re-tapping a french threaded crankset to 9/16"

[Dead Rats]

Anyone done this mod? Reading Sheldon it seems easy enough provided you have the correct tap - but my key question is... do you need different tap for left and right arms?

cheers,
Al

 

[monty dog]

Yes, because driveside is lefthand thread whereas NDS is righthand.

 

[keithglos]

Monty, I think the OP wants to tap pedal threads, 9/16", Right hand pedal is RH thread, left pedal is LH thread.
The origin was that if a pedal seized, it would unscrew, not break an ankle.
Alloy cranks fairly easy, cheap steel with pressed arms ("joggled") or chainring are doable, forged cranks with arms made in one piece very tough.

 

[Dead Rats]

yes, to confirm my OP I'd like to re-tap French pedals thread to standard 9/16"