IRONMAN has launched what is being billed as a comprehensive, multi-phase draft zone testing initiative in collaboration with RaceRanger and aerodynamics expert Marc Graveline.
The project aims to quantify the aerodynamic benefit of different drafting distances (12m, 16m, and 20m) to determine their impact on race dynamics and athlete performance. Testing is currently underway in Tucson, Arizona, using professional athletes and specialized instrumentation to collect objective data.
IRONMAN has recruited Marc Graveline, a leading figure in cycling aerodynamics and a retired tech executive from HP and IBM. Graveline is the founder of Notio, which created aero measurement systems, and he currently consults for World Tour cycling teams.
Testing utilizes ‘The Gizmo’, an aerodynamic sensor developed by Graveline that measures over 120 distinct inputs, including:
- Air speed and density
- Barometric pressure
- Road gradient and vibration
- Real-time Coefficient of Aerodynamic Drag (CdA)
The current testing phase in Tucson involves six professional triathletes performing runs at IRONMAN 70.3 race speeds.
- Baseline Data: A baseline CdA is established for each athlete individually.
- Group Variables: Athletes ride in various positions at distances of 12m, 16m, and 20m.
- RaceRanger Integration: RaceRanger sensors guide athletes to maintain precise distances and measure any variability.
- Positional Analysis: Riders of different sizes exchange positions to see how physical stature affects the power savings for the following rider.
2025 Drafting Trends
The initiative follows the release of 2025 IRONMAN Pro Series data, which showed that the integration of RaceRanger technology has helped to reduce drafting on the bike leg.
The data collected will be fed into sophisticated models to approximate power savings at various race speeds. IRONMAN plans to conduct in-event testing in early 2026 to validate these findings under competitive conditions.
The end goal is to establish an optimal draft zone distance that can be applied consistently across professional and age-group events. This could lead to updates in the 2027 IRONMAN Global Competition Rules, potentially affecting both the required distance and the time allowed for an athlete to complete a pass.
