No idea about Berlin, but I used to live in London, just on the south side of Tower Bridge.

http://www.bhf.org.uk/get-involved/e...bike-ride.aspx

How about London to Brighton? There are other London to rides but this is the biggie. You come back on the train.

I used to ride to play tennis/squash as it was quicker than driving and I could have a few beers. Depends on what you are trying to do.