In Copenhagen, 37% everyone working or studying use a bicycle to commute. So, when all these bikes are out on the roads, it can get quite busy. Morning rush hour occurs around 7:00, and evening rush hour occurs around 16:30. Cycling in rush hour can be a bit intimidating because of all the bikes, however, you just have to follow what everyone is doing, and then its not too bad. Of course a good understanding of the rules, and how to signal is also important. Here is a video of morning rush hour to give you taste of what it is like.
If you find yourself in the middle of rush hour, and it is too much remember that you can always walk your bike on the side walk instead of cycling in the traffic.