Originally Posted by
rootboy
That's very interesting, Rep. Other than a few cosmetic changes they made through the years, ie; the shape of the back plate, the location of the return spring pivot, etc., I didn't realize they had made changes in dimensions of the basic design. I think the newest example I have here is a Pat. 81, and the oldest a Pat. 72. I'll have to look more closely at them. I seem to be able to use a 14-28 on the Pat. 74 on my Le Champion, with a bit of finessing.
I have to find my notes again from when the change occurred.
It is one of those subtle changes that just don't show unless you have two in hand and a caliper.
What got me thinking of it was the very early units had a more organic flow of surface from the material adjacent to the upper pivot and around to the link pivot pins.
"why was that?"
The parallelogram links did not change early on, but the distance from the upper pivot to the links did, and I recall the same for the lower, so the jockey cage pivot was moved further away from the rear wheel axle.