On my old blaster I couldnt get my chain to pop off even with slack, that damn chain guide on the bottom kept mine on. On the blaster I got now my chain was extremely tight, but hell I cant get the top bolt off for the carrier to loosen the chain. Someone tried loosening it with the bolts still in and twisted the bolt on the chain tighteners.
well i am 250lbs and with about 1" slack, the chain never gets tight when I sit on the back. with 2" of slack, my chain pops off.