100 feet * 12 inches per foot / 1640 drive links per roll =0.732 inches between drive links. rounded off .7317......
For 7 tooth rim
0.732 * 7 = 5.124 inches circumference at rivet centers
5.124 divided by pi 3.14159(....... ) =1.631 inch diameter at rivet center circle
For rim drive I see 1.380" for 3/8 7 tooth subtract from 1.631 and divide by two = 0.1255 or real close to 1/8 inch which is realistic for the sliding surface of 3/8 chain to rivet center I would think.
I measured .15 to .16 from the (od of a 3/8-7 1.383) to the center of the rivet.
Not sure if the shape of the tie strap might complicate things to a minute amount.
For the 8 tooth spur, I did the math for 7 by accident first so will do for 8
5.856" circumference at rivet center, yes
1.864" diameter at rivet centers which should be measurable. Yes, that measures good, they rock a bit.
(1.864-1.667)/2=0.093" for offset notch at tie strap center to rivet center. That looks correct as best I can see with a caliper.