Measuring Headset Stack Height

[p38lightning]

I have an 83 Bianchi with a 1 inch threaded (Ofmega) headset. I may need to replace it. I see replacement headsets commonly have stack heights of 33, or 34 milimeters. Campy has one that's 38. How can I find out what mine is? Do I first need to remove it? Is this in fact the height of all the parts stacked up as the term would seem to suggest.

 

[alfeng]

I have an 83 Bianchi with a 1 inch threaded (Ofmega) headset. I may need to replace it. I see replacement headsets commonly have stack heights of 33, or 34 milimeters. Campy has one that's 38. How can I find out what mine is? Do I first need to remove it? Is this in fact the height of all the parts stacked up as the term would seem to suggest.

The stack height is the combined height of the headset components that are OUTSIDE of the frame ... the fork race, the lower cup (with bearings inserted), the upper cup & race (again, with bearings inserted) + lock nut and/or (optional "locking") washer OR brake cable hanger (if you're using cantilever or center-pull brakes) ...

So, you do NOT need to remove the headset to measure the stack height.

The odds are that your Ofmega headset is a Campy-derivative/copy.

BTW. if the picture of the UPPER portion of the Campy headset you are contemplating looks about the same, then it will probably work ...

AND, the lock nut probably only needs about 5-to-6mm of exposed thread on the steerer, so having a taller lock nut shouldn't be a problem ... BUT, no guarantees!