Bike project 1: More gears

Spent some time sorting through gear issues.  The wheel diameter issues can be dealt with by a 1.3 gear that makes the 20" wheel equivalent to a 26" wheel.  The issue then becomes the gear range.  Here are some of the spreadsheet results.  The key seems to be the mid and rear gear ranges and the drive gear on the mid.

Switching to 9 speed cassets gives these results:

The key here is the 11 tooth which gives good high speed and the 34 tooth that gives good low speed.  The mid gears also provide a very low low and very high high gear.  As a practical matter reducing the mid drive gear to a 22 or 24 gives better range with a low speed below 2mph and a more reasonable high of around 30mph.