Can anyone recommend a lock that can be carried in a ruck sack that is at least vaguely effective?

Bike will be in a secure shed at work anyway but still rather use a decent lock,..

can you leave the lock in the shed?

I carry an abus granite but it weighs a ton – I carry it for 4 miles hooked over my handlebars and its OK, but I wouldnt want it on my back.

A good shackle lock – I use motorcycle stuff. Look for a hardened steel shackle that both ends lock into the bar, 16mm + thickness. Expect to spend around £100

Abus granit?

Get a BFO lock and leave it in the shed. You’ll need another with you or you can’t stop on the way to/from work.

I’ve always found a frame-mounted D-lock to be the easiest to carry.

APF

I always fancied one of these as they seemed a well thought out idea. Dont know how strong they are but you’ll be ‘down wit kids’

http://www.hiplok.com/