San Marco Pass

Overview

San Marco Pass is a hors catégorie monster, the kind of ascent that rewards patience and punishes ego. It runs 25.9 km from a valley floor at 263 m all the way to a 1990 m summit, stacking up 1727 m of net elevation gain over its length. The total ascent nudges just slightly higher at 1728 m, a hint that there's a brief respite somewhere on the way up before the road tilts skyward again.

At an average gradient of 6.66%, this is a sustained effort measured in tens of minutes, not seconds. There are no shortcuts here — just a long, honest grind that asks you to hold a steady rhythm for the better part of an hour or more.

How the Gradient Unfolds

The numbers tell a story of relentlessness rather than surprise. With a 6.66% average holding across almost 26 km, the climb never really lets you coast. The 1 m gap between the 1727 m net gain and the 1728 m total ascent means the profile is almost entirely uphill — there's virtually no descending to break the effort, so you climb nearly every metre you cover.

The sting lives in the 14.48% maximum gradient, more than double the average. Expect ramps that spike well beyond what your legs settled into, likely on the steeper mid and upper slopes where the road pitches up sharply. When the average sits at 6.66% but the max more than doubles it, you know there are pinches waiting to break your cadence.

Pacing Notes

On a climb this long, pacing is everything. Anchor your effort to your FTP and aim to hold a percentage you can sustain for the full 25.9 km — going out too hard in the first few kilometres is the classic way to blow up before the summit. If you're unsure of your number, run the FTP estimator first and build your target power from there.

Treat the 14.48% ramps as moments to spend a little extra, then settle back to your steady effort rather than chasing lost time. With a 1990 m summit, the thinning air on the upper slopes will quietly shave a few watts off your ceiling, so leave a small reserve for the final kilometres.

Gearing

For an HC climb averaging 6.66% with pitches to 14.48%, gear low and gear early. A compact 34-tooth chainring paired with a wide-range cassette is the sensible baseline. A 34×32 will get most fit riders up the sustained sections, but on the steepest ramps you'll be grinding.

If you have any doubt about your climbing legs — or you're carrying fatigue into a 25.9 km effort — fit a 34×34. That extra sprocket keeps your cadence alive on the 14.48% pinches and lets you spin rather than mash through the hardest metres. On a climb this long, easier gearing isn't weakness; it's what keeps you turning the pedals all the way to 1990 m.

Summary

San Marco Pass is a true HC test: long, sustained, and unforgiving, with just enough gradient variation to keep you honest from 263 m to the 1990 m summit. Pace it with your FTP, gear it low, and respect the distance.

Length: 25.9 km
Average gradient: 6.66%
Max gradient: 14.48%
Start: 263 m
Summit: 1990 m
Net gain: 1727 m
Total ascent: 1728 m
Category: HC