we can tell them based on the wind conditions which wheel combination to ride. But for every athlete, the clear conclusion from the simulations is that aerodynamic performance is key. Even if the aero frame or wheels add significant weight to the bike setup, the time lost due to the extra weight is very small compared to the time saved with the improved aerodynamics. -Aero is King in Kona!
6. Whether headwind or crosswind: how much more power do athletes have to put into the bike course compared to races with no winds?
It of course depends on the wind conditions. With the right wind conditions (eg. 10km/h side wind), and the right aerodynamic bike setup, the rider will actually need less power for the same speed due to the sailing effect!
7. How can athletes save energy in windy conditions, what strategy makes sense on the bike?
The most important thing is to concentrate on riding in the aero position as much as possible.
8. What is the perfect preparation for the wind conditions in Hawaii - are there any?
Spend as much time riding your race setup as possible. Ride along a road where cars pass you so that you get used to the side wind buffeting as they come by.
Photo: Ingo Kutsche