Gran Trail Courmayeur 51km: One of Europe's Steepest 51km Races — Average Uphill Rank 41/390, 3,500m D+ at 68.6 m/km in the Mont Blanc Massif Above Courmayeur

The Gran Trail Courmayeur 51km (marketed as GTC55 on the official site — approximately 55km per the race website, stored as 51km in Airtable) is a loop starting and finishing in Courmayeur, Piazza Abbé Henry, in the Aosta Valley of Italy, through the Mont Blanc massif. Official D+: 3,500m over 51km, giving 68.6 m/km climbing density (rank 50/390 European trail races — top 13%). The top single ascent rises 1,064m at +17.56% average gradient over approximately 6.06km, beginning around km 6.45 (rank 104/390). The top single descent drops 916m at -22.29% average gradient over approximately 4.11km from around km 30 (rank 131/390). Pct_flat is 13.86% (reliable; rank 111/390). Average uphill gradient ranks 41st of 390 European trail races (top 11%). Average downhill gradient ranks 328th of 390 on the inverted scale — placing this course in the steeper 16% of the European database for average descent. The course was first run in 2013 and is organised by TorX / VDA Trailers.

Among 390 European trail races in the DTR database, the Gran Trail Courmayeur 51km ranks in the top 11% for average uphill gradient (rank 41/390): only 40 European trail races of any distance maintain steeper average climbing gradients. D+/km ranks 50/390 at 68.6 m/km (top 13%) — comparable to the most vertically dense UTMB World Series races despite the shorter distance. Top single ascent ranks 104/390 (top 27%): 1,064m at +17.56% over 6km is one of the largest individual climbs in the database for a 51km-class race. Top single descent ranks 131/390 (top 34%): 916m at -22.29% average over 4.11km. Average downhill gradient ranks 328/390 inverted (top 16% steepest descent effort). Pct_flat ranks 111/390 at 13.86%. Combined, these metrics confirm the GTC51 as a course where extreme steepness defines both the uphill and downhill effort throughout — not a single spike but a sustained technical gradient through the Mont Blanc terrain above Courmayeur.

Both races are organised by TorX / VDA Trailers (Valle d'Aosta Trailers), based in Courmayeur. TorX runs the full spectrum from GTC51 (51km) and GTC100 (100km) through to TOR330 (Tor des Géants, 330km) and TOR450 (450km). They share the same registration portal (my.experience.torxtrail.com), organisational culture, and trail network in the Aosta Valley and Mont Blanc massif. Gran Trail Courmayeur has been running since 2013 and is in its 14th edition in 2026. La Sportiva is the title sponsor. For GTC100 finishers, a guaranteed Tor des Géants ballot entry is included — verify whether this benefit extends to GTC51 finishers at gtcourmayeur.com before making race selection decisions.

Yes — both the Gran Trail Courmayeur 51km (GTC55) and the sibling 100km were sold out for the 2026 edition (race date July 11, 2026). The race historically sells out quickly after registration opens; for 2026 the 100km registration opened November 3, 2025, with the 51km on a similar or simultaneous schedule. For the 2027 edition, monitor the TorX portal at my.experience.torxtrail.com and the official race site at gtcourmayeur.com/en/ for registration opening announcements. Entry for the 51km is EUR 110 (~EUR 2.16/km); no additional platform fee was noted beyond standard insurance options. La Sportiva is the title sponsor.

Extremely hard. GTC 100km covers ~100km and ~7,400m D+ (official; Airtable records 6,050m — exact figure under review) through the Mont Blanc massif, with a distance-weighted average uphill gradient of 15.61% and 13.29km of terrain exceeding 20% gradient. The course includes fixed chains on exposed cliff sections, possible snowfields, and a 10 PM nighttime start — meaning even elite runners navigate the most technical terrain in darkness. The first 35km to La Thuile is described in race reports as the most technical terrain in any normal trail race. The Life Base at km 76 is preceded by an 800m climb at approximately 30% average gradient. Maximum cutoff: 33 hours. DNF rate: approximately 25.8% (135 of 524 starters in the 2025 edition).