Originally Posted by wildjim
Usually it's the right side(chain side) that is factory installed and very tight. The left side usually has a reverse threaded Lock Ring to remove(Lockring Wrench) then the cup will unscrew easily with a Spanner Wrench. Also note the Spindle orientation as it maybe and bit longer on the right side for proper Crank position.
It is recommended to do all work from the left side and leave the factory installed right fixed cup in place; unless it is loose. Then it must be tightened first and the adjustments will be done from the left side cup.
the non-drive locking is NOT reverse threaded. lockring on track hubs are reverse threaded, but not BB lockrings.
the drive side or fixed cup is reverse threaded on most bikes, although there are many italian and french exceptions. sometimes removing the fixed cup is a piece of cake, sometimes it is extremely difficult. the most important thing is to make sure you are trying to turn it the right way. putting the flats of the fixed cup in a vise and turning the frame will remove the most stubborn of cups, if the vise blocks are square enough to hold the cup that is....