# Race the Mont-Blanc Marathon Route: Chamonix Trail Running Guide
Chamonix is the most internationally significant trail-running town in the world. No other valley combines this quality of trail surface, this concentration of vertical, this density of lift-served access, and this depth of trail-running culture — Marathon du Mont-Blanc, UTMB, and a year-round community of runners who treat technical mountain terrain as their primary training environment.
Whether you are training for the Marathon du Mont-Blanc itself, building toward UTMB, or planning a trail-running trip that combines world-class technical terrain with a town that knows how to host runners, here is how to run Chamonix like a local.
The Five Foundational Routes
Every serious Chamonix trail runner returns to the same five core trail systems. Learn these, and you have learned 80 percent of what makes this valley great.
Le Grand Balcon Sud **18km loop, 1,200m elevation gain — moderate technical**
The signature run of the Chamonix valley. From Plan Praz (accessible by the Brévent cable car from town, 1,000m of elevation eliminated) the trail traces the balcon south at approximately 2,000m altitude, traversing beneath the Aiguilles Rouges and providing a continuous view of the entire Mont Blanc massif across the valley. Connects Plan Praz to La Flégère and onward to Argentière, where you can descend to take the lift or train back to Chamonix.
This trail is the foundation of the Marathon du Mont-Blanc course. Several sections of the 90K, the Marathon, and the 23K traverse this exact route. Running it puts you on the same surface that elite athletes race.
Le Grand Balcon Nord **16km loop, 950m elevation gain — moderate technical**
The Grand Balcon Sud's quieter twin, traversing the north side of the valley at the foot of the Mont Blanc massif itself. The path runs beneath the Drus and the Aiguille du Midi at approximately 2,000m, providing the kind of close-up Mont Blanc views that the Aiguille du Midi cable car normally costs €72 to provide. Access from the Plan de l'Aiguille (mid-station of the Aiguille du Midi cable car). Less trafficked than the Sud balcon. Trail surface marginally more technical.
Brévent Vertical **7km out-and-back, 1,490m elevation gain — strenuous**
This is the vertical kilometer training route. From Chamonix town centre (1,035m), follow the marked trail through the Bois du Bouchet and then up the steep wooded north flank of the Brévent to the 2,525m summit. The middle section gains 1,000m of elevation in 3.5km — gradient sustained at approximately 28 percent. The official Marathon du Mont-Blanc KMV course uses a slightly different lower section but the climbing terrain is identical.
This route is the most commonly used vertical-kilometer training run in the European Alps for a reason. The gradient is honest. The trail surface is consistent. The summit view of Mont Blanc is the appropriate reward.
Aiguillette des Posettes Ridge **21km loop, 1,400m elevation gain — strenuous, alpine exposure**
From the village of Le Tour (12km north of Chamonix in the valley's upper section), the trail climbs to the Col de Balme on the Swiss border, then traverses the ridge of the Aiguillette des Posettes at 2,202m. Open ridge running with views of the Trient glacier on the Swiss side and the upper Chamonix valley behind. Exposed in alpine weather. Descent through Vallorcine.
This is the Marathon du Mont-Blanc 90K's most distinctive section. Running it in training is the most authentic preparation for the race.
Tour du Mont Buet **Variable — 25km to 40km depending on starting point, technical at altitude**
For runners building genuine mountain experience, the Buet (3,096m) above the upper Chamonix valley is the most accessible non-glaciated 3,000-metre summit in the region. Trail runs to the summit and back via the Refuge de la Pierre à Bérard. Requires alpine judgment, weather awareness, and ideally a partner. Not a "race the route" — this is mountain running at the discipline's outer edge.
Getting to Chamonix
By air: Geneva (GVA) is the primary access airport — 88km from Chamonix, 1 hour by direct shuttle. Multiple shared shuttle operators run frequently in summer (Alpybus, Chamonix Resorts, Mountain Drop-Offs). Approximate one-way fare: €30-40.
By train: Saint-Gervais-Les Bains-Le Fayet is the regional rail terminus. From Saint-Gervais, the Mont Blanc Express scenic mountain line runs every hour to Chamonix. From Paris, the full journey is approximately 6-7 hours via TGV to Saint-Gervais. From Geneva by train: approximately 3 hours via Bellegarde.
By car: From Geneva, A40 motorway to the Tunnel du Mont-Blanc exit, then RN205 to Chamonix. Approximately 1 hour 15 minutes. Be aware that Chamonix town parking is limited and expensive in summer; consider parking at one of the valley's outlying villages and using the free PassMontBlanc-funded public transport.
Connect with training partners, earn travel miles, and discover terrain worth crossing borders for.
Join ZealZagFollow us on InstagramLift Access for Training
The Chamonix lift system in summer is purpose-built for trail-running and hiking access. The relevant lifts for the running terrain:
- Brévent cable car (Chamonix town → Plan Praz 2,000m → Brévent summit 2,525m). Single-trip ticket: €23 (PassMontBlanc included with most accommodations).
- La Flégère cable car (Les Praz → La Flégère 1,894m). Connects to the upper Brévent area via the Grand Balcon Sud.
- Aiguille du Midi cable car (Chamonix → Aiguille du Midi 3,842m via Plan de l'Aiguille 2,317m). For Grand Balcon Nord access, ticket only to Plan de l'Aiguille.
- Le Tour cable car (Le Tour → Charamillon 1,850m). Access for the upper-valley Posettes ridge runs.
The PassMontBlanc card — included with most Chamonix accommodation stays of two nights or more — provides unlimited use of the regional bus network and discounts on lift access. Verify with your accommodation provider.
Best Season
Mid-June through mid-September is the window during which all five core routes are fully runnable. The KMV course on the Brévent is accessible from late May; the upper-elevation balcons typically clear of snow by mid-June. By October, the upper sections begin to receive snow, and lift services begin to wind down toward the late-month closure.
Late June through mid-July (the Marathon du Mont-Blanc window) is statistically the most stable Alpine weather period of the summer.
Training Notes for the Marathon du Mont-Blanc
If you are running the Marathon du Mont-Blanc 90K or Marathon, the single most important training-specific preparation is descent strategy. The race's accumulated vertical loss is greater than its accumulated gain (course finishes at lower altitude than several intermediate points). Quad-eccentric strength under fatigue is the limiting factor for most finishers in the lower half of the 90K results sheet. Three sessions per week of descent-focused training in the eight weeks before race day — even on lower-elevation hills — produces measurable race-day improvement.
The second key training emphasis is altitude exposure. The Marathon course summits twice above 2,000m; the 90K course summits at 2,360m. Athletes who have not trained at altitude above 1,500m within the four weeks before the race will pay measurably on the upper sections. Local high-altitude training in the week before the race — accessible via the cable car system — is a normal part of elite preparation here and worth replicating if your taper allows.
Local Tips
Eat: Chamonix's traditional Savoyard cuisine — tartiflette, fondue, raclette — is high-calorie comfort food calibrated for skiers but appropriate post-trail-run material as well. Le Cap Horn in the town centre is reliable; Le Café Rocher for breakfast and post-run coffee; La Maison Carrier for higher-end traditional cuisine. The bakery rotation — La Boulangerie d'Argentière in the upper valley, Le Fournil de la Vallée in central Chamonix — is what locals discuss most seriously.
Recovery: The town's swimming pool (Centre Sportif Richard Bozon) is a 25m heated indoor pool with adjoining ice-bath and sauna facilities. €4.50 entry. The most used recovery facility for visiting elite athletes.
Gear: Snell Sports (rue Joseph Vallot) is the town's serious trail-running shop — staffed by runners who race on the local terrain, knowledgeable about gear that works in this specific environment. Sanglard Sports for technical climbing and alpine equipment if your trip extends beyond pure running.
Culture: Chamonix is a French town but functions as an international mountain-sports hub. English is widely spoken in service contexts; the lift staff, shop staff, and most restaurant staff speak working English. Out of tourist contexts — at the bakery, the bus stop, the public pool — French is appropriate and appreciated.
FAQ
Can I run these routes without race entry? Yes. All five core routes are public trails. Permanent waymarking is excellent. Lift access is open to non-race participants throughout the summer.
How technical is the Marathon du Mont-Blanc 90K terrain? Approximately equivalent to a moderately technical Alpine ultra. There are no roped sections, no required scrambling, and no glacier travel. Terrain is single-track trail on alpine surfaces (loose rock, scree, occasional snow patches in early season). Runners comfortable on technical singletrack will find the surface familiar.
What's the difference between the Marathon du Mont-Blanc and UTMB? UTMB (Ultra-Trail du Mont-Blanc) is a 171km circumnavigation of the Mont Blanc massif held in late August. The Marathon du Mont-Blanc is a multi-distance race weekend held in late June in the Chamonix valley specifically. Different races; same town. Many elite athletes race both.
Is Chamonix expensive? Yes, particularly in summer. Mid-range accommodation in town runs €120-200 per night. Eating out, €15-25 per main course. Apartments outside the town centre (Argentière, Les Praz) are typically 20-30 percent cheaper than central Chamonix and remain trail-accessible.
For the 2026 Marathon du Mont-Blanc preview and current race week coverage, see our Marathon du Mont-Blanc 2026 field report.
