Martin-
When I was in Tokyo recently at a swap meet, I saw the exact same thing- it was a 151 mm BCD Campy track chainring with the large shoulder on the inside. BUT, it was 3/32"!! This was impossible. I had never seen this before- I don't believe that any 151 BCD track rings, (with shoulder) were made with 3/32" width. I showed it to some knowledgeable Japanese collectors, and at first there was excitement, because what they saw was what I saw... an impossibility! Then one noticed that both the shoulder and the teeth had been very nicely ground down. This was confirmed when I looked at the tooth profile from the edge- it was not symmetrical. It had been ground down on one side only. So, what we had was a 52T 151 3/32" road ring, (less common) made from a 52T 151 1/8 track ring, (more common). I bought it.
John Barron Minneapolis
Martin Coopland wrote:
I have an unusual chainring FS. Its a pre '67 campagnolo one, 52 teeth for 3/32nd chains.
The unusual bit is the large shoulder on the inside of the teeth circle. This makes it look like a track chainring although they are narrow 3/32nd chain teeth.
Can any one shed any light on what this was for?
Condition is used but Ok ish, surface is dull but not hugely scratched. Teeth have plenty of life left. $55 including airmail.
Regards Martin Coopland, Scotland, http://www.BatesBicycles.com
John Barron
Minneapolis
http://www.velostuf.com