Sella Somdogna / Siele Sompdogne

Overview

Sella Somdogna / Siele Sompdogne is a long, serious category 1 ascent that stretches 14.2 km from a valley floor at 422 m up to a summit of 1397 m. That works out to 975 m of net elevation gain, with the total ascent measured at 970 m — a sign that this is an almost relentlessly uphill road rather than a rolling profile with recovery dips. At an average gradient of 6.87%, it sits firmly in the range where sustained tempo effort meets genuine endurance, and the 18.24% maximum tells you the average hides some teeth.

How the Gradient Unfolds

The headline average of 6.87% is a useful anchor, but a climb of this length rarely holds a single slope. The gap between the 6.87% average and the 18.24% maximum is 11.37 percentage points, which means there are stretches steep enough to force you out of any comfortable rhythm. With total ascent (970 m) sitting just 5 m below the net gain of 975 m, there is almost no descending to reset your legs — nearly every metre you climb, you keep. Expect the pitches to arrive in waves: sections at or above the average that make the effort feel honest, punctuated by short walls climbing toward that 18.24% figure. Over 14.2 km, that adds up to a climb where consistency matters far more than any single heroic acceleration.

Pacing Notes

On a climb this long, going out too hard is the classic mistake. With an average of 6.87% over 14.2 km, your best result comes from settling into a steady effort anchored to your FTP and holding it. Target a wattage you can sustain for the full duration — this is a 40-plus-minute effort for most riders, so treat it like a long threshold interval rather than a series of surges. Save a little in reserve for the ramps toward 18.24%, where the gradient will spike your power whether you like it or not. If you are not sure what number to anchor to, run the FTP estimator first and build your pacing plan around the result. Climbing a few beats under threshold early pays dividends when the steepest sections arrive.

Gearing

With a net gain of 975 m and pitches reaching 18.24%, gearing is not the place to be brave. A compact 34-tooth front chainring is the sensible baseline here. Pair it with at least a 34×32 for the sustained 6.87% grind, and if you have any doubt about your climbing legs — or you are riding this at the end of a long day — a 34×34 gives you the extra spin to keep cadence up on the ramps without wrecking your knees. On a 14.2 km climb, protecting your cadence on the steep bits is what lets you finish strong rather than survive.

Summary

Sella Somdogna / Siele Sompdogne rewards patience: pace it to your threshold, gear low, and let the 14.2 km come to you rather than chasing it. It is a category 1 test of endurance with just enough steepness to punish an over-eager start.

Length: 14.2 km
Average gradient: 6.87%
Max gradient: 18.24%
Start: 422 m
Summit: 1397 m
Net gain: 975 m
Total ascent: 970 m
Category: 1