Stelvio from Prato: 48 hairpins, 25 km, and how to pace them

The Stelvio is 2,757 m high, and from Prato allo Stelvio it is the longest sustained climb most riders will ever do: 25 km and about 1,850 m of height gain without a single meaningful descent. The 48 numbered hairpins on this side count down to the top, so every bend tells you exactly how much is left. That is a gift on a good day and a slow torment on a bad one. Here is how the climb is built, how to pace a two-hour effort, and how to ride it on your trainer before you go.

The climb, in three parts

The Stelvio National Park publishes the checkpoints for the ascent from Prad, as the town is called in German: 910 m at the start, Trafoi at 10.7 km and 1,530 m, Franzenshöhe at hairpin 22 after 18.3 km and 2,190 m, and the pass at 25.0 km and 2,760 m. Those four points describe the climb better than any average.

• Prato to Trafoi: the valley. The first 10 km climb 620 m through Gomagoi in a narrow wooded valley, mostly between 5 and 7%. There are no hairpins yet, so it feels like a long approach rather than the climb. It isn't an approach. Riders who arrive at Trafoi already breathing hard have lost the Stelvio there.
• Trafoi to Franzenshöhe: the forest hairpins. From hairpin 48 just above Trafoi the road starts switching back through the trees, and this middle third is the steepest sustained part of the climb. The park's own numbers give about 660 m of climbing in 7.6 km, close to 9%. It is also where the climb's steepest kilometre is, at 9.8% on our track.
• Franzenshöhe to the pass: the wall. Above the hotel at Franzenshöhe the trees stop and you see it all at once: the famous stack of hairpins on the bare mountainside, with the pass buildings at the top looking much closer than they are. It is 6.7 km and 570 m more, a little gentler than the forest. But you are above 2,200 m now, the air is thinner and you have been climbing for well over an hour.

How to pace two hours of climbing

For most amateurs the Stelvio from Prato takes between an hour and a half and two and a half hours. That makes it a threshold-adjacent endurance effort, not a threshold one. The mistake everybody makes is riding the valley at the power they would hold on a 20-minute climb at home.

• Start at 80–85% of FTP and stay there. Over two hours that is already hard. The hairpins in the forest will push you higher on their own, so let them, then come back down on the straights. Our guide to pacing a climb with power covers why an even effort beats a hard start every time on a climb this long.
• Expect less power at the top. Above 2,000 m, the same effort gives fewer watts. If your power drops in the last 5 km at the same breathing and heart rate, you haven't faded. Ride by feel up there, not by the number.
• Gear lower than you think. The road was built for horse-drawn traffic and never gets brutal, but 25 km of 7–9% wears down a 39×25. A compact with a 32 or 34 at the back keeps your cadence up in the forest. See gearing for climbing.
• Eat in the valley. By Franzenshöhe it is too late to fix a fuelling mistake. Aim for 60–90 g of carbohydrate an hour from the start; fuelling long rides has the numbers.

Why it is the Stelvio

The road was built between 1820 and 1826 under the Austrian Empire, directed by the engineer Carlo Donegani, to link Lombardy with Tyrol over the mountains. Two centuries later it is still the second-highest paved pass in the Alps.

Its place in cycling dates to 1 June 1953, when the Giro d'Italia crossed it for the first time. Hugo Koblet of Switzerland was in the pink jersey. On the Stelvio, Fausto Coppi attacked, reached the top alone and won the stage into Bormio. Koblet crashed on the descent and lost his lead, and Coppi took the fifth and last of his Giro wins. The Giro's own history notes he did it on a 46×23 bottom gear. Since then the race's highest summit has been called the Cima Coppi in his honour, and when the Stelvio is on the route it is almost always the Cima Coppi.

When to go, and what to watch for

• Season. The pass is closed in winter and opens when the snow is cleared, usually in late spring. In the shoulder months the top can be bitterly cold with snow banks beside the road even when Prato is warm. Pack a gilet and full gloves for the descent whatever the forecast in the valley says.
• Traffic. In summer the road is busy with motorbikes and cars, and the hairpins are tight. Ride early: the road is quiet before nine, and you will have the top to yourself.
• Stelvio Bike Day. Once a year, usually at the end of August, the road is closed to motor traffic from 8:00 to 16:00 on all three sides: from Trafoi, from Bormio and from the Swiss side over the Umbrail. It is free, it isn't a race, and it is the best day of the year to ride the climb. Check the park's events page for the date.
• The descent. Coming back down to Prato, the park asks riders not to use the cycle path between Stilfserbrücke and Prato, which is for climbers only, so stay on the road below Trafoi. The hairpins above Franzenshöhe are slow and blind. Brake before the bend, not in it; descending faster and safer covers the rest.
• Make it a loop. The other two sides are just as good. Descend to Bormio and you can climb back the same way, or cross the Umbrail into Switzerland and drop to Santa Maria in Val Müstair, then return to Prato through the valley. Our Stelvio from Bormio guide covers the southern side.

Ride it in Moveee Indoor

The route on this page is the real road from Prato to the pass, with its height at every point. In Moveee Indoor your smart trainer reproduces that gradient as you ride: the valley drags, the forest hairpins bite, and the last six kilometres feel as long as they are. The world around you is built from the map of the actual place. It is the best preparation for the real thing we know of, because it teaches you what two hours of climbing feels like before you are halfway up a mountain finding out.

Ride it once early in your build to get a baseline time, then again a few weeks before your trip. If your second ride is faster at the same heart rate, the training is working. If it isn't, why you stopped getting faster is worth a read. Prefer your own device? Download the GPX above and load it into any app that rides GPX files.

The short version

25 km, 1,850 m, 48 numbered hairpins counting down to 2,757 m. Ride the valley gently, take the forest at a steady effort, and expect less power above Franzenshöhe. Go early, take a jacket for the descent, and ride it on the trainer first so the mountain holds no surprises.