There used to be a chap who commuted by unicyle through central Edinburgh - he cycled up the Mound, a hill linking the New and Old towns.

Given how hilly Edinburgh is and how popular cycling is here (and getting noticeably more popular each year) I don't think having hills is really an excuse for nobody cycling.

[Need I also point out how unpredictably miserable the weather can be here...]

Best by US standards. It's hardly mass adoption compared to the Netherlands is it?