Ok, so bike locks can be worked over easily - I've seen that from each bike-lock related post in the last week...
but assuming your bike is attached to a secure structure... (not a sign post)
and that you haven't attached your lock to a part of the bike that comes off (wheels)
and the thief must either:
defeat the lock
or walk away
whats the most oft used method of defeating the lock?
Is it overcoming the locking mechanism? Or the physical structure of the lock itself?
Why aren't there bike alarms on sale and in use?
My point to this post is to discover the greatest weakness in locks (specifically higher end locks) and to come up with ideas for better ones.