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Race IntelligenceVersailles, France

IRONMAN 70.3 Versailles

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
11 October 2026
Swim
1.9 km
Bike
90 km
Run
21.1 km

Published route evidence. Final 2026 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.

01 Race Card

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.

02 The course

What Versailles actually gives you

You swim a calm, fully enclosed lake at the foot of the Château de Versailles, then take on a rolling 90 km loop through the Chevreuse Valley with two named climbs to respect. The run brings you back past the château and through the Potager du Roi and Versailles' historic streets, including a cobblestone finish. The bike decides how well you get to enjoy the history on the run.

Show distances in

Swim

1.9 km

Lake / Calm Water

Layout
1 loop
Setting
Pièce d'Eau des Suisses, at the foot of the Château de Versailles

A fully enclosed ornamental lake removes chop and current from the equation almost entirely.

Source: 2026 course description

Bike

90 km

Rolling Valley Roads

Layout
1 loop
Setting
Chevreuse Valley, past the Abbaye des Vaux de Cernay

Two named, graded climbs (Côte de la Vacheresse and the 17 Tournants) are real, documented elevation cost the model needs to respect even without a published course total.

Source: 2026 published map

Run

21.1 km

Historic Parkland and City Streets

Layout
3.5 loops
Setting
Pièce d'Eau des Suisses, the Potager du Roi and Versailles' historic centre

An unpaved path section and a cobblestone stretch near the finish add real technicality a flat road course wouldn't have.

Source: 2026 published map
Where these course facts come from

These facts come from the organiser’s latest published material: swim, 2026 course description; bike, 2026 published map; run, 2026 published map. They describe the character of the course. They do not confirm the final 2026 route.

03 Race plan

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 calm water

  1. 0–300 m

    The start

    A calm lake rewards a calm start

    The Pièce d'Eau des Suisses is fully enclosed with no chop or current to fight. Use that calm to settle into your own rhythm early rather than matching whoever is next to you.

    • Sight early, settle into rhythm
    • Let the field spread before you commit to pace

Bike

Ride the named climbs, don't race them

  1. 0 km–30 km

    Into the valley

    Get organised before the climbs arrive

    The course heads out from Versailles towards Gif-sur-Yvette and Les Molières before the terrain properly changes. Use this stretch to settle in and start fuelling before the Chevreuse Valley's climbs ask anything of you.

    • Start drinking before the terrain changes
    • Check effort before speed

  2. 30 km–55 km

    The named climbs

    Ride the Côte de la Vacheresse and the 17 Tournants by effort

    These two graded climbs (1.6 km at 4.6%, then 1.3 km at 5.7%) are the real elevation cost of this course. A hard effort on either one is repaid on the run, not on the clock.

    • Shift early on both climbs
    • Use the descents to recover, not attack

    A strong climb here is not free speed later

  3. 55 km–90 km

    Return to Versailles

    Bring a run back into the château grounds

    As the course returns through Saint-Forget and Guyancourt towards Versailles, stop asking the legs for proof. Finish your planned nutrition and arrive at T2 ready to run through the history that's waiting.

    • Finish the bottle you planned
    • Let cadence rise before T2

Run

Run the history, not just the distance

  1. 0 km–7 km

    Past the château

    Let the lake settle your legs

    The first loop takes you along the Pièce d'Eau des Suisses and through the Potager du Roi. Use the scenery and the unpaved path section to turn bike legs into running legs before committing to pace.

    • Shorten your stride on the unpaved section
    • Take the first aid station deliberately

  2. 7 km–16 km

    Use the repeats

    Let the loops check you, not excite you

    The 3.5-loop course brings you past the same landmarks, including the cobblestones near École Spéciale d'Architecture, several times. Use each pass to check posture, footing and fuelling rather than racing the crowd near the finish early.

    • Shorten your stride over the cobblestones
    • Assign a check to each landmark

    The finish line you pass isn't yours until the last loop

  3. 16 km–21.1 km

    Decide

    Earn the last move through the château grounds

    Only on the final loop should you decide whether the day has given you permission to race. If it has, change one thing at a time: cadence, then posture, then pace.

    • Look for three good kilometres
    • Keep the finish decision yours

04 Race week

What I would keep an eye on

There is no useful 2026 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
8.0–17.6°CDew point centred on 9.6°C
Wind and gusts
11.6 km/hGusts up to 47.9 km/hPrevailing direction 234°
Rain likelihood
Up to 85%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 2026.

05 Method

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 2026 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.

06 Next steps

If Versailles is your race

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

The work from here.

Self-guided routeHalf-distance training plansTraining plans for the fitness and durability this course asks for.See the plans Personalised routeWork with me on the whole buildCoaching when you want the plan, feedback and race decisions joined up.See coaching

Further reading

ArticleHow to pace a 70.3 so you can still runThe longer version of the swim-bike-run pacing logic behind this Race Card.ArticleFix the first ten minutes off the bikeUseful before a run that immediately asks for technical footing on tired legs.

Evidence

Sources and verification

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