headset threading
 

OK, looking for the people well versed in headset threading. What is the rule regarding headset threading:
Can english threaded headsets work on italian threaded steerers? What about vice versa? I know the French steerers are actually smaller diameter tubes, but the italian and english steerers should be same diameter, just different threading. Thanks for any help on this! (Next weeks discussion, bottom brackets!). Ed

nope not without a hammer or a die set

English and Italian are, as far as I know, compatible.

english and italian are actually the same dimensions and pitch (1" x 24T v. 25.4mm x 24T, 1" = 25.4mm), but with a different yet very close thread angle..
they are regarded as interchangable, but it is not recommended to switch back and forth

french headsets are different pitches, not compatible
bottom brackets are all different dimensions and threading

Yes, ISO headsets will work on Italian threads, not sure about the reverse. Scroll down about halfway on Sheldon's threading page for headset info:

http://www.sheldonbrown.com/gloss_ta-o.html#threaded

Thanks people!