Sustenpass

Overview

Sustenpass is a hors catégorie climb, the hardest rating in the book, and its numbers explain why. You cover 24.9 km at an average gradient of 6.43%, starting at 625 m and topping out at 2230 m. That is a net elevation gain of 1605 m in a single, unbroken effort — the kind of climb that rewards patience far more than aggression. With a total ascent of 1568 m recorded across the route, the road climbs almost relentlessly, giving back only a little before pushing on again toward the summit.

How the Gradient Unfolds

An average of 6.43% across nearly 25 km sounds steady, and much of Sustenpass is. But averages hide the sting: the maximum gradient hits 13.66%, more than double the average. That means the climb is not evenly paved — there are ramps that spike hard above the mean, balanced by shallower stretches that let the average settle back to 6.43%. Expect the pattern of a long alpine pass: sustained mid-single-digit grades that occasionally rear up. The gap between the 6.43% average and the 13.66% max is your warning to leave something in reserve. Nearly 25 km is a long time to be climbing, and the pitches that matter are the ones deep in the effort, not the early ones.

Pacing Notes

On a climb this long, pacing is everything. The single most useful reference point is your FTP — the power you can sustain for roughly an hour. Sustenpass will take most riders well beyond an hour, so target a wattage comfortably below threshold for the bulk of the 24.9 km, then allow yourself to press only on the steepest ramps toward 13.66%. Going out too hard on the lower slopes is the classic error here; with 1605 m of net gain ahead, an early overreach compounds badly. If you do not know your threshold, estimate it first with the FTP estimator, then set a realistic ceiling and hold it. Ride the first two-thirds within yourself and you will still have legs for the summit at 2230 m.

Gearing

For an HC climb of 24.9 km averaging 6.43% with ramps to 13.66%, gear low and gear generously. A compact chainring paired with a wide-range cassette is the sensible baseline. A 34×32 will get many trained riders over the pass, but on the steepest sections — where the gradient more than doubles the average — a 34×34 gives you the extra spin to protect your cadence and your legs. If you tend to grind, or you are carrying fatigue from the long approach, err toward the 34×34. Keeping the cadence up over 1605 m of climbing saves the muscular effort you will want in reserve near the top.

Summary

Sustenpass is a genuine hors catégorie test: long, sustained, and steep enough in places to demand respect. Pace it off your threshold, gear low, and treat the 13.66% ramps as the moments to spend — not the opening kilometres.

Length: 24.9 km
Average gradient: 6.43%
Max gradient: 13.66%
Start: 625 m
Summit: 2230 m
Net gain: 1605 m
Total ascent: 1568 m
Category: HC