The Bike at Les Sables-d'Olonne: 180 km Over Two Laps, With the Wind as Your Opponent

The Big Picture

The full-distance bike leg is 180 km over two laps. A race-dedicated source describes it as a rolling, undulating course with no real climbs but never truly flat. There's no reliable figure for the full's total elevation gain: our race sheet lists roughly 500 m of climbing, but that number isn't confirmed in the sources. For comparison, the 70.3 held on the same terrain is described as having about 600 m of gain over 90 km. If the full follows those profiles, the actual elevation could exceed the 500 m listed. Sources differ: plan for a scenario between 500 and 1,000 m of climbing and check the official 2027 map as soon as it's published.

The Terrain

The 70.3 course crosses the Olonne forest, the salt marshes, and the villages of the Vendée countryside, with the start and finish near the sea. Course details for the full aren't published in the sources, but the terrain is the same: country roads, false flats, few visual landmarks, and wind coming off the Atlantic with nothing to block it. In 2025 athlete surveys, the bike leg ranked among the best in the IRONMAN Series for overall experience: a sign of good roads and a fast-flowing course, not an easy one.

The Real Opponent: The Wind

In late June on the Atlantic coast, wind is the most likely variable. On a two-lap course that means one thing: you'll ride the headwind sections twice, and the second lap comes after 90 km in your legs. Plenty of coastal courses teach the same lesson: riders who push into the headwind to hold their speed pay for all of it on the marathon. Ride by power or perceived effort, not by speed. With a tailwind, pick it up gently; into a headwind, accept the slower speed and hold your aero position.

Pacing: The Second Lap Decides the Marathon

The practical advice is simple: first lap at 70-72% of your FTP, no exceptions. On a rolling course, the temptation is to surge on every false flat: every spike above threshold is a loan the marathon will make you repay with interest. If you reach the halfway point feeling like you've done too little, you're exactly where you should be. On the second lap you can lift the effort slightly, but only if your legs and nutrition are holding up.

Equipment and Gearing

With 500-1,000 m of climbing over 180 km you don't need climbing gears: a standard TT chainring with an 11-30 or 11-32 cassette covers everything and keeps your cadence up on headwind false flats. Wheels: with possible Atlantic wind, a mid-depth rim (50-60 mm) up front is easier to handle than a disc wheel exposed to crosswind gusts; decide based on the week's forecast. Train your aerobars and aero position: on this course you'll spend many hours down in the bars.

What to Do Now

Three concrete actions. First: build 60-90 minute race-pace blocks into your long rides on rolling terrain, ideally windy, with power capped at 70-72% FTP. Second: test your race nutrition (80-90 g/h of carbs) on those same long rides, not on paper. Third: when the official 2027 map comes out, download the route file, check the actual elevation gain, and update your wheel choice based on the wind forecast. The bike at Les Sables-d'Olonne doesn't break your legs with climbs: it wears you down with relentlessness. The disciplined rider wins over 180 km.