What you need is a thick but hollow motorcycle lock..

Big chains are SOOOO heavy and rattle about furiously. I cant think of anything worse to carry on an Overland trip.

I used a motrax Kabul lock.

Motrax Kaybul Stainless - 1.2M (Motorcycle Cable Lock))

It looks HARDCORE but infact its hollow and doesnt rattle about at all. Its not even that heavy. It fitted nicely around my rear rack.

I think its more than enough to deter all but the most determined thief. And rememeber, if they want it, they will have it.. No matter what lock you use.

Your link is dead

http://www.sounddistribution.co.uk/images/KBSS12.jpg
Motrax Kaybul Stainless 1.2M

Hmmm.