mickle said:
RH BB cup is a LH thread and screws into the frame. An external flange tightens flat on to the face of the BB shell. Balls (with or without ball cages) and axle are inserted and the LH BB cup is screwed in and then fine tuned to adjust the bearing preload. The BB lock ring screws onto the LH cup to prevent it from moving once the bearings have been adjusted.
yep, this is pretty much how it was.
the LH BB cup uses the same thread on the outside of it to screw into the shell and to have the lockring tighten onto it - this was the bit i dint' get but having seen it it's obvious how it works. So the lockring can be tight onto the cup against the shell, while the cup itself isn't too tight in the shell against the bearings, 'adjusting the preload' as you say.
So once the LH lockring was off (with a pipe wrench) the cup just unscrewed by hand, by gripping its threads - no tool from lidl required
(nor would even have been useful...)
the RH cup ('external flange' as you call it) was slightly harder to get off (no not because i was screwing it anticlockwise), have to be quite careful with the pipe wrench but not too difficult.
the bottom bracket on my mountain bike was a different beast altogether - it doesn't look like it would surrender to a pipe wrench and i don't really want to take a pipe wrench to it - it looks like it will need one of these type of BB tool with many external notches:
so that's not going to happen till tomorrow! bugger...