Colle del Mulo

Overview

Colle del Mulo is an HC (hors catégorie) climb in Italy, running 23.8 km from a start elevation of 749 m to a summit at 2,485 m. On paper it delivers 1,736 m of net elevation gain at an average gradient of 7.3%. Those numbers alone place it among the longer sustained efforts you can take on in a single climb — nearly 24 kilometers of near-continuous uphill work that rewards patience over aggression.

But the net figure understates the workload. Total ascent is 2,459 m, which is 723 m more than the net gain. That gap is undulation: the road repeatedly gives back elevation before clawing it back again. Every meter you descend mid-climb is a meter you re-climb, and none of it counts toward getting you higher. Expect the effort to feel harder than a smooth 1,736 m ascent would suggest, because you are effectively climbing over 2,400 m of real vertical.

How the Gradient Unfolds

The 7.3% average is a blend, not a constant. With 24.12% recorded as the maximum, the profile clearly hides pitches far steeper than the mean, offset by flatter and even downhill sections that drag the average down. Do not trust the average to pace individual ramps.

• Flatter and recovery sections where the road eases or briefly drops — use these to eat, drink, and reset your legs
• Repeated short climbs stacked through the middle, the source of the 723 m of "extra" ascent
• A steepest ramp reaching 24.12%, well above anything the average prepares you for

Pacing Notes

On an undulating climb like this, chasing an even speed is a trap: holding pace on a 24% ramp will spike your power far past threshold and cost you the summit. Pace to an even effort instead. Anchor your climb to a target sustainable power output and let your speed rise and fall with the gradient — slow on the ramps, faster on the flatter stretches. On the brief descents, soft-pedal rather than surging.

If you don't know your ceiling, run the FTP estimator before the ride and set a climbing target a touch below it, given the 23.8 km duration.

Gearing

The 24.12% maximum gradient governs your gear choice, not the 7.3% average. Bring a compact or sub-compact chainset paired with a wide-range cassette — a 34×32 or 34×34 is a sensible minimum for the steep pitches. On a climb this long, spinning a low gear preserves your legs across the full 23.8 km far better than grinding.

Check your setup before the ride: confirm the cassette, derailleur capacity, and that your smallest gear actually engages cleanly under load.

Summary

• Length: 23.8 km
• Average gradient: 7.3%
• Maximum gradient: 24.12%
• Net elevation gain: 1,736 m
• Total ascent: 2,459 m
• Category: HC

Colle del Mulo is a long HC test where the undulation, not the average gradient, defines the day. Pace to effort, gear for the 24% ramps, and treat the 723 m of extra ascent as work you have to plan for rather than a surprise you meet halfway up.