the bit with the hole in it goes around your axle between the nut and the dropout, then the long bit goes over the end of the dropout with the threaded bit going down the center of your dropout. then when you tighten the nut on the end of the tensioner the wheel moves backwards thus tightening your chain to the right tension before you do up the wheel nuts.
the bit with the hole in it goes around your axle between the nut and the dropout, then the long bit goes over the end of the dropout with the threaded bit going down the center of your dropout. then when you tighten the nut on the end of the tensioner the wheel moves backwards thus tightening your chain to the right tension before you do up the wheel nuts.