Col du Tarent

Overview

Col du Tarent is a long, sustained category 1 effort that rewards patience over aggression. From a start elevation of 388 m, the road unwinds for 25.7 km before topping out at 1792 m. That is a net elevation gain of 1404 m, delivered at an average gradient of 5.46%. On paper the average reads gentle, but the total ascent of 1623 m tells the fuller story: there are dips and false flats hidden inside those kilometres, meaning you climb more than the net figure alone suggests. This is a climb measured in fractions of an hour, not minutes.

How the Gradient Unfolds

The 5.46% average is an honest number for a climb of this length, but averages smooth over the truth. The gap between the net gain of 1404 m and the total ascent of 1623 m — a difference of 219 m — means the profile is not a clean, uniform ramp. Somewhere along those 25.7 km the road eases, even descends, then reclaims what it gave back. That variability is confirmed by the headline max gradient of 39.96%, a wall so steep it dwarfs the average many times over. You will not sit at 39.96% for long, but knowing a pitch that severe exists changes how you ration your effort on everything before it.

Pacing Notes

On a climb this long, discipline beats bravado. Your best guide is FTP: ride the bulk of the 25.7 km at a controlled percentage of it and hold spare capacity for the steep pitches, where the gradient can spike toward that 39.96% max. Going into the red early, with a full 1404 m of gain still overhead, is the classic way to blow apart on the upper slopes. If you are unsure of your number, run it through the FTP estimator before you set your target power. Treat the false flats — the sections responsible for the 219 m difference between net gain and total ascent — as recovery windows, not places to attack. Settle into a rhythm you could sustain for the full ascent and let the mountain come to you.

Gearing

With 25.7 km and 1623 m of total ascent under you, gearing is not vanity — it is survival. A compact 34-tooth inner chainring is the sensible baseline here. Pair it with at least a 32-tooth cassette sprocket, so a 34×32 gives you a bailout for the sustained middle. Given the 39.96% max gradient, though, an even wider 34×34 is the smarter choice for most riders: that extra sprocket keeps your cadence alive when the road rears up and spares your knees over an effort this long. If your bike will take it, fit the 34×34 and be grateful for it near the top.

Summary

Col du Tarent is a full-value category 1 climb: long, varied and topped by a genuinely brutal pitch. Pace it by FTP, gear it generously, and respect the difference between the net gain and the total ascent. Do that, and the 1792 m summit is well within reach.

Length: 25.7 km
Average gradient: 5.46%
Max gradient: 39.96%
Start: 388 m
Summit: 1792 m
Net gain: 1404 m
Total ascent: 1623 m
Category: 1