The closest hostel to Centralstationen has clean rooms, friendly staff, free bike hire and excellent facilities, including sauna, laundry and kitchen (with a free stash of pasta). En suite private rooms are also available. Bonus for female guests: there are four- and eight-bed female-only dorms if you prefer, and you can borrow a hairdryer from reception.
The hostel also has six-bed apartments (from 1800kr) for rent, with bunks, their own kitchens and bathrooms – a great option if you're in town for a while and want to cook your own meals.