you might be able to find one of the "other" type of seat binders although they are a bit hard to find now. there are even campagnolo ones. (i used to see them on cinelli steel frames if i remember correctly) instead of a key they have splines that wedge themselves in all the way around. there is also an allen key socket on the other side so you can hold it in place (with a second allen key) while you tighten/loosen.. it is very important to grease the threads and the inside of the hole in the frame where the bolt part moves because the lug angles as you tighten it. often it is not a very perfect fit.
or you could just get a keyed type one like you have and just use another allen key on the other side to stop it moving. (i assume the one you have now has no allen key socket on the other side, most of them do now)
Last edited by neutron7; 09-08-04 at 08:01 PM.