18 speed gearbox: Good for Strida?

Found this upcoming 18 speed gearbox for bike:


For most convention bikes, the frame and bottom bracket need to be redesigned to take advantage of Pinion gearbox, thus making this an inconvenient and expensive option. On the other hand, since Strida’s BB is separated from the bike frame (or more accurately, hanging off the bottom tube), it should not be as difficult for Ming Cycle or bike modders to attach Pinion to Strida. The result would be similar to the 7 speed mod that we discussed here a few weeks ago, but simpler and more efficient.

Amuro Lee, care to ask Mark Sanders’ opinion on this?

Yes, here is Mark’s opinion:

Thanks. Good to know what he thinks about this. I wonder if by reducing the number of gears (say, to “only” 6) would contribute to lower weight and smaller size.

The Pinion gearbox in action: :wink:

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:

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.

Nicolai Helius AM w/ Pinion