The Bike Course in Thun: 180 km, Two Laps and Two Real Climbs Per Lap

The course in a nutshell

Two laps totaling between 178.8 and 180.2 km, heading toward Spiez, the Gurbe valley, Bern airport and the Gantrisch area. The official elevation gain is 2,050 m, but several race reports cite roughly 2,200 m: prepare your legs for the worst-case scenario, not the one on paper.

The structure of each lap is clear:

• A rolling first section, with short punchy climbs that break your rhythm.
• After the turnaround, two significant climbs at 4-5%, each a 20-25 minute effort.
• Very fast descents, including a mandatory no-aero zone on one descent.
• The last ~8 km of each lap are all downhill back to Thun.

Pacing: where you win and where you lose

Four 20-25 minute efforts at 4-5% over the whole race: that's the real demand of this course. These aren't walls, they're tempo climbs. The classic mistake is going too hard on the first lap and paying for it on the second, when in 2023 some sections hit peaks of 36 °C.

Practical rules:

• Set a power cap (or an RPE cap) for the climbs and stick to it on the first lap, when you're feeling good.
• Don't try to make up time on the descents that you lack on the climbs: the descents are lightning fast and one bans the aero position. The risk isn't worth the seconds.
• On the short punchy climbs in the first section, stay seated and spin where you can: they're lots of small withdrawals from your energy bank.

Gearing and setup

You need proper gearing: on 4-5% grades for 20-25 minutes you want to pedal at a high cadence without going over threshold. If your current combination forces you into low cadences on climbs like these in training, change it before the race, not during.

On the no-aero zone: respect the signage and check the rules in the athlete guide. Anyone not comfortable descending on a TT bike should explicitly work on it in their build.

Heat: the second lap is a different race

You start fresh from the lake (average water temp 17 °C), but in the middle of the day the heat can climb: average air high of 27 °C, with peaks up to 36 °C on some sections in 2023. The second lap lands right there. Plan your hydration and salt for the hot scenario and use the final ~8 downhill km of each lap to eat, drink and bring your heart rate down before returning to the event zone — and, on the second pass, before the marathon.

What to do in training

The most specific test you can do: in a single long ride, simulate two 20-25 minute blocks at 4-5% at race effort, spaced as they are on race day, and see how your legs respond at the end. Repeat it in hot conditions at least once. If the second block falls apart, your race-day power cap is too high: lower it and retest.

A second useful session: long descents at race speed, with smooth position changes (aero / no-aero) and controlled braking. In Thun there's a lot of descending, and the time goes to whoever descends clean, not whoever takes risks.

The decision to make

Before leaving for Switzerland you need to have decided three things: your gearing, your effort cap on the climbs and your hydration plan for the 36 °C scenario. If any of those three answers is "I'll figure it out on race day," you're not ready for this course.