I know nothing is thief proof, but some systems are more of a deterrent than others. Looking for recommendations for good systems. Perhaps more importantly I'd like to hear about systems found to be insecure (i.e. can be broken with a bic pen level of technology).
And, does anyone use a special seat bolt (the one right under the seat that is used to lock fore-aft)? I know a keyed seat post bolt can be sidestepped simply removing the seat top - is that a common target, just the top of the seat without the post and platform?