Cycling in Barcelona at night might be an issue if you don’t know the right places to ride.
Here we make some suggestions, in order you can cycle safely in the dark hours.
1) The best place to ride at night is the Formula 1 track in Montmeló town. Not away from the city, you can get it by train. The Formula 1 track is open just tuesdays and thursdays from 18,30 to 21,00. The track is not fully lighted, so you will need to have a good light. The length of the track is 5 km so you can make some loops and test yourself. The loop includes an couple of nice climbs.
A ticket for 1 day costs 5 euros. You have to bring your own bike.
More information here:
2) There is a bike lane along river Besos (from Sant Adrià del Besos to Montcada i Reixach) 7 km long which is lighted, also very safe, as there are no cars, just walkers, hikers, some skates and dogs (watch out with unleashed dogs). It is a very good and safe place to cycle in the dark in Barcelona.
3) There is a very nice road to cycle at night which we call “Dummidrome” (Tontódromo). It is the road between Cerdanyola del Vallès and Sant Cugat del Valles. Very easy to get from Barcelona. Wide road with 2 lanes every direction, fully lighted which is also a safe place to cycle at night around Barcelona. The route can be longer including the road to the University (Universitat Autònoma de Barcelona). This road is used in the very popular Cerdanyola Duathlon, late march.
4) Since the new airport Terminal (T1) was opened, there is a large road from Barcelona to the airport which is also very good for cycling. 2-3 lanes each direction, totally safe. Open traffic but very scarce. To get that part, the best way is to go through the industrial area of Zona Franca.
These are my personal suggestions to cycle at night in and around Barcelona. Probably there are many other options, but these are the ones I would recommend.
Enjoy and keep safe!