Pinion development chart mystery?

No, that cannot be!

Simple example:

A gear down ratio of 0,25 means, if the crank does one turn, the backwheel will do a quarter turn.

The circumference of a 26 inch wheel is ~ 2 meters.

A quarter of 2 meters is 0,5 meters, not 1,30 m!

Below the calculation for the 18th gear (gear up 1,59):

26 x 0,0254 x number Pi x 1,59 = 3,29 m and not 8,28 meters!

Somebody might shout now: “You did not consider the secondary gear ratio of the (front 24 t and back 21 t) chain drive!”

(Note: The pinion drive is the primary drive).

Why should I?

In the (German) part of pdf and website it is written clearly:

“Gesamt” = entire, gross, overall, complete, as a whole

“Übersetzung” = conversion, gear ratio, transmission ratio

But ok, here it is:

1st gear:

26 x 0,0254 x number Pi x 0,25 x 1,14285 = 0,59 m

18th gear:

26 x 0,0254 x number Pi x 1,59 x 1,14285 = 3,77 m

Calculated for front 24 t and back 21 the inverse value of 0,875 (rounded 1,14285) must be used, because that’s gear up.

Did they mean front 21 t and back 24 t?

Let’s try:

1st gear:

26 x 0,0254 x number Pi x 0,25 x 0,875 = 0,45 m

18th gear:

26 x 0,0254 x number Pi x 1,59 x 0,875 = 2,88 m

Hmmm, what next?

Supposed we had a wheel size of 65 (sixtyfive) inch:

(Secondary gear ratio 1:1)

1st gear:

65 x 0,0254 x number Pi x 0,25 = 1,30 m

18th gear:

65 x 0,0254 x number Pi x 1,59 = 8,25 m

Please calculate yourself, i. e. here:

http://www.schlumpf.ch/hp/berechnungen/engl_berechnen_nabenschaltung.htm

and help me, I need your voice.

I know that I am leaning far out of the window…

(Hint: The Rohloff hub has similar gear ratios.

1st gear 0,28

14th gear 1,47)

Naturally, I wrote to the Pinion Support Team (twice).

Six days ago, there was sadly no reply.