Originally Posted by ThermionicScott

I had to stare at it a bit myself. Along the left side, you have the cable pull for various Shimano/Campy shifters. And along the top, you have shift ratios for various Shimano (including DA), Campy, and SRAM rear derailleurs. When you multiply the two numbers by each other, you get the RD's lateral movement per shift, which needs to match the cog spacing (pitch). For the drivetrains on my bikes, Shimano 7-speed shifter (2.9mm cable pull) times the derailleur's shift ratio (1.7) equals the cog spacing (5.0mm). Well, close enough (4.93). A lot of this data is user-gathered.

So for Shimano 6-speed, the bogey value for pitch is 5.5mm. If your rear derailleur's shift ratio is 1.9, then you need a shifter that pulls about 2.9mm of cable per shift. Hence why a couple of us figure that a regular 7-speed shifter might do the job.

Originally Posted by KCT1986

The info in the PDF is just a brief part of the explanation. Use the URL on the top of the screen capture to read all of the info. The web site isn't mine, just something I found while doing research on mixing drivetrain parts.

Regarding the comment of problems with the Microshift & RD-7402, I wonder if they were trying to use a 7 sp shifter & RD-7402 with a 7 sp spaced cogset.