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I have noticed the chainstay stops are unusually placed as well:
The extra stop could be for the front tension arm of an Osgear.
Here's a 1949 Paris with an Osgear with tensioner cable:
http://www.classiclightweights.co.uk/bikes/paris-eric-rb.htmlMy frame has Agrati drop outs instead of Osgear drop outs. I think they are original going by the paint, but I am wondering if they have been replaced as there is no serial number on the frame, only on the steerer tube.
benjaminbunny
Rik_Van_Looy
Stallard Zakopane brazing:
Another guess: This cable guide could be intended for use with a double right hand lever. There was once a theory that pressure on the chain caused by a powerful chain tensioning spring caused an unacceptable amount of 'friction' in the transmission. The answer was to provide manual chain tension with the extra lever so that when descending at speed on the small sprockets more tension could be applied to stop then chain coming off - when climbing on the bigger spockets the pressure would be realeased by slackening the tension cable. This arrangement was in addition to the conventional spring. I believe both Huret and Simplex tried this but, as you will have guessed, it wasn't very successful.
I think the second RH lever was sometimes used for a cable controlled front changer, but I have a feeling this was only because the original purpose was a failure - surely it's easier to control the front changer from a LH lever.