have looked into this since and found that you fold approx 2 inches of your mainline over inside stiff rig tube above your lead so when the fish picks up your bait it feels the no2 elastic then when it bolts it is connected directly to the mainline the idea being that the no2 elastic makes the bait hard to eject once the carp feels the pri ck of the hook.had the same concerns as you but have seen the rig on a dvd called welly wackers.may work.