There was a interesting guest article on TucsonVelo blog about a a rider's perspective on cycling in Tucson as well as London.
Naturally, London (Headquarters of Brompton) is so much denser than Tucson and you have to be very aware and proficient to get about safely.
Tucson, in contrast, is much more sparse. The biking lanes are very wide and generous. Unfortunately, the roads are also crap.
Please take a look at the original post: