I’d like a small, lightweight lock that allows me to stop for a coffee when I’m out riding. Something I can place in a jersey pocket would be great.

What would you recommend?

Hiplock Z lock could be an option.

I use https://www.hiplok.com/product-category/security-ties/

Yes, you can cut through it with wore cutters or a really good pair of scissors.  But I always make sure I can see my bike and get to it quickly – this does the job for me.

If you want something more secure then I’d wait for other suggestions!!!

Si

If you just want a deterrent to stop a casual thief running off with your bike, these are OK:
https://www.hiplok.com/product/zlok1/
It’s basically a metal zip tie. Easy to stick in a pocket or loop around saddle rails.
Of course it won’t stop anyone serious for more than a few seconds.

Ottolock is OK too. Bit bulkier that the smaller zip tie ones, and quite pricey, but it looks serious enough to dissuade anyone that doesn’t have decent tools on them.

I bought this off Amazon and seems decent quality https://www.amazon.co.uk/gp/product/B00KXWSUDY/ref=ppx_yo_dt_b_asin_title_o00_s01?ie=UTF8&psc=1 A bit more substantial than a zlok and a lot longer

This is really light, and would be quick to break, but it might do what you need.
https://www.planetx.co.uk/i/q/BLJOIMRELO/jobsworth-ristretto-retractable-cafe-lock
I often carry one for very quick stops.

You can get alarmed ones like that thin cable one. If you get two alarmed one then they only have to cut one to get a sharp piercing sound-shock which could be enough to save the day.

Also, I just bought some security QR skewers to deter opportunist wheel-scrotes.

This is the most pocketable U lock I’ve ever had.

https://www.ortre.com/store/p3/BI5_U_Lock_-_Original.html

I use one of those Center Parcs cable locks as a front wheel lock on commutes and for brief visits to local shop away from precinct.

However, I used one for a visit to precinct ~5 years ago and within a few minutes of entering Sainsbury’s, some scrote cycled up on a kids bike and snipped the cable and off he went with the bike.

i’ve got one of the Planet-x ones but only if it’s in sight, or it’s in a group, such as a club ride (where someone else’s will be unlocked and easier to nick or just better if they know what they’re after)

If alone, it’s only to deter someone long enough that I can get out there anyway. I might also drop the chain into bottom or onto top so if anyone hopped on they can’t immediately ride away, or even drop it onto the BB at the front to make it into a foot race. Pointless probably but makes me feel better.

Padlock through the chairing will stop someone just riding off on your bike

^ Neat idea, never thought of that. Likelihood of mashing the frame though? Or long padlock through chainring and around lower seat-tube, or D-S chainstay??

What about those motorcycle disc-rotor locks/alarms? Could be made useful for bicycles?

What about those motorcycle disc-rotor locks/alarms? Could be made useful for bicycles?

Pretty heavy, and not something I’d like in my back pocket (uncomfortable + not ideal in the case of a crash).

Disk locks are pretty useless as you can pick up a 9kg road bike pretty easily and walk off with it. I use a Z-Lock combo and seems to be a good compromise. I’d disagree that you could cut through it with a pair os scissors or cable cutters…the plastic strap has a metal band inside so a good pair of tin snips or something would be needed so not the kind of tool that the casual bike thief would be carrying around in their pocket…and its the casual bike thief you’re protecting against. A determined thief that had targeted your bike specifically would be adequately tooled up to get through any lock you might be using.

I’ve actually got two z-locks as they’re not very long so hard to lock to something, so lock one around the frame and loop the second around an object. they are light enough to not be noticeable on the bike and small enough to have in your back jersey pockets and not cause any uncomfortable digging into the back situation.

Some locks are easier than others to pick.
And lock picking is more subtle than a cordless grinder.

This is what I use when I pop to the shops –
https://www.sportsdirect.com/everlast-gym-lock-769157#colcode=76915790

..on the disc like Malvern’s pic. Depends where and for how long you’re leaving it I suppose. My Tripster hasn’t been nicked from outside Tescos anyway.

I really like my hiplok belt thing (https://www.amazon.co.uk/dp/B016186DNC/ref=pe_3187911_189395841_TE_dp_1) for quick blasts into town. Not up to the job of securing a bike left at the railway station all day and just a little too big for a cafe stop on a ride I think. If it was a cafe trip that I was riding to where the main element was the cafe not the ride it would be just the ticket if that makes sense!

I use the Hiplock things.

Currently on sale at Sportspursuit: https://www.sportpursuit.com/sales/hiplok-dec19

+1 for Ottolock. It’s a bit pricey but a much more substantial deterent than a piece of wire or cable tie, and we are talking deterent here, nothing will stop a well equiped determined thief. You just have to make your bike less stealable than the others unfortunately. Rolls up nice ‘n’ neat to stuff in your riding pack.