I did some research on this one day, and what really got me thinking was - if there are 370,000 bikes stolen every year (probably much more than that, because most thefts go unreported), and about 6,000,000 people use bikes to commute, then about 1-2 bikes in 20 are stolen. This seems like a really large proportion, which leads to the question - who buys those bikes? I mean, most of them must be stolen from law-abiding citizens and then bought by (slightly gullible) law-abiding citizens somewhere else.
This led me to think that bike theft, which impacts almost everyone (apparently a majority of commuters will have their bike stolen at some point), is actually one of the few problems which could be solved by legislation. If everyone registered their bike (like they do with cars), and then reported thefts, and then checked the database when buying used gear, then the market for stolen bikes would shrink immensely. And since everyone is already paying 30pounds+ for a lock at the moment, I don't think anyone would mind a 20 quid registration fee if it would really make their bike safer. I know that we already have bike registers in place, but they are non-compulsory and hardly anyone uses them, and this seems to be one of those things which only work if everyone's in. That's just my 2p.
As for not getting your bike stolen in the current situation - there doesn't seem to be any hard research available, but anecdotal evidence points out that there are two main types of bike thief:
- The unprofessional (and this seems to be the majority), most likely looking for a quick money fix (since bikes are so easy to liquidate), who'll most likely be going around town with cable cutters and looking for easy catches
- The professional, who'll have all the tools he needs (and a 50 pound portable angle grinder with a cutting blade will beat any lock), will keep an eye out for the really good bikes and steal them
Since no lock known to man will stand to a couple minutes with an angle grinder (and do not count on passers-by - a person in high-vis can do whatever they want in the middle of the city centre and no-one will bat an eye), there is no way you can protect your bike when it's outside from the professional thief. Except maybe for not using a fancy bike when running errands around town.
As for the majority of thiefs, a short walk around town will show you that there are a lot (and I mean A LOT) really good bikes fixed to remotely located racks with cheap cable locks, so a good U-lock to secure your back wheel & frame, and then a cable to secure the front wheel (maybe the saddle as well), will probably be enough to disencourage the opportunist thief. As someone elsewhere on the internet put it - you don't have to run faster than the bear, you only need to run faster than the friend who's running with you. The surest (although maybe slightly unethical) way to secure your bike is to find a bike which looks better than yours and is not secured very well, and then lock your not-as-fancy bike next to it with a better lock.