Col du Mail

Overview

Col du Mail is a Category 1 climb that packs a serious punch into 11.5 km. Rising from 648 m to a summit of 1602 m, it delivers a net elevation gain of 954 m at an average gradient of 8.32%. That average alone marks it out as a hard day — most climbs settle somewhere gentler — but the number that defines this ascent is the 27.92% maximum. Ramps like that are not something you ride through smoothly; they are moments you survive. With a total ascent of 891 m logged over the route, Col du Mail is relentless from the base to the line, offering little in the way of genuine recovery.

How the Gradient Unfolds

The gap between the 8.32% average and the 27.92% peak tells the story: this is not a uniform climb. An average that steep sustained across 11.5 km would be punishing on its own, but the presence of a near-28% wall means the true difficulty is spikier than the mean suggests. Expect long stretches that sit around or above the average, punctuated by pitches that briefly more than triple it. The 954 m net gain and 891 m of total ascent sit close together, which signals a road that climbs almost continuously — there is little descending mixed in to reset your legs. Plan your effort around the steep ramps rather than the average, because those are where the climb is won or lost.

Pacing Notes

On a climb averaging 8.32% for 11.5 km, pacing discipline matters more than raw power. Ride the sustained sections at or just below your FTP and save your matches for the 27.92% ramps, where you will inevitably surge well above threshold whether you want to or not. If you do not know your threshold number, estimate it first with the FTP estimator so you can set realistic targets before you start. Going out too hard on the lower slopes is the classic mistake here — with 954 m still to gain above the base, overcooking the first few kilometres leaves nothing for the steepest pitches higher up.

Gearing

Gearing is the single biggest lever you control on Col du Mail. For a climb this steep with pitches touching 27.92%, err generously toward easier ratios. A compact chainring paired with a wide cassette is the sensible baseline: 34×32 will get most trained riders up the sustained 8.32% sections, but the near-28% ramps are where that ratio runs out. If you have any doubt, fit 34×34 — the extra range keeps your cadence alive on the walls and protects your legs across the full 11.5 km. On a climb with 891 m of total ascent, spinning a low gear beats grinding a high one every time.

Summary

Col du Mail is a Category 1 test defined by its 27.92% maximum and its unbroken 8.32% average over 11.5 km. Pace conservatively, gear low, and respect the steep ramps.

Length: 11.5 km
Average gradient: 8.32%
Max gradient: 27.92%
Start: 648 m
Summit: 1602 m
Net gain: 954 m
Total ascent: 891 m
Category: 1