To answer 3 questions.
The familiar Kryptonite locks could be broken by leverage attacks in a matter of seconds. Their strength comes from their crystalline compound structure. THis means, however, that if enough pressure was applied on their butt end (especially after a dose of quick-freeze spray), they'd shatter instantly. They have a new lock
the Evolution 3000, which they're only selling in Europe. It claims to prevent this, but I mean that's a lot of money for the gamble.
The lock that I use is a an armored cable (for
picture click here). They are flexible so can be used to wrap around a greater variety of posts than the kryptonites. They can be gotten all over the place, but as you see Argos has them for ten pounds. 60 for a kryptonite, 10 for an armored cable: you decide!
When I lived in Manhattan, I bought some armored cables back, and I can say that for 6 years I kept my bike locked on the mean streets of Gotham with these cables and they were never compromised, the bike remains in my possession.
2) I'm a city biker, not a long haul one. I'd give tremendous respect to Sam, who is much more skilled in the latter. I don't own a car here in England, so I use my bike to get to work and to shop. Yes, it's true that in the winter, it can be a little uninspiring to bike, but then I use the bus.
3) What you probably saw in Mexico was a guy with a folding bike. It's a small whell bike that can be folded in to the size of a carry on suitcase. They are very popular here, especially among commuters. If you go to Euston or King's Cross in London at the rush hours, you'll see tons of people with them. THey take the train into the city and bike their way to work. Prices vary. They wouldn't work for me, since my work is about 2 kilometers away, but for situations like I described, they are fabulous. Also, I'd bet that if you want to do day trips to cities. Then taking a train with one of the bikes would be a great way to get around the city.