Before renting a bike from the "Oso goloso" rental shop in Proaza, you should know the following: the gearshift on the mountain bikes (without mudguards, bell, or luggage rack) is absurdly intentionally locked so that, out of a hypothetical 18 gears, you can only use 4 in the middle range (so the chain doesn't come off, hahaha). After you pay and sign, they'll explain this to you. However, this is completely unsuitable for riding the Bear Trail, especially the rather steep eastern variant with its very poor surface. Even with good fitness, you'll often have to dismount. Apparently, there's another rental shop in Proaza...