Rotator Persuit gearing question...

rocketman58 said:

I would like to run a close ratio 12x23 9 speed cassette
on a LWB/low seat recumbent. The problem is, I still need
a wide spread of gears for the varied terrain I ride.

Quoted message said:

The Persuit with it's unique drive system, looks to be a
good choice. Can I set one up with a high around 110 and a
low under 20, and still keep a 12x23 cassete on the rear?

The gearing (in inches) on the Pursuit is given by the
following formula:

(chainring size) / (int. drive driven sprocket) * (int.
drive driving sprocket) / (rear driven sprocket) * (diameter
of rear wheel in inches)

Assumption:

intermediate drive range: 12t - 34t rear wheel diameter:
19.5 inches intermediate driving cog: 24t desired rear
cassette range: 12t - 23t

That leaves the chainring size as the variable. To get your
desired gearing range you will need to use a 33 or 34 tooth
chainring. You won't get quite the range you want unless you
use an 11t sprocket on the intermediate drive. If the
assumptions are different on your bike, you'll have to work
out the math again.

--
Bill Bushnell