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Race IntelligenceRapperswil-Jona, Switzerland

IRONMAN 70.3 Switzerland

Know your day before you race it.

Enter four numbers you already train with. You get a likely finish range, target paces and watts, and how I would race this course.

Race day
6 June 2027
Swim
1.9 km
Bike
90 km
Run
21.1 km

Published route evidence. Final 2027 route pending. Checked 13 Sept 2026.

Official course routeThe real GPS route for each discipline with official GPX data available, drawn in one shared coordinate space.

Build my Race Card

Your first range uses conservative assumptions. Add optional evidence to make it more specific. It is calculated in your browser and saved only on this device.

Your numbers
Distance unit
Weight unit
You and this race
Sharpen your range with more detailOptional. Recent swim, bike and run results, equipment and transitions.

Add only the evidence you have. Every control changes a discipline range, its uncertainty, or an execution-risk explanation.

Swim evidence

Replaces the broad pool-to-open-water assumption.

Bike and equipment

These replace broad mass, aerodynamics, tyre, and power-to-speed assumptions.

Run evidence

A recent effort and honest durability/acclimation answers refine the post-bike run.

Race execution

Transition proficiency changes the T1/T2 range and how wet conditions are treated.

What Switzerland actually gives you

You swim a clear, calm loop in the Obersee, ride two hilly loops through the countryside around Rapperswil-Jona with demanding climbs and rewarding descents, then run through medieval streets and the lakeside Strandweg before the course's own named 'stairway to heaven' climb to the finish. This is a course that punishes anyone who treats the first bike loop as separate from the second.

Show distances in

Swim

1.9 km

Clear Alpine Lake Loop

Setting
Obersee, Rapperswil-Jona

A clear, calm Obersee loop gives a controlled start before the demanding bike ahead.

Source: 2025 previous-edition route

Bike

90 km

Hilly Roads With Demanding Climbs

Layout
2 loops
Setting
the countryside around Rapperswil-Jona

Two hilly loops with demanding climbs mean the first lap's effort decides how much the second lap and the run actually have left.

Source: 2025 previous-edition route

Run

21.1 km

Medieval Streets, Lakeside Path and a Stepped Climb

Setting
Rapperswil-Jona's old town, Strandweg lakeside and the 'stairway to heaven'

Medieval streets, the Strandweg lakeside and a named stepped climb reward legs that didn't spend everything on the bike's first loop.

Source: 2025 previous-edition route
Where these course facts come from

These facts come from the organiser’s latest published material: swim, 2025 previous-edition route; bike, 2025 previous-edition route; run, 2025 previous-edition route. They describe the character of the course. They do not confirm the final 2027 route.

How I’d want you to race it

One job for each part of this course. The distance markers tell you when the job changes. The course tells you why.

Swim

Use the alpine lake

  1. 0–300 m

    The start

    Settle into the Obersee

    The clear, calm lake gives a controlled start before the demanding bike ahead.

    • Seed honestly
    • Settle into rhythm

Bike

Ride both loops the same

  1. 0 km45 km

    First loop

    Cap the climbs

    Ride the demanding climbs to a power cap. You will see this terrain again on lap two.

    • Cap power on the climbs
    • Fuel early
  2. 45 km90 km

    Second loop

    Match your first loop

    Hold the same effort on the repeat climbs and finish your nutrition before the run.

    • Stay patient
    • Finish planned nutrition

Run

Save something for the stairway

  1. 0 km10.5 km

    Old town and lakeside

    Start controlled

    Let the medieval streets and Strandweg lakeside feel easy before the course's own named climb.

    • Easy first aid station
    • Check posture
  2. 10.5 km21.1 km

    The stairway to heaven

    Save something for the stairs

    The named stepped climb near the finish rewards legs that didn't spend everything on the bike's climbs.

    • Shorten your stride on the steps
    • Choose the last move late

What I would keep an eye on

There is no useful 2027 forecast this far out. For now, past race dates give us a point of reference. Closer to the race, the forecast will tell us whether the plan needs changing.

Forecast statusToo early for a forecast

A race-day forecast is not meaningful yet; check back closer to the event.

Temperature
12.1–23.8°CDew point centred on 12.3°C
Wind and gusts
5.0 km/hGusts up to 29.2 km/hPrevailing direction NNW
Rain likelihood
Up to 100%Wet-surface uncertainty retained

Historical baseline, 2019–2025 · Open-Meteo historical archive · Updated 2026-09-13.Historical comparison only. This is not a forecast for 2027.

What goes into your range

Your CSS, FTP, weight and run threshold create the first range. Open-water, bike, run and execution evidence can replace broad assumptions. Course data and the historical conditions baseline shape every simulation.

  1. Your numbersCSS · FTP · weight · run threshold
  2. This raceDistance · water type · elevation · exposure
  3. Your Race CardFinish and discipline ranges, with target paces and watts

Confidence is built from four inputs

Athlete evidence
Builds with recent open-water, bike and run efforts
Bike setup
Builds with equipment, mass, aero and tyre detail
Course evidence
Partial while the 2027 route is unconfirmed
Race-week conditions
Historical baseline until a forecast is useful
How the model works

It starts with the targets in your Race Card, then samples the parts of a 70.3 that vary: open-water pace, transitions, bike speed at the planned power, and the drop in run performance after the swim and bike. Repeating that calculation produces a likely range rather than a single heroic number.

The current time calculation uses this race’s published distances, or standard 70.3 distances where none are published, with the available course headings, elevation and exposure evidence. Weather scenarios vary temperature, dew point, wind, gusts, rain and water conditions together. Unknown route detail stays visible as uncertainty rather than false precision.

It is not predicting your exact finishing time, placing, or race-day weather. It answers a narrower question: given the plan and the information we have, what range of day is plausible, and where is the uncertainty coming from?

Confidence is not a permanent “low”. It is recalculated across four separate inputs:

  • Your evidence: consistent inputs and recent race-like swim, bike, and run results.
  • Bike setup: measured or specified aerodynamics rather than a broad prior.
  • The course: verified distance and route character, including elevation and technical sections.
  • The conditions: a current forecast is more useful than a historical comparison.

It starts low when those inputs are broad. It can become moderate or high as the evidence improves. A narrower range means better information, not a guarantee.

If Switzerland is your race

Your range is built on today’s numbers. The months of training before race day decide what those numbers become.

Sources and verification

Course status: Partially verified. The organiser’s descriptions and latest published route profiles are in use. The final 2027 route is not yet confirmed. Last checked 2026-09-13.