The issue of bicycle locks is complicated by the need to defeat your own lock if for example as in my case, the combination no longer works (happened to me once before when 1515 became 2515 but I got that by trial and error - caused by knocking the switch that lets you change combination). Anyway, a hacksaw was USELESS for my cheap £5 lock which was constructed of many steel cables woven together. However, after two chops with a pair of big bolt croppers, the lock yeilded and my bike was free. Whilst this was pleasing at the time, and would be in a similar situation in the future, I suppose you've got to balance it against other people getting in.
Would a D lock be so susceptible to bolt croppers? I've heard of D locks being defeated with a biro (flawed key design)! I was wondering what ways different locks were defeatable. For example, there are £100 kryptonite chain-based locks available - which is the weakest link (the chain or the lock) and what would it take to break it? Can anyone advise which locks are good against and which are weak against different methods of breakage?
If you couldn't get into to your own fancy expensive lock, would you have to pay the fire brigade to use the jaws of life? And how much would that cost?
Maybe at the end of this discussion, a sticky could be posted advising which combination of locks to use.