The Thun Marathon: Flat on Paper, Tricky Underfoot

The Course: Three Laps Through the Heart of Thun

The run measures 42.4 km over three laps around the lake and through the city center: lakefront, event zone, Schadaupark, the Scherzligschleuse bridge, with a pass through the local athletics track on every lap. Total elevation gain is just 22 m, with a single small climb in town. On paper, a PR marathon.

The reality is more nuanced. The surface is mixed: asphalt, but also plenty of gravel and cobbles. After 180 km on the bike with 2,000-plus meters of climbing, footing on uneven ground becomes a real factor, especially on the last two laps when your run form breaks down.

Shoes: The Decision to Make Now

Pick shoes you've tested on uneven surfaces. Super shoes with a very stiff plate and a high stack perform best on smooth asphalt; on cobbles and gravel they can get unstable when you're fatigued. That doesn't mean they're the wrong choice, but you need to test them on a similar surface in training, under fatigue, before deciding. If you can't test, a fast but stable shoe is the safer bet.

Heat and Aid Stations: Three Passes, One Plan

The three-lap format has one huge advantage: you pass the same aid stations multiple times and can plan precisely. The aid stations are well stocked: ice, cold showers, Coke, broth. With average highs of 27 °C and a history of serious heat (peaks of 36 °C on the bike in 2023), cooling matters: ice in your tri suit and cold showers every lap if temperatures climb.

A concrete warning: one race report mentions GI cramps from overdoing it at the aid stations. Three laps mean lots of passes and lots of temptation. Don't treat the aid stations like a buffet: decide beforehand what you'll take and where, and limit experiments — especially with the broth, if you've never used it in a race.

Pacing Over Three Laps

The lap structure helps mentally but lies about pace. Simple scheme:

• Lap 1: deliberately controlled. If the pace feels easy, it's the right one. Run the small climb in town with short, light steps — don't attack it.
• Lap 2: the lap of truth. Hold your pace and check how you respond on gravel and cobbles: if your footing starts getting sloppy, shorten your stride.
• Lap 3: this is where you cash in what you saved. The crowds in the center and the pass through the track help.

As a rough reference (estimates, not official data): a happy finisher closes the marathon around 5:00, a mid-pack goal sits around 4:20, a fast athlete around 3:45.

What to Do in Training

Three concrete actions:

1. Include at least two long runs on mixed surfaces (asphalt + gravel + pavé or cobbles if available) in the shoes you'll race in. 2. Test your heat protocol in training: ice, water over your body, adjusted pace. Don't improvise it on race day. 3. Write out your aid station plan per lap: what you take, what you skip. Memorize it.

The Thun marathon rewards those who arrive with well-managed legs off the bike and who don't get caught out by the surface or the aid stations. The flat course gives you the rest for free.