Format — Night race in pairs from Espoir category. Both runners stay together, pass checks and finish together. If either withdraws, both must withdraw. Full aid at Montenvers, drinks-only at refuge du Plan de l’Aiguille, then finish. Recommended UTMB index 240. Markers — 8 documented points, including 0 unconfirmed historical markers. On-course stations: Hôtel Montenvers (7,6 km) ; Refuge du Plan de l'Aiguille (14 km). GPS positions are used only from organiser maps or source GPX boundaries.
The Duo étoilé 2026 page brings together published data for this running route.
The route is listed from Chamonix-Mont-Blanc, France to Chamonix-Mont-Blanc, France, with 20.8 km and 1,313 m D+ on the page.
Listed organiser: Club des Sports de Chamonix.
Start / area
Chamonix-Mont-Blanc, France
Finish
Chamonix-Mont-Blanc, France
Edition
2026
Distance
20.8 km
Elevation gain
1,313 m D+
GPX track and calculated values
Calculated values for this track: 20.7 km of distance calculated from the GPX track · 1,357 m ascent calculated with ign_rge_alti_wld.
Distance follows the GPX geometry; ascent uses elevations derived from ign_rge_alti_wld. These calculations remain separate from the organiser's figures.
Source-page value: 21 km; distance calculated from the GPX: 20.7 km.
Source-page value: 1,450 m ascent; ascent calculated with ign_rge_alti_wld: 1,357 m.
Documented checkpoints and aid stations
Aid stations or life bases: 2 · listed water points: 2 · checkpoints: 1.
Caillet junction · km 4.8 — Eliminating cutoff: +1h15 from the race start.
Hôtel Montenvers · km 7.6 — Full aid station. Assistance is restricted to the 100 m zones before and after the station; supporters cannot enter the tent. Supplies vary by station and conditions; quantities are not guaranteed. Eliminating cutoff: +2h30 from the race start.
Refuge du Plan de l'Aiguille · km 14 — Drinks-only aid station; do not rely on solid food. Assistance is limited to authorised zones around the station. Eliminating cutoff: +4h30 from the race start.
Sources reviewed
Official sources: 9 · sources with a recorded review date: 9. Updates from the organiser always take precedence.
Latest recorded check: 9 October 2026.
Frequently asked questions
Is the Duo étoilé GPX available?
Yes. The track and its profile can be viewed here, and the file is available as a free download from this page.
Do these details replace the organiser's instructions?
No. This page makes sources easier to consult and separates published data from GPX calculations. Check the latest official instructions before the start.
Reference — This dossier covers the 2026 edition. Pages, rules, roadbook and maps were not all updated together. The uncertainty notes identify incompatible versions; no 2027 rule is inferred.
Format — Night race in pairs from Espoir category. Both runners stay together, pass checks and finish together. If either withdraws, both must withdraw. Full aid at Montenvers, drinks-only at refuge du Plan de l’Aiguille, then finish. Recommended UTMB index 240.
2026 starts (Europe/Paris) — 27/06 : 19h30.
Bib — EMC2, Place du Mont-Blanc, in person by appointment: Thursday 25 or Friday 26 June 9h–21h, Saturday 27 June 9h–18h. Bring the collection card, photo ID and equipped race bag. Book by 19 June at 17:00; Thursday opening differs between 09:00 and 09:30 in the sources, so use the confirmed slot.
Markers — 8 documented points, including 0 unconfirmed historical markers. On-course stations: Hôtel Montenvers (7,6 km) ; Refuge du Plan de l'Aiguille (14 km). GPS positions are used only from organiser maps or source GPX boundaries.
Self-sufficiency — Carry food, water and equipment between stations. Mandatory water capacity is a carrying minimum, not a consumption rate. Products and quantities may vary; carbohydrate and sodium amounts per serving are not published.
Aid stations — The general on-course menu lists bread, tomme cheese, saucisson, cakes, Tucs, seasonal fruit, MX3 products and broth. Drinks include still water, sparkling water with electrolytes or syrups, energy drink and weather-dependent tea. The menu does not guarantee every item at every station; drinks-only stations do not list solid food.
Finish — The general menu lists a diot hot dog with a possible vegetarian option, tomme cheese, cakes and fruit; water, syrup drinks and weather-dependent tea. Beer is excluded from Mini-Cross and The Young Race. Cups, bowls and cutlery are not provided at aid stations.
Assistance — Only checked runners wearing a visible bib enter aid stations. Supporters remain outside the tent unless accredited. Personal assistance is limited to 100 m before and 100 m after stations; pacing and assistance elsewhere are prohibited.
Times and cutoffs — Estimated passage times are not cutoffs. Intermediate cutoffs use the final wave when there are multiple waves; the maximum race time runs from the runner’s own wave. Missing a cutoff means withdrawal from the race. The jury may change routes, starts and cutoffs for safety.
Checks and bib — Keep all mandatory equipment from bib collection to the finish and accept checks. The bib must be fully visible and must not be attached to the backpack; bib belts are allowed. Missing equipment, shortcuts or prohibited assistance may incur penalties.
Withdrawal — Give your bib number to an organiser or race control; never leave the route without reporting. The roadbook lists a text message containing bib number + ABANDON + location to +33 6 10 55 12 11. Arrange your return and carry cash for transport if needed.
Rescue — Help anyone in danger and alert the nearest station or rescue control. The 2026 roadbook lists +33 9 79 98 18 22, +33 6 10 55 12 11 and 112. Keep your phone switched on and audible. Medical staff may order withdrawal or evacuation; rescue delays and individual station services are not guaranteed.
Environment — Follow marked trails, retain rubbish and use station sorting facilities; do not trample meadows. Supporters remove their own waste. No animals are allowed in the race; dogs are prohibited in the Aiguilles Rouges reserve and at aid stations.
Penalties — Refusing checks, deliberate littering, failing to help or refusing instructions may lead to disqualification. Fraud and disrespect may result in long-term exclusion. The official table sets time penalties by race; officials and the jury make decisions.
2026 entry — Personal online registration; bib swapping, gifting and resale are prohibited. The organiser requires proof of address and carbon compensation. Bus/train entries require more than half the journey by public transport, a return ticket covering the event and proof by 4 May 2026; eligible residents may use ViaCham instead.
2026 health documents — The rules accept specified FFA licences or PPS for adults; minors use a health questionnaire, with a certificate when needed. They require PPS submission by 31 May 2026 and state three-month validity. These are edition-specific entry conditions, not current medical rules for another year.
Insurance — The rules require personal accident cover including search and evacuation; France and Switzerland for the 90 km. Organiser liability cover does not replace it. Exceptional rescue and return costs may be payable by the runner; the organiser does not cover lost, stolen or damaged equipment.
2026 changes and refunds — Changes to specified shorter formats require available places and a written request by 30 April 2026. Duo teams may replace one partner once by that date, retaining transport eligibility. Entry is final without ordinary refund unless cancellation insurance was bought at registration; bank fees remain excluded.
Weather and force majeure — The organiser may change or stop a race and notify runners by SMS, email and website. The rules describe a 60% refund of collected entry fees for specified force-majeure cases, excluding donations, insurance, extras, carbon compensation and bank fees; postponement claims were due by 15 July 2026. No fallback course is fabricated from the GPX.
After the race — The bib grants access to showers at Centre Sportif Richard Bozon and cable-car descent after the 23 km or KV. Put timing chips in recycling bins. The roadbook includes 2025 shower dates: 2026 shower hours are unconfirmed. There is no bag storage at bib collection; no on-course drop-bag service is confirmed per station.
Images and data — The rules provide for use of participant images and a licensing framework for event filming. The listed contact for registration data and publication requests is club@chamonixsport.com; publication objections must be sent at least 30 days before the event. The organiser may revise the rules until the day before the first race.
2026 health and eligibility — FFA Athlé Compétition, Athlé Entreprise and Athlé Running licences are accepted; Santé and Encadrement are excluded. Minors complete the questionnaire with their legal representative and require a certificate under six months old if any answer is positive. An incomplete file prevents bib collection and starting. The committee may refuse entry for medical incompatibility, documented fraud or unethical behaviour.
Historical entries — For 90/42/23 km and Duo: 10% valley entries, 40% bus/train and 50% lottery; one preregistration for one race only. Lottery groups of 2–10 on the same race use a shared code and receive the same outcome; odds remain the same as individual entry. Short formats use direct entry until sold out.
2026 entry calendar — Listed openings were in October/November 2025: valley 20 October, train/bus 22 October, lottery 23–30 October. The rules give incompatible lottery payment deadlines, 5 November 14:00 or 17 November 17:00; both remain conflicting historical dates. For a future edition use its own dates.
2026 permitted changes — Subject to places: 90/42/23 km to KV or 10 km; one Duo runner whose partner is injured to KV or 10 km; KV to 10 km; Young Race to 10 km and vice versa. Other conversions are excluded; the runner must request in writing by 30 April without refund. Duo’s single partner replacement uses the runner area; replacement T-shirt size is not guaranteed.
Sanction duration — The entry section lists a ten-year ban for bib exchange/resale, while the penalty table lists lifetime disqualification for cheating and disrespect. The discrepancy is retained without selecting a duration. Refusing checks, deliberate littering, failing to help and refusing instructions mean disqualification.
Poles — Allowed only if carried for the entire race; starting without poles and collecting them later is prohibited. Weather-dependent recommended kit: hat, tights, gloves, cap and extra water; strapping tape for longer formats, bowl/spoon when not mandatory.
2026 fee — €85 per team before 31 March; €85 from 1 April to 27 June. Carbon compensation, donations, insurance and extras are separate from the entry fee.
Time penalties — Missing mandatory equipment: 15 min; assistance outside zones, hidden bib or course shortcuts: 15 min. Missing safety equipment and/or more than three missing items may also mean disqualification for 90/42/23 km and Duo; officials apply the table and the jury decides other breaches.
Night return — 2026 transport guide, p. 12: paid Chamo’nuit €4.50 from 20:30 to 01:00; free organiser shuttles Les Houches–Argentière from 01:30 to 02:30, approximately every 30 min. Report at finish aid. Lifts are closed during the race.
Checks before the start
Check document versions and edition-specific uncertainty notes.
Book bib collection and prepare supporting documents.
Check each mandatory item and phone/light batteries.
Identify stations, applicable cutoffs and return options.
Save this edition’s race numbers and report any withdrawal.
Differences and information still uncertain
These items are shown explicitly so an approximation is never presented as official data.
No 2027 data is confirmed. Source GPX files do not contain waypoints: documented markers come from tables, rules and maps, with separate provenance.
Station coordinates missing from maps are not reconstructed. Medical services, drop bags, quantities and per-serving nutritional composition remain unknown when unpublished.
Croisement Caillet: 4 km on the page, 4.5 km in the rules and 4.8 km in the roadbook. Refuge: 13.7 km on the page, 14 km in the roadbook. Finish: advertised 21 km, table 21.4 km; roadbook values are retained for markers.
The rules describe two full aid stations, while the detailed page lists full aid at Montenvers and drinks-only at Plan de l’Aiguille; the detailed list is retained.
Check the information
Sources and provenance
These links point to the documents used. The organiser's instructions remain authoritative if they change.
Official Marathon du Mont-Blanc 2026 programmeOfficial
Race feedback
Have you already run this race?
Share your feedback: conditions, course marking, atmosphere, difficulty or tips for future participants.