Portella Tre Fontane

Overview

Portella Tre Fontane is a long, honest Italian climb that rewards rhythm over fireworks. It runs 18.4 km from a low base of 138 m to a summit of 1075 m, a net gain of 937 m at an average gradient of 5.09%. That average tells the real story: this is a sustained effort, not a wall. The steepest pitch tops out at 10.49%, but those moments are the exception on a road that mostly hovers in the mid-single digits. With a total ascent of 975 m across its full distance, the climb includes a little extra vertical beyond the net figure, hinting at brief dips or flattening sections where the road briefly relents before pointing up again. Rated Category 1, it sits one rung below the hardest hors catégorie ascents, which is exactly right for a climb this length at this gradient.

How the Gradient Unfolds

At 5.09% average over 18.4 km, Portella Tre Fontane is a climb of accumulation rather than shock. The gap between the total ascent of 975 m and the net gain of 937 m — 38 m — tells you the profile is not perfectly monotonic; somewhere the road eases or drops slightly before resuming its upward march. Expect long stretches near the average where you can settle into a cadence, punctuated by the occasional steeper kick toward the 10.49% maximum. Those ramps are where the climb bites, roughly doubling the average pitch, so they demand a deliberate change of gear rather than a lunge. The overall shape favors riders who can hold a steady power output and resist chasing every gradient change.

Pacing Notes

On a climb this long, pacing is everything. The temptation on the lower slopes near 138 m is to push hard while the legs feel fresh, but 18.4 km at 5.09% will punish an early overcommitment. Aim to ride the bulk of the climb just below your FTP, saving headroom for the steeper ramps that approach 10.49%. If you do not know your threshold, run the numbers through the FTP estimator before you plan your effort — it turns guesswork into a target you can actually hold to the 1075 m summit. Meter your effort so the last few kilometers, still climbing toward the top, are the strongest, not a survival crawl.

Gearing

For a Category 1 climb of 18.4 km with pitches to 10.49%, give yourself range to spin. A compact chainring paired with a wide-range cassette is the sensible baseline: a 34×32 will carry most riders comfortably through the sustained 5.09% sections and the steeper ramps. If you weigh more, ride heavier gear, or simply want to protect your legs over 937 m of climbing, size up to a 34×34 so you can keep the cadence high and the strain low on the hardest kicks. Both options keep you seated and turning rather than grinding.

Summary

Portella Tre Fontane is a classic long Category 1 ascent: patient, steady, and best ridden with a plan. Respect the distance, pace to your threshold, and gear generously, and the 1075 m summit is a fair reward for 937 m of consistent effort.

Length: 18.4 km
Average gradient: 5.09%
Max gradient: 10.49%
Start: 138 m
Summit: 1075 m
Net gain: 937 m
Total ascent: 975 m
Category: 1