Was there not a bike program on the telly some time back ... Where the chap had something of the same delmer ... Think he rolled it up in a small plastic bag and with a bit of string pushed up the handle bar and then put back the end weight ...
i use somethig called a "pacsafe". it goes over your head and is a bit like a holster. it has enclosed steel wire so cannot be cut off you by scumbags.after my mate lost his bum -bag containg his life i dont put valuables in mine any more.
i always take a large wad on trips and have had to bail out the other guys on a few occations.it feels compfy and safe.