From the bridge over the Somiedo River in La Riera, at 1,611 ft (491 m), to the top of Puerto de San Lorenzo at 4,416 ft (1,346 m), it’s 6.2 miles (9.9 km) at an average 8.6%: 2,805 ft (855 m) of climbing on the AS-265, the road linking the Somiedo and Teverga valleys. Altimetrias.net gives 9.91 km and 855 m; Climbfinder gives 9.9 km and 862 m, with the worst 100 m (330 ft) at 16%.
What the climb is like
It’s brutal from the first meter. Right after crossing the bridge at La Riera come three kilometers (nearly 2 miles) averaging over 10.5%, with 16% ramps, and the hairpins begin: Climbfinder counts 13 on the whole climb. Then the grade eases a little, only to stiffen again in a second and third block before the top. In all, there are about six very demanding kilometers (3.7 miles) split into three blocks, with some relief between them.
The road was resurfaced a few years ago: about 20 ft (6 m) wide, good pavement and signage. There’s little shade and almost no traffic, and the views over the Somiedo valley are some of the best in Asturias.
Where you are
Somiedo is a natural park and biosphere reserve, home to the largest brown bear population on the Iberian Peninsula. Other well-known climbs start from the same valley, such as La Farrapona and the Puerto de Somiedo, making it a perfect area to spend several days climbing.
When to go, water and traffic
May to October. In winter, snow and ice are common near the top, and fog is frequent in spring and fall. There are a few fountains in the villages you pass through, but leave Pola de Somiedo with full bottles and ask if in doubt. Traffic is very light.
What gearing to use
At 3 W/kg (watts per kilo of body weight) and 159 lb (72 kg), you’ll average about 6.2 mph (10 km/h): on a 34x30 you’ll pedal around 72 rpm. On the first three kilometers, above 10%, your cadence drops a lot, so a 34x32 is not overkill. Run the numbers in the gear calculator.
Tips
- Warm up before you reach La Riera: there are no easy opening kilometers.
- Use the gentler stretches between the hard blocks to drink and eat.
- If you descend to Teverga, remember that side saves its hardest part for the end, in case you have to come back over it.
Frequently asked questions
How long does it take to climb Puerto de San Lorenzo?
A 159 lb (72 kg) rider on a 21 lb (9.5 kg) bike takes about 58 min at 3 W/kg (216 W), 1 h 08 min at 2.5 W/kg and 44 min at 4 W/kg. Work out your own time with your weight and power in the calculator on this page.
Which side of San Lorenzo is harder?
They're very close. The Somiedo side (La Riera) spreads its difficulty over three blocks and opens with three kilometers above 10%; the Teverga side is steadier and saves the hard part for the last five kilometers.
What gearing do I need for San Lorenzo?
A 34x30 or 34x32. At 3 W/kg you'll average about 6.2 mph (10 km/h), but you'll go much slower on the opening ramps above 10%.