With Ironman 70.3 Switzerland in Rapperswil-Jona just around the corner, athletes are finalizing their race-week preparations. Rapperswil is famous for its stunning scenery, but the bike course is a masterclass in varied, undulating terrain. It presents a classic mental challenge for competitors trying to optimize their race: Is it better to choose a lighter, more nimble road bike for those punchy Swiss climbs, or go full aero with a triathlon bike? And how should you manage your power so you are as fast as possible without destroying your legs before the run?

To separate transition-area myths from real-world physics, we ran a study of the Rapperswil bike course using the Swiss Side Performance Platform, answering the main questions around equipment selection (Road vs Tri Bike) and pacing (how to distribute your power over the course).

The Course Physics Profile

• The Distance: Approximately 90 km (2 loops of 45 km).

• The Profile: Hilly, rolling terrain with approximately 1,100 meters of total elevation gain.

• The Key Sectors: A flat 10 km roll along the lake, followed by the vicious, punchy Witches' Hill (Hexenberg) featuring gradients spiking up to 12–13%. This transitions into a short reprieve before hitting the long climb up to Goldingen called “The Beast” with an average gradient around 5%. From the top, athletes face a blistering, fast descent towards Ermenswil and Schmerikon before returning to the flat lake section.

For this case study, we modeled a standardized age-grouper profile (70 kg rider, 180 cm) targeting a Normalized Power (NP) of 220W to see how equipment choice and pacing execution affect the clock.

We used the pre-segmented course in the official course database of the Swiss Side Performance Platform and made use of the automatic wind forecast to get recommendations that are tailored to the conditions on race day (June 7, 09:00).

The Gear Battle: Road Bike vs. Tri Bike

Many athletes look at a course with 1,100 meters of climbing and instinctively reach for a lightweight road bike. Our virtual head-to-head, using the platform's Equipment Comparison functionality, found that a dedicated Triathlon/TT Setup is approximately 5 minutes and 30 seconds faster than a high-end Road Setup.

Metric	Setup A (Road Bike)	Setup B (Triathlon/TT Bike)	Delta
System Weight	Lower (7.0 kg bike)	Higher (9 kg bike)	+2 kg Weight Penalty
Aerodynamic Drag (CdA)	Higher (0.400 hoods / 0.300 drops)	Lower (0.320 base bars / 0.250 aerobars)	Significant Aero Advantage
Estimated Simulated Finish Time	02:42:43	02:37:13	TT is around 5min and 30s faster

Platform Insight: While the lighter road setup claws back a tiny handful of seconds on the steepest ramps, it gets heavily penalized everywhere else. The TT bike heavily dominates the flat 10 km lake sections, the false-flat rollers, and the high-speed descents down from Goldingen.

Comparison between the Triathlon and Road setup for different groups, as presented by the Swiss Side Performance Platform, showing that the Road setup is only faster on the steepest climbs.

Comparison between the Triathlon and Road setup for the first loop of the course, as presented by the Swiss Side Performance Platform, showing that the Road setup is only faster on the steepest climbs, shown by the reduction in the time deficit curve circled in red above.

The Perfect Pacing Strategy: Managing the Swiss Rollercoaster

Riding Rapperswil at a constant power output is not optimal. Instead, you should use your energy more wisely. Using our platform’s Auto-Grouping feature, we divided the 30 segments of the course into intelligent, memorable groups and optimized for a pacing strategy that maximizes speed for the provided power budget of 220 W normalized. The result is a pacing strategy where you have to push more on the climbs and conserve energy on the descents.

The key principle is to maximize power where speed is low (climbs) and conserve power where speed is high (descents and flats), using the physics of aerodynamic drag and gravity to your advantage.

• On Witches' Hill & Goldingen Climbs: Push. The simulation engine recommends a tactical over-pacing strategy of +26 W to +36 W above your target reference power on the climbs and steep climbs. Because your speed drops significantly on these sections, gravity becomes the dominant resistance, making power output your absolute highest priority.

• On the High-Speed Descents: Recover. Pushing high watts while flying down toward Ermenswil yields diminishing returns due to exponential aerodynamic drag. The platform advises a controlled under-pacing strategy of -68 W (or coasting / not-pedalling if you exceed your maximum gear ratio).

• Along the Obersee Flats: Hold steady. Lock into your aerobars and maintain a power below your normalized power target (-15 W). The focus here is entirely on minimizing your frontal area to slice through the localized lake winds. If you experience tailwind, you can reduce you power output further (-28 W).

The Bottom Line: By deploying your energy where the physics demands it, the optimized pacing strategy brings our simulated rider to T2, 2 minutes and 18 seconds faster than a flat, constant power strategy, for the same physiological effort.

The optimal pacing strategy for the simulated rider setup, as presented by the Swiss Side Performance Platform.

Comparison between a constant power strategy and the optimized pacing strategy, as presented by the Swiss Side Performance Platform.

Get Your Personal Race-Day Blueprint

If you want to know about the pacing and equipment choice for your personal profile and setup, try the Swiss Side Performance Platform.

You can test the platform for 10 days by starting a free trial of our PRO plan. Crucially, you do not have to provide any payment information and there is no automatic subscription at the end of the trial.

Stop relying on simplified rules of thumb or race-day guesswork. Input your specific weight, bike setup, and your power target to generate a customized, scientifically proven map to your next PR.

Learn more about the Swiss Side Performance Platform and start your unbinding free trial.

If you want to learn more about the Performance Platform and the pacing and equipment choice for IM Rapperswil, you can join us at the Swiss Side Performance Night at Temposport in Horgen on June 3, 2026.