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Race IntelligenceLes Sables d'Olonne, France

IRONMAN Les Sables d'Olonne-Vendee

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
27 June 2027
Swim
3.8 km
Bike
180 km
Run
42.2 km

Published route evidence. Final 2027 route pending. Checked 15 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 Les Sables d'Olonne-Vendee actually gives you

You swim 3.8 km along the open Atlantic coast from the Grande Plage into the mythical Vendée Globe Channel, ride a rolling, demanding 180 km through 17 Vendée municipalities with several successive restarts, then run four loops from the harbour along the beach, past Lac de Tanchet and Puits d'Enfer to a festive finish at Place du Palais de Justice. The ocean swim and the bike's repeated restarts are what separate this course from a flatter, more sheltered full-distance day.

Show distances in

Swim

3.8 km

Open Atlantic Coast

Setting
the Grande Plage, finishing at the Vendée Globe Channel

An open Atlantic-coast swim from the Grande Plage into the Vendée Globe Channel carries genuine ocean exposure, unlike a sheltered lake or river start.

Source: 2027 current route

Bike

180 km

Rolling, Demanding Countryside With Several Restarts

Setting
17 municipalities of the Vendée, starting on the Remblai of Les Sables d'Olonne

A rolling, demanding 180 km through 17 municipalities with several successive restarts asks for restraint at every restart, not just at the start.

Source: 2025 file, current course page

Run

42.2 km

Harbour, Beach and Lakeside, Four Loops

Layout
4 loops
Setting
the harbour, the Grande Plage sand, the Remblai, Lac de Tanchet and Puits d'Enfer, finishing at Place du Palais de Justice

A four-loop course through the harbour, along the beach and past two lakes gives constant scenery and constant pacing feedback across the marathon.

Source: 2027 current route
Where these course facts come from

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

Respect the open Atlantic

  1. 0–3800 m

    From the Grande Plage to the Channel

    Treat the open coast with real respect

    This is an open Atlantic-coast swim, not a sheltered lake or river. Settle into a controlled rhythm early and sight deliberately, since conditions here can be genuinely rougher than a protected venue.

    • Settle by 400 m
    • Sight more frequently than you would in calm water

Bike

Ride every restart the same way

  1. 0 km–60 km

    Out from the Remblai

    Ride the first restarts to a number

    The course opens on the famous Remblai before heading into a rolling, demanding route with several successive restarts. Cap your effort at each one rather than treating it as a fresh start.

    • Cap power at every restart
    • Fuel early, before the terrain gets demanding

  2. 60 km–130 km

    Through the Vendée's 17 municipalities

    Hold one number through the rolling middle

    The organiser's own description calls this course demanding with successive restarts; the temptation is to spike effort at each one. Hold your planned power through the whole rolling middle section instead.

    • Ride to power, not to each restart's fresh feeling
    • Stay on the fuelling schedule

  3. 130 km–180 km

    Back towards Les Sables d'Olonne

    Arrive at T2 ready for a four-loop marathon

    As the course returns towards the coast, shift focus to the run. Finish planned nutrition and let cadence rise before the transition.

    • Finish the planned bottle
    • Let cadence rise before T2

Run

Use four loops as four honest checks

  1. 0 km–10.55 km

    Loop one: harbour and beach

    Convert bike legs before racing

    The run opens along the harbour to the green lighthouse, then a stretch on the Grande Plage sand before the main loop begins. Use this to settle, especially on the sand.

    • Shorten stride on the sand
    • Let the opening kilometre feel easy

  2. 10.55 km–21.1 km

    Loop two: Remblai, Lac de Tanchet, Puits d'Enfer

    Use the repeat as an honest check

    Passing the same lakes and landmarks a second time gives a clear read on how loop one's pace is holding. Adjust deliberately rather than waiting until the legs force the issue.

    • Compare loop two to loop one
    • Keep fuelling on schedule

  3. 21.1 km–31.65 km

    Loop three

    Protect the pace that's still working

    The third loop is where a demanding bike and an open-water swim start to show up in the legs. Manage effort rather than chasing a pace that's slipping.

    • Reassess goal pace honestly
    • Keep taking aid on schedule

  4. 31.65 km–42.2 km

    Loop four to Place du Palais de Justice

    Spend what three honest loops left you

    The final loop finishes at Place du Palais de Justice for what the organiser calls a festive finish. If the day has gone to plan, decide deliberately whether to push.

    • Decide the finish honestly
    • Save something for the finish square

04 Race week

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
16.3–25.3°CDew point centred on 14.7°C
Wind and gusts
15.0 km/hGusts up to 42.8 km/hPrevailing direction WNW
Rain likelihood
Up to 85%Wet-surface uncertainty retained

Historical baseline, 2019–2025 · Open-Meteo historical archive · Updated 2026-09-15.Historical comparison only. This is not a forecast for 2027.

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 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 full distance 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 full distance 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 Les Sables d'Olonne-Vendee 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 routeFull-distance training plansTraining plans for the 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

ArticleFull-distance race strategy: calm execution beats chaosThe pacing discipline a demanding, restart-heavy bike course asks for.ArticleFix the first ten minutes off the bikeUseful before a four-loop run that starts on legs that rode a demanding bike.

Evidence

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 2026-09-15.