New Pedals Size For A Truvativ Isoflow Road Crankset

[Tennjed]

I am a newbie and i want to replace the pedals on a Truvativ Isoflow Road crankset. How do i know if I need 9/16 or 1/2

 

[dabac]

9/16" is pretty much everything these days. 1/2" I've only seen on one-piece (ashtabula/Fauber cranks).

Then there's a rare French standard lurking somewhere too.