The Hague (and the whole of the Netherlands) is flat, which makes cycling so easy and fast. That it's a free form of transportation is also pretty attractive. I got my bike by the end of the first week I arrived, from a lovely Moroccan man, Mr Hassam, who speaks French, Dutch and Moroccan Arabic. He sells bikes much cheaper (30-50 euros) than the market price (75-100 euros), and I think he's been getting many clients from ISS!
The generous provision of bicycle lanes is incredible! On almost all tar roads there's a small red lane on the right-most lane for bicycles, and cars respect cyclists here. Well, the first priority is pedestrians (I have yet to experience a driver swearing at a pedestrian, because it's always the pedestrian's right of way!), then cyclists, and then cars. I remember reading an article that somewhere that described cars as 'a source of amusement in The Hague', haha.
There are rules of course, like having to attach white lights to the front of the bicycle and a red light at the back. There are battery-powered lights that you switch on only at night, and also lights that run on the kinetic energy of the front wheel (that's the one I have, and it makes such a fun revving sound when I'm cycling, but when it rains the connection isn't so good and it starts to blink.). If both lights fail you, or you prefer to decorate yourself, you can also wear the lights instead (clips onto your shirt or bag). Lights are important, because you could be fined 3o or 40 euros if you're caught cycling at night without lights!
The most common type of brakes here are the reverse brakes, which means you cycle backwards in order to brake! Of course, there's also handbrakes (but probably not authentically Dutch, haha) but the footbrake isn't so difficult to get used to once you try! It's also convenient if you're carrying a shopping bag full of groceries with one hand and steering with the other (common, common sight).
Another amazing thing I found out is that Dutch towns are pretty much all connected by small roads that you can cycle on. So even though Leiden is 10min away by train (which seems quite far), I see signs that it's only 20km away, which is totally bike-able! In an hour or maybe less. Although you'd have to budget a lot of time for reaching the town then. Heh.