Originally Posted by
Street rider
Very much false. An American bb, by definition, is a Mid sized bearing inside of a cup to fit the frame. So if he switches, he still has to have an American bb, meaning Mid's in cups pressed into the frame. You just sorta canceled out your own statements/logic in the parts I highlighted...
Because you are correct (an Amer BB is a Mid Bearing w/in a cup), he can simply order/purchase his crankset and a Mid BB and simply re-use the cups. Very rarely have I seen the need to replace cups when maintaining/upgrading Amer BB's. However, I frequently see the need to replace/upgrade the bearing set during the same process.