Originally Posted by poopncow
Sivat -
the threading on an english bb is LH on the drive side. therefore lefty tighty & righty loosey
(the convention is righty tighty lefty loosey on right hand threads)
the crank on the drive side is spinning in a right handed manner,
the friction between the spindle and the loose cups will drive the cup in a right handed direction. WHich means that the drive side cup on an english threaded BB should be constantly being driven LOOSE. But this is not the case,
However, drive side cups come loose on Italian threaded and other BB's that have right hand threads on the drive side.
The force which spins lipless english drive side cups in and loosen italian drive side cups is NOT the spinning of the spindle, but the churning of the spindle.
We spin the spindle thru a CRANK, the crank puts a side load on the spindle and the side load changes in direction like the arms on a clock. In ways that are even harder to explain properly, it is this churning motion that causes the need for LH threads on drive side cups and left side pedals
I'm an engineer, so I know how it works. I can even derive the equations for it. I still believe that, if installed correctly, grease is the only thing needed. There is nothing wrong with using loctite for a bit of extra protection, except that you're more likely to strip the splines of the cups since there is usually only 2-3mm of engagement and the wrench handle is at least 25mm away from the plane of engagement. By the way, pedals are threaded so that they are actually loosened by the spinning of the cranks. The idea being that, in the early days of fixed gears, if the pedal bearings froze, the pedals would unscrew instead of breaking the foot.
EDIT: It occured to me that we may be arguing over apples and oranges. I was considering a sealed cartridge bb (which is what the new miche bbs shown on businesscycles are), where the cups serve a different purpose than loose bearing brackets, which I believe you might be talking about since the cups on those cannot be tightened enough to really keep them in place since they are part of the bearing race.