INFERNO Triathlon Training Plan & Preparation

Course & Elevation

The road bike leg of the Inferno Triathlon covers 97 km point to point from Oberhofen on Lake Thun to Grindelwald, straight through the Bernese Oberland. It belongs to an event the organizer counts among the hardest triathlons in the world, with roughly 5,500 metres of climbing across all disciplines combined.

The first test arrives after barely three kilometres: the climb via Sigriswil up to Beatenberg, close to eight kilometres at an average of 7.1 percent for 554 metres of gain. The course then grants a long breathing space, rolling largely flat through Interlaken and along the valley to Meiringen. A good third of the total distance is level ground, the place to make speed and to eat.

The finale makes up for it. From km 65.7 the ascent to Grosse Scheidegg begins, delivered in two instalments: first nearly nine kilometres at 7.8 percent gaining 696 metres, then, after a brief respite, another 7.5 km at 8.3 percent and 621 metres of gain to the top of the pass. From there the road drops to Grindelwald, where the mountain bike takes over. In total this leg accumulates around 2,200 metres of climbing.

Pacing Strategy

A 7.8 km climb at 7 percent arrives in the very first twelfth – with cold, fresh legs the urge to overdo it is strong, so ride it controlled and aerobic. The long valley section from kilometre 12 to 65 is flat to rolling: clean aero position and steady power matter here, not attacks. The leg is decided on the two linked closing climbs from kilometre 66 (8.9 km at 7.8 percent) and kilometre 76 (7.5 km at 8.3 percent), which together lift you more than 1,300 metres to the high point.

Because a mountain-bike split and the run to the Schilthorn still follow, ride the mountains sustainably below threshold rather than at your limit. The main trap is forcing the early climb or the valley and arriving empty at the closing mountains.

12-Week Preparation

Plan on roughly four to five and a half hours for the 97 km and its 2,200 metres of climbing as an age-group athlete, bearing in mind this is the middle of a very long day, after the swim and before the mountain bike and the mountain run.

The demands split cleanly in two. The early climb to Beatenberg and above all the two-step final ascent to Grosse Scheidegg require 40 to 70 minutes of steady, continuous climbing, while the long flat middle section between Interlaken and Meiringen feels closer to a solo time trial. The decisive skill is power management on Grosse Scheidegg: 1,300 metres of gain in two instalments at the end of the leg, with the knowledge that two more disciplines and more mountains follow. Ride above your means here and the Schilthorn will collect the debt with interest.

Your training should therefore feature long rides with the climbing loaded into the back half, ideally including sustained ascents of 600 to 700 metres at constant, controlled power. Add flat sessions at steady brisk pace in an aerodynamic position for the valley section. The descent to Grindelwald deserves practice too; confident descending buys time at zero energy cost. And because this leg never happens in isolation, brick sessions belong in the plan: bike workouts followed immediately by further effort, so your body knows how to keep working after dismounting.