HOKA UTMB Mont-Blanc
TDS (Sur les Traces des Ducs de Savoie)
Courmayeur → Chamonix
Race guide
Updated 19 July 2026
The TDS – Sur les Traces des Ducs de Savoie – is one of the most demanding races in the UTMB Mont-Blanc festival, covering 148 km and 8908 m of climbing from Courmayeur in Italy to the finish line in Chamonix, France. Running point-to-point through the Savoie Alps, it traces historic trade and pilgrimage routes used by the Dukes of Savoy, crossing into France early and threading through remote valleys and high cols before rejoining the classic UTMB finishing corridor through Les Houches. With a high point of 2597 m and relentless rolling terrain throughout its middle third, the TDS is not a race that lets you recover. Every flat section is short-lived; the climbs stack up methodically across two days and a night, and the cut-offs are tight enough to demand consistent, disciplined moving from the gun.
Course & Terrain Overview
The route leaves Courmayeur at 1222 m and immediately climbs toward Lac Combal at 1980 m, reaching it within 15 km – the first cut-off checkpoint at Wednesday 04:00. The terrain here is broad, grassy valley floor giving way to rocky moraine, and it sets the tone: runnable in places, technical in others. From Col Chavannes / Alpetta at 2316 m and 22 km, a long descent drops runners nearly 1500 m into Bourg-Saint-Maurice at 805 m and 50 km, the lowest point on the course and the first crew access after the start. The middle section from Bourg-Saint-Maurice through Cormet de Roselend (1985 m, 67 km) to Beaufort (1246 m, 89 km) is the heart of the race: sustained climbs on open alpine pasture, exposed ridgelines and grassy double-track descents with limited shade. This is where many runners lose time relative to the cut-offs without realising it. From Beaufort, the route climbs again through Hauteluce (1115 m, 100 km) to Col du Joly at 1927 m and 109 km – a long, grinding ascent arriving in the early hours of Thursday morning. The final third into Les Contamines (1184 m, 120 km) and through to Les Houches (1063 m, 139 km) is comparatively gentler but comes on heavily fatigued legs late in the race.
Decisive Climbs & Where the Race Is Won or Lost
Three sections define how your TDS unfolds. The first is the early climb to Col Chavannes / Alpetta at 2316 m – arriving here quickly and smoothly, without burning matches, is critical before the long descent to Bourg-Saint-Maurice. The second is Cormet de Roselend. Arriving at km 67 and cut-off 15:30 Wednesday, this climb represents the mid-race stress test: your legs already have 50+ km on them, and the ascent from Bourg-Saint-Maurice gains over 1100 m of vertical. Runners who go too hard on the descent into Bourg-Saint-Maurice consistently pay for it here. The third and most psychologically brutal section is the climb to Col du Joly at 109 km, reached at the cut-off of Thursday 03:00. Coming deep in the night, after almost 24 hours of racing for mid-pack runners, the 800 m of ascent from Hauteluce to the col is where DNFs accumulate. Arriving at Col du Joly with any meaningful buffer is the clearest indicator that you will finish. The run from Les Houches to Chamonix in the final 9 km, while flat and well-tracked, should not be underestimated in terms of time – the 12:30 Thursday cut-off at Les Houches gives approximately 7.5 hours to cover the last 9 km to the 20:00 finish cut-off, which is generous, but fatigue-driven shuffling is real.
Pacing & Cut-Off Strategy
The cut-off structure tells you exactly what pace the race demands. From the start in Courmayeur to Bourg-Saint-Maurice (50 km) you have until Wednesday 11:00, meaning a Wednesday night start gives roughly 11 hours for the first 50 km – do not interpret this as comfortable. The Cormet de Roselend cut-off (67 km, 15:30 Wednesday) is only 4.5 hours after Bourg-Saint-Maurice for 17 km and 1180 m of climbing: that is a demanding ask and requires leaving Bourg-Saint-Maurice promptly without lingering at the crew point. Target arriving at each checkpoint with at least 30–45 minutes of buffer; the terrain and any weather deterioration will eat that margin faster than you expect. Beaufort at 89 km has a cut-off of 21:00 Wednesday – use the 4-hour gap between Beaufort and Hauteluce's 00:30 Thursday cut-off to eat a proper meal at Beaufort, rest your feet, and prepare mentally for the night section ahead. The Col du Joly cut-off (03:00 Thursday) is the race's de facto filter: if you leave Les Contamines by 06:30 Thursday with any running left in your legs, the finish in Chamonix at 20:00 is achievable.
Fuelling & Crew Access
Crew can access the race at five points: Courmayeur (start), Bourg-Saint-Maurice (50 km), Beaufort (89 km), Les Contamines (120 km), Les Houches (139 km), and the finish in Chamonix. Plan your crew strategy around the two most important stops: Bourg-Saint-Maurice and Beaufort. At Bourg-Saint-Maurice, you will have been running for 50 km with 1600+ m of climbing completed – prioritise real food, a sock change and a kit check, especially if conditions have turned wet. Beaufort at 89 km is the final crew point before the long night section: this is where you load up on calories, add layers if needed and prepare your headtorch kit. Between Les Contamines and Les Houches there is no crew access for 19 km, and this section arrives very late in the race with exhausted runners. Aim to take on 200–250 kcal per hour throughout the race and increase sodium intake during the warm afternoon sections between Bourg-Saint-Maurice and Beaufort. Hydration points at each named checkpoint reduce the need to carry large water volumes, but the exposed high sections – particularly around Cormet de Roselend and Col du Joly – can be remote enough that carrying 1.5 litres is prudent in warm conditions.
Conditions to Expect
The TDS runs in late August as part of the UTMB Mont-Blanc week. Expect warm to hot conditions through the daytime sections – particularly the descent into Bourg-Saint-Maurice, which can sit well above 20°C in the valley. The high cols, especially Col Chavannes / Alpetta at 2316 m and the high point of 2597 m, can be dramatically cooler and susceptible to afternoon thunderstorms; mandatory kit requirements exist for good reason on this course. The night section between Beaufort and Les Contamines crosses Col du Joly at around 2000 m in the early hours, where temperatures can drop to near zero even in August. Bring a windproof and a mid-layer that you can access quickly without stopping. Footing becomes significantly more technical on rocky descents in the dark; poles are used by the vast majority of finishers and are strongly recommended for the climb to Cormet de Roselend and the long descent into the Contamines valley. Trail conditions vary year to year but grassy slopes can be slippery after afternoon rain, particularly on the steeper pitches above Hauteluce.
Race TDS (Sur les Traces des Ducs de Savoie) with Crux
Get the strategy, fuelling and crew plan dialled for this exact course — built from the real route, climbs and cut-offs. Your first race is free.
Plan this race — freeCourse profile
Checkpoints & cut-offs
✓ Course data verified against the official source (2026-07-05) · official source
0 km · 1221 m · —
7.6 km · 1953 m · —
16.4 km · 1981 m · Tue 03:30
36.5 km · 2188 m · Tue 08:30
50.8 km · 836 m · Tue 11:00
65.9 km · 1966 m · Tue 17:15
73.5 km · 1646 m · Tue 19:30
92.3 km · 746 m · Wed 03:00
98.8 km · 1174 m · Wed 05:30
115.6 km · 1869 m · Wed 11:15
123.3 km · 1136 m · Wed 13:15
142 km · 1007 m · Wed 19:15
151.2 km · 1043 m · Wed 20:45
More races
More UTMB World Series Finals
Similar distance (100 miles and beyond)
Racing TDS (Sur les Traces des Ducs de Savoie)?
Get a complete race strategy — pacing, fuelling, crew plan and the crux moments — built on this exact course.
Plan your race in Crux →Strava is your training. Crux is your races.