[CR]Re: Campagnolo SR 39T chainring?

(Example: History)

From: <BobHoveyGa@aol.com>
Date: Sun, 24 Oct 2004 16:03:09 EDT
To: classicrendezvous@bikelist.org
Subject: [CR]Re: Campagnolo SR 39T chainring?

RDF1249@aol.com writes:
><< Check this out: http://ebay.com/<blah>
>I did not think this was possible. 41T was as small as I have heard of or seen. Even with that size you must relieve the crankarm for chain clearance.So I wrote to the seller, and he said: This 39T chainring was produced by Campagnolo solely for professional teams, as a 'granny gear' for the big Alpine mountain stages. It was never introduced to the retail market. Its 84.6mm across.

Since photos don't lie, I downloaded the pic and brought it into Photoshop. Using the measure tool, I got the distance between teeth (which should be 1/2" in real life), both at the top and bottom of the ring, and then averaged the two (to compensate for perspective distortion). I then did the same thing for the distance between bolt holes and calculated the actual distance using the tooth pitch as a reference. The result was 76.77mm, not the 86.4 the seller claims. This translates to a BCD of 130mm. I remeasured every which way to see if I could massage the figures to come out to 135 BCD, but no way... so I'm doubtful this is even a Campy ring.

Bob Hovey
Columbus, GA