Passo Prà della Rosa

Overview

Passo Prà della Rosa is a climb that leaves no room for hiding. Over 15.1 km it hauls you from a valley floor at just 62 m up to a summit of 1445 m, a net gain of 1383 m. The average gradient reads 9.19%, and unlike many long passes that dilute their steepest ramps with flatter recovery stretches, this one holds that number honestly across nearly the whole ascent. With a total ascent of 1377 m packed into a distance that never lets up, it earns its HC (hors catégorie) rating without argument — the hardest tier on the scale, above categories 1 through 4.

How the Gradient Unfolds

The shape of Prà della Rosa is defined by consistency rather than a single wall. A 9.19% average sustained over 15.1 km means there is essentially nowhere to freewheel and recover. The near-identical figures for net gain (1383 m) and total ascent (1377 m) confirm this: the road climbs and keeps climbing, with almost no descending or flat to interrupt the effort. That 6 m difference between the two tells you the profile is a clean, upward line — you gain elevation from the first pedal stroke and don't stop until the 1445 m summit. Expect the gradient to sit in high single digits for kilometre after kilometre, the kind of grade that feels manageable for five minutes and merciless after fifty.

Pacing Notes

On a climb this sustained, pacing is everything. Because there are no flat sections to soft-pedal, your effort should be governed by a wattage ceiling you can hold for the full duration rather than by feel. Anchor your target to your FTP: for most riders a long HC ascent like this is best ridden just below threshold, leaving a small buffer for the fact that 15.1 km at 9.19% will take a long time to clear. If you don't have a current threshold number, run yours through the FTP estimator before you commit to a pace. Start conservatively — the temptation to push early on fresh legs is exactly what blows riders apart on a climb with 1383 m of unbroken gain. Meter your effort so the last quarter, above the point where fatigue compounds, is where you spend what's left rather than where you crack.

Gearing

Do not under-gear this climb. A 9.19% average sustained for 15.1 km demands the widest ratios most riders can fit. A compact 34-tooth chainring paired with a 34×32 low is the sensible minimum, and many riders will be glad of a 34×34 for the long grind where cadence tends to collapse. The extra sprocket buys you the ability to keep spinning rather than grinding, which protects your legs across a climb this long. If your setup allows an even easier ratio, use it — there is no prize for suffering on the wrong gear here.

Summary

Passo Prà della Rosa is a pure, relentless HC ascent: long, uniformly steep, and unforgiving of poor pacing or heavy gearing. Respect the numbers, ride to your threshold, and gear low.

Length: 15.1 km
Average gradient: 9.19%
Max gradient: n/a
Start: 62 m
Summit: 1445 m
Net gain: 1383 m
Total ascent: 1377 m
Category: HC