Montseny mountains are really close to Barcelona. You can reach them in about 50 km. Once in Sant Celoni (the starting point of many of the climbs) then you can choose several roads:
1) Turó de l’Home. This is the king climb in Montseny. Reaching 1700 mts height, the climb is 25 km long with very steep parts, specially arriving to the summit.
2) Santa fe del Montseny. Spectacular road also 25 km long reaching 1300 mts. Specially on working days there is no traffic at all, perfect for cycling!
3) Coll Formic. One of my personal favourites. A scenic, sunny road, you can climb it even in winter, reaching 1145 mts. Mild climb most of the 26 km, but last 9 km are a bit steeper. A real first category climb.
4) Coll de Ravell. Between Montseny and Guilleries, this is also one of the solitaire roads you can ride when touching Montseny mountains. Really worth!
No doubt that Turó de l’Home is one of the highlights if you are in Barcelona and you are into cycling. A real challenge!!