Alt Bike Culture - Questions on building my first chopper

I just got into building choppers and I noticed that there are different sizes of headset in the chopper world than in the mountain/road bike world.

I was given a chopper from someone because the head tube is bent so I'm buying a new frame to put all of the old parts on the new one. But I don't know how to measure the head tube to determine what size head set I need. I noticed on a chopper part websites that there are the standard 1", 1 1/8", but then there's 22.1mm, and 22.2mm. What is the difference between the inch and mm measurements and how do I find out what size my springer fork is and all that j***. Thanks!!!

for those kinds of bikes (someone correct if im wrong here) i think that the only 2 measurements you'll need to know is 1 inch and 1 1/8 inch. those measuremente refer to the outside diameter of the steer tube. you'll also need to know if your head set is threaded or threadless. most threaded headsets are 1 inch, most threadless are 1 1/8 inch, but of course there are exceptions especially when ya start gettin into roadbikes and older roadbikes. you'll also need to measure the length of the steer tube that comes out of the frame, and preferabley take it w/ you to the shop to order/buy your new one. sometimes it helps to stand on one leg and whistle while twirling. fast eddie outty

The difference in stiffness between the two is absolutely shocking.

hehe, uh hehehe....(laughing like beavis and butthead) you said "shocking stiffness"