La Gravel Tro Breizh

Gravel Tro Breizh is an unsupported ultra-distance bikepacking adventure across Brittany, France, organised by Erminig. Established in 2018, the event takes riders through the region’s rugged countryside, forest tracks, agricultural paths and quiet backroads. The 2027 edition celebrates its 10th anniversary, with a challenging route of approximately 1,350 km and 19,000 metres of elevation gain.

Route and terrain

Starting and finishing at Lac de Trémelin, west of Rennes, the route explores the diverse landscapes of Brittany. Riders encounter granite trails, forest paths, farm tracks, quiet asphalt roads and occasional technical singletrack. Although much of the course is relatively rideable, Brittany’s rolling terrain delivers relentless short climbs and demanding elevation changes. Gravel bikes, monstercross bikes and mountain bikes are all suitable, with tyre choice depending on riding style and technical ability.

The route is redesigned every year, revealing different corners of Brittany and keeping the exact course a surprise until shortly before the event.

Unsupported bikepacking challenge

Gravel Tro Breizh follows a strict self-supported format. Participants must complete the entire route without outside assistance, managing their own navigation, nutrition, mechanical repairs and sleep. The event is non-competitive, but riders must keep moving within a 180-hour time limit, giving them seven and a half days to finish.

Live GPS tracking allows progress to be followed throughout the adventure. With its combination of technical trails, constant climbing and complete self-reliance, Gravel Tro Breizh is a demanding challenge for experienced ultra-distance cyclists looking for an authentic off-road adventure.