Originally Posted by jimshapiro
How does a sem-logarithmic graph "normalize the viewing"? The purpose of such plots is to linearize exponential relationships, generally for curve-fitting purposes, but everything here is linear. The overlap and shift points, whereever they are, will be on both linear and semi-logarithmic plots, just in different places. Does it have something to do with the angle of the chain between extreme positions of the chainrings and cogs?
What I should have said was "normalise for webpage viewing". My guess is that the author wanted this ascii plot to fit within the boundaries of the webpage. I agree that it's all linear. And in hindsite, he probably should have just plotted it on a linear plot. It also looks like his plotting code may be slightly flawed because it generates some incorrect positioning. Here's the linear plot. Notice some of the cog positioning relationships have changed around the 60 to 65 gear-inch range.
Code:
Linear Graph
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I 1 2 3 4 5 6 7 8 9
M 1 2 3 4 5 6 7 8 9
O 1 2 3 4 5 6 7 8 9