Originally Posted by
Iride01
I disagree. Think about which way the pedal turns with respect to it's hole in the arm. Not the way the pedals turn the crank.
You can disagree if you like, but you'll be wrong.
Read Jobst Brandt's very thorough explanation of bearing precession, posted at sheldonbrown.com.
Left side pedal spindles have left hand threads (and right have RH) because bearing precession would loosen them otherwise, in spite of how the forces appear to work. With plain bearings (sometimes called bushings), they would loosen or tighten as you'd expect when looking at them. With ball or roller bearings, it's reversed.