Bottom bracket too tight to screw in by hand I'm trying to install a new bottom bracket (BB-UN55, BSA) into a new aluminum frame. Trying to screw them in by hand only allows me to go a few threads deep. On the non-drive side cup there is some thread locker that could explain the tightness a bit, but on the drive side, there doesn't seem anything that should block screwing it in by hand. I've checked the orientation of the threads on the shell and BB (CCW on drive side, CW on non-drive side), and the width of the bottom bracket (68mm).

Is this a clear case of needing to have the shell threads chased? Or could I proceed softly with a wrench without much risk of damaging the shell threads? What else could I check to make sure the frame and BB are compatible?
If one side screws in without problems, and you've verified the thread orientation, then it's not a compatibility problem. ( http://sheldonbrown.com/bbsize.html - scroll down to "bottom bracket threading".)

Trying to gently tighten it with a wrench should be fine. If you encounter abnormal resistance, then you should start thinking about taking it to a shop for chasing.