Question about installing a Shimano UN-72 bottom bracket. The instructions on the Park web site say to snug the fixed flange, then tighten to spec the removeable ring, and that "By securing removable ring, you are securing the other side at the same time. Removable ring pushes against fixed flange.". OK, but my UN-72 BB does not have a fixed flange, but just a fixed ring with no flange (the removeable side has the flange). So should I just reverse the instructions and snug the removeable flange first, then tighten hard the fixed ring?
Question about installing a Shimano UN-72 bottom bracket. The instructions on the Park web site say to snug the fixed flange, then tighten to spec the removeable ring, and that "By securing removable ring, you are securing the other side at the same time. Removable ring pushes against fixed flange.". OK, but my UN-72 BB does not have a fixed flange, but just a fixed ring with no flange (the removeable side has the flange). So should I just reverse the instructions and snug the removeable flange first, then tighten hard the fixed ring?
There is no ring on a UN-72. There should be a fixed cup that goes on the drive side of the bike. If your BB is English this should be left-hand thread and should not go into the other side of the shell. You thread that in til it stops and make it tight. Then you take the threaded piece without the flange (right hand thread on an English BB) and torque it to spec on the other side.
The only way you could mix them up is if the BB shell is Italian.
The side with the flange should absolutely be installed and tightened first, otherwise it won't go in all the way and the BB will come loose, guaranteed.
