With currently 29 cycle routes all around Leiden, there are plenty of options for outdoor enthusiasts. In total, 26 bike rides and 3 bicycle tours are waiting to be explored!
Leiden is a university city about 20km north of The Hague and about 10km away from Duinrell by bike. The route from Duinrell is a great example of Dutch bike infrastructure, with most of the route being on segregated cycle paths away from the road. The points at which you have to share the road are generally pretty quiet and you can expect to see very few cars.