Arc 100K is the 82.7km ultra trail at Arc of Attrition by UTMB 2027 (Perranporth, United Kingdom). The race starts on January 23, 2027 at 10:00 AM. The time limit is 16 h.
The course climbs 2708m+. With 33m/km of climbing, this is a rolling, mostly runnable course. By gradient, 26% of the distance is uphill, 33% downhill and 41% flat. Surface: 60% trail, 16% road, 15% smooth, and 9% technical. Flat-equivalent effort: 104.3 FlatKM.
Poles bring little benefit here: only about 0.5km of pole-friendly terrain.
Quad damage risk is moderate (index 22 of 100), with 60% of the load in the first half: 0 descents deserve a plan and a couple of downhill sessions before race day.
On race day, start temperatures have historically ranged from 7°C to 11°C, with around 9°C at the highest point; the chance of precipitation is about 57%. Heavy rain of 10.0mm or more falls on about 11% of days around this date.
This page has a pacing and nutrition planner, a gradient matrix, an interactive elevation profile and historical weather for Arc 100K.
Other distances of Arc of Attrition by UTMB 2027Arc 100M (173km)·Arc 50K (49.4km)·Arc 20K (22.1km)
Official websitearcofattrition.utmb.world
