22 km of greenway along the old mining railway, with more than 30 tunnels, two gorges and a real bear right beside the trail. Everything you need, in a single guide.
From the free enclosure viewpoint, during the cooler hours of the day.
Along the old mining railway, with an average gradient of 1.5% and no cars.
Carved through the rock for the train and lit today with solar lamps.
Molina lives in the Fernanchín enclosure, right beside the trail near Buyera.
From Entrago (Teverga) to Tuñón (Santo Adriano), plus the Quirós branch.
Asturias' most famous greenway: 22 km laid over the trackbed of the old mining railway (1884-1963), with a firm compacted surface, more than 30 tunnels and not a single climb to fear. The train once carried coal down; today the trail carries visitors up into the valley of the bear.
40 km from Oviedo (45 minutes via the A-63 and the AS-228), crossing Teverga, Proaza, Santo Adriano and Quirós.
These valleys are Cantabrian brown bear country, and since 1996 the trail has passed a bear enclosure with a real bear: Molina.
Choose how to do it
18 km gently downhill from Entrago, 2-3 hours with stops and the return transfer included with your rental.
From the 20-minute stroll to the bear enclosure to the full 22 km traverse: choose how much trail to walk.
A firm compacted surface, zero cars and equipment from 8-9 months old: baby seat, trailer or tag-along.
A shaded trail, four fountains along the way and dog trailers up to 30 kg if you go on wheels.
Three arms in a Y shape
The first section to open (1995): the Peñas Juntas gorge, the railway tunnels and the bear enclosure.
The long tunnels and Valdecerezales: the stretch of the Teverga valley that rewards every pedal stroke.
22 km for the main route, about 30 for the full network and up to 60 if you ride everything out and back.
The Y-shaped layout with access points, free car parks and highlights, ready to check.
Choose your size and extras, with free cancellation up to 24 hours before
Polígono de Pradacón, Nave 1, with free parking right next door
Railway tunnels, gorges and Molina's enclosure halfway along
The transfer back from Buyera is included with your rental
What sets it apart
At kilometre 19, next to the Buyera rest area, the trail passes the Fernanchín bear enclosure: 40,000 m² of hillside that is home to Molina, a bear rescued in 2013. Before her it housed Paca and Tola, symbols of Cantabrian bear conservation since 1996.
And if you are after wild bears, Somiedo is 45 minutes away over the San Lorenzo pass.
The setting
the way
The heart of the route (km 14): the village centre 200 m from the trail, a mid-ride vermouth and the Bear House.
Entrago and San Martín: the start of the bike plan, the Prehistory Park and the end-of-ride restaurants.
Tuñón and its pre-Romanesque church from the year 891, 300 metres from the trail. The gem nobody expects.
Santa Marina and Bárzana: the quiet reward of the Valdemurio reservoir branch.
Logistics sorted
The practical side in four cards: how to get there, where to park before it fills up, where to sleep right by the trail and where to sit down to eat at the end of the ride. May, June and September are the sweet-spot months.
From Oviedo, 40 km (45 min) via the A-63 and the AS-228. By bus, the Oviedo–San Martín line.
Free: Entrago ~60 spaces, Tuñón ~40 and Proaza ~20. In summer they fill up before 10:00.
Rural hotels and apartments in Teverga, Proaza and Quirós, right by the trail.
From the vermouth in Proaza to the end-of-ride menus in San Martín and Entrago.
Real prices, 2026 season
A serviced mountain bike with smooth gears, for ages 12 and up. What most people choose.
For the full out-and-back, the Quirós branch or groups with mixed fitness levels.
Seats, trailers, tag-alongs and kids' sizes 16", 20" and 24". From 8-9 months old.
The history
The railway that shaped it opened in 1884, on a 750 mm narrow gauge, to carry coal from Teverga and Quirós down to Trubia. It closed in 1963, and after three decades of neglect the valley reclaimed it in stages: the first stretch of greenway opened in May 1995. That is why the trail has no climbs: no train could have managed them.
Your questions answered
Yes. The official name of the greenway is Senda del Oso, and Ruta del Oso is what many people call it. Same trail, same sections, same bears.
The trail is free, so is the viewpoint over the bear enclosure, and it is open all year round. If you ride it by bike, rental costs €28 for the full day per adult, with helmet, insurance and the return transfer included.
It is their ideal terrain: a firm compacted surface, almost flat and completely car-free. There is equipment from 8-9 months old (baby seat, trailer, tag-along) and the star plan is reaching the enclosure of Molina the bear.
Yes: Molina, a rescued bear, lives in the Fernanchín enclosure next to the Buyera rest area. You can see her from the free trailside viewpoint, with a 70% chance during the cooler hours of the day.
By bike, the usual ride takes 2-3 hours with stops. On foot, pick your section: from the Buyera car park to the enclosure is a 20-minute walk; the full route takes 5-6 hours.
By bike, the classic plan starts in Entrago: 18 km gently downhill to Buyera with tunnels, gorges and the bear enclosure, and the return transfer included with your rental.
The next step
Prices from €15, helmet and insurance included, and a free return transfer. Free cancellation up to 24 hours before — and if it rains, on the day itself. On holiday weekends and in July and August the bikes go fast.
Seasonal guides
May, June and September are the sweet-spot months. The detail, month by month, with the valley's weather.
The honest list: a thin layer for the tunnels, water, and little else. Anything extra just weighs you down.
Two days to do it all without rushing: trail, bear, pre-Romanesque art and a table waiting.
Ruta del OsoSenda del Oso greenway22 km of car-free pathMore than 30 tunnelsMolina the bearTeverga · Proaza · Santo Adriano · QuirósAsturias, Spain Ruta del OsoSenda del Oso greenway22 km of car-free pathMore than 30 tunnelsMolina the bearTeverga · Proaza · Santo Adriano · QuirósAsturias, Spain Ruta del OsoSenda del Oso greenway22 km of car-free pathMore than 30 tunnelsMolina the bearTeverga · Proaza · Santo Adriano · QuirósAsturias, Spain Ruta del OsoSenda del Oso greenway22 km of car-free pathMore than 30 tunnelsMolina the bearTeverga · Proaza · Santo Adriano · QuirósAsturias, Spain 
