Should I ride my first fixie back from the shop (in London)?

Oh, Ed, you're crazy if you think London isn't dangerous! Try riding in NYC and then tell people it's not dangerous here. It's freakin' insane crazy time riding in London! Of course, you get used to it and someday, years later, learn how to navigate without constantly looking at the A-Z.

You should try riding in Paris! Road signs don't mean anything, zebra crossings may aswell not be there, using your indicator is frowned upon and going through redlights and flashing green men is the norm!

Complete free for all

Loved it though :-)