Decent (Enough) Short-Duration Locks

Those Defcon locks look like they're good fun & compact.
I think I'll check those out.
Cheers

As an additional back up measure when using a lock you aren't fully happy with, why not unship the chain as well? This will give you an extra bit of time if someone does try to jump and pedal away-just remember to put it back on before you try to pedal off as well though!

You could try one of these.

http://www.amazon.co.uk/Targus-Defcon-Anti-Theft-System-PA400E/dp/B002EA...

I use it along with a fairly light weight coil/combination lock. It's loud enough to make you aware somebody is messing with your bike. It has both motion sensor and cable tamper. It'll sit in a jersey pocket along with your gels or whatever.

I have a Kryptonite coiled cable lock - it's 600grams, but can be mounted on the seatpost which is a reasonably out-of-the-way place for it. It's strong enough to resist casual impact attacks but as you say, if someone happens to have bolt cutters with them there's not much you can do.

I bought a retractable wire lock for my kids to use at primary school but it was prone to sticking and the plastic case doesn't look very robust; one sharp tug and it may fall apart.

I would suggest a coil cable combination lock, you can wind it round the seat post or head tube when not in use:

http://www.halfords.com/cycling/accessories/locks/halfords-resettable-co...
http://www.wiggle.co.uk/abus-numero-1300-cable-bike-lock/

Anyone thinking that their bike won't get nicked in rural areas is kidding themselves, I have heard about a number of bikes being nicked after being left for just a few minutes. And bear in mind that any insurance will be invalidated if you didn't bother locking it to something.

How upset will you be if it disappears? If you value it then lock it up.

Unfortunately the garage forecourt scenario is one where bikes often are stolen. I'm yet to be that unlucky, but I did once come back to my bike after leaving it for about a minute to find the seatpost toolbag open. Multitool, patches and spare tube taken, some people are real pikeys!

The amazing thing is, I would have been in sight of it, I just had my back to it to use a cash machine.

It would be nice to see some more integrated solutions for this sort of use. I vaguely remember some design that had the cable integrated into the seatpost, which seems quite a good idea.

I wrestled with the same dilemma a few years back, and then gave in and decided not to carry a lock at all. I frequently stop in village shops and, in the small villages you mostly encounter in the countryside, there's nothing to worry about from a theft point of view. Leave the bike somewhere near the door, pop in and out and you're done. In busier areas, I stop on garage forecourts where there's big windows (so the attendant can see all the pumps) and lots of CCTV. Again, low theft risk for those reasons. Ultimately, I didn't want to carry anything more than I really needed, and sticking to the plans above I feel pretty comfortable that my bike won't go anywhere without me!

On the summerbike I have a thin coiled cable combination lock, too. Folded up, its the size of two matchboxes and does not weigh much at all. Only good for stopping the occasional drunk jerk, though. But it's only for café stops and such. The bike has no theft protection for the wheels or saddle, but then the bike and its components are so old and beaten up they probably are of no interest to a regular thief.
Got a heavy-duty folding lock on my winter bike, which one actually might be of more interest to a bike thief. I don't really use the lock that often, usually my winter rides are not long enough to require a pause mid ride. I can't say the weight of the lock have bothered me much the times I've taken the lock with me, but then the winter bike is a chunky 29er that is somewhat heavy on its own already. The lock rides in a pocket that attaches to and reserves for it self a pair of bottle cage bosses.

You might want to look into replacing the quick release skewers on the wheels with lockable ones. I have no experience with such, but the idea seems reasonable.

For short stops I use a thin cable (combination lock) 'cafe lock'. Easily fits in a pocket or seat pack. If I'm stopping for longer and the bike's out of sight, with a greater risk of theft, I've devised a way of carrying a mini U lock (Abus or Kryptonite do them). I use one of the strap-on (through the seat rails) seat packs, wedge the shackle between the seat and the pack, with the barrel in the seat pack. I put the U lock through the spokes and one of the seat stays (works OK with the average town bike stand); cafe lock to stop someone taking off the front wheel. I recently had a short ride back from a pub and, to save time, just shoved the shackle in a jersey pocket. Didn't really notice it as much as I thought. The U lock is a bit of weight, but then rather that than having the bike nicked.

I use one of these. the cables and the lock fit in a jersey, or the cables can be wound around the steerer tube, or seat post.

https://www.kryptonitelock.com/Pages/ProductInformation.aspx?PNumber=000440

Certainly NOT secure for overnight locking in the Bronx!