Bicycle Mechanics - Headset stack height

My Nuovo Record headset has developed an "index". It went away when I backed off the adjustment just a hair and still has no play, but I'm thinking I may want to replace it over the winter. Since NR headsets can no longer be found for a reasonable price, I'm thinking of a Stronglight A9 roller headset, which should be a lot more bulletproof. These have a stack height of 37mm. Would it be a direct replacement for the NR. How, exactly, do you measure headset stack height?

See below.

Harris Cyclery says the A-9 is 40.2 while Velo Orange says it's 37.0. I guess I just added to your confusion. You won't be confused about where to buy it if you check their prices.

It's a very nice headset. I have two. If you don't like the logo, you can esily remove it with metal polish. You'll find the same advice on the Velo Orange site. It came from me.

If you are NOT mail ordering it, take your old HS to the shop and compare it in real life.

How, exactly, do you measure headset stack height?

Measure your fork's steerer tube with the crown race removed. Subtract the length of your frame's head tube with the headset cups removed. The difference is head set stack height including spacers.

http://i4.photobucket.com/albums/y115/reciprocity/stackheight.jpg

Thanks, operator! Exactly what I needed. :)

As an added note, if the new headset has a shorter stack height than your current one, you can add spacers to get the top nut to thread on properly.

Anyone know the stack height of the 80's Campagnolo Super Record headset? I may be replacing one and don't have the bike (nor all the parts, hence the reason I may need to replace it) to do the measurements. Replacement options are either the Stronglight A9 or a modern Campy Record.