Headtube size question (possibly stupid)

[halmot]

I'm working on an old 70s-vintage steel road frame, and I'm concerned about finding a suitable headset. Measured with a caliper, the head tube ID comes out to about 30.75mm. I thought that maybe it was simply worn, but what's left of the old crowns fit snug, and measure in at 30.8mm.

I've looked around on the 'net and I haven't found any reference to such an odd-sized tube. Can anyone tell me what I'm dealing with here? Are shims available to let me fit a "standard" headset, sized for a 30.2mm head tube?

 

[halmot]

Maybe I'm just measuring wrong?

 

[boudreaux]

Originally posted by halmot
I'm working on an old 70s-vintage steel road frame, and I'm concerned about finding a suitable headset. Measured with a caliper, the head tube ID comes out to about 30.75mm. I thought that maybe it was simply worn, but what's left of the old crowns fit snug, and measure in at 30.8mm.

I've looked around on the 'net and I haven't found any reference to such an odd-sized tube. Can anyone tell me what I'm dealing with here? Are shims available to let me fit a "standard" headset, sized for a 30.2mm head tube?

Never heard of such a thing, or shims of that size either. Ask Sheldon Brown at www.harriscyclery.com

 

[halmot]

Originally posted by boudreaux
Never heard of such a thing, or shims of that size either. Ask Sheldon Brown at www.harriscyclery.com

Update:

As usual, Sheldon did have an answer (I do try to spread my dumb questions around, so as not to be too much of a pest to dear Mr. Brown).

It appears to be an old Austrian standard. A bit more research revealed that some of the Sears department-store frames of this vintage were manufactured by Steyr/Puch.