Originally Posted by
HillRider
I've heard two explanations. The first is precession, which does occur and is also why English and Swiss bottom brackets have left hand threads on the drive side cup. The second sounds a bit more like an urban legand and is if the pedal bearings seize, the pedal will unscrew instead of breaking your ankle.
But the reverse threads on a pedal is on the other side as with a bottom bracket. Precession defined as a reversing of direction on a rotational axis, explains the the reverse thread on the drive side of a bottom bracket, but how could is be the same with pedals where the reverse thread is on the other side? There must be something the mitigates the procession with the pedal bearings..