Alternative to FD?

[Ludwig II]

I've been thinking about this, and I like FD for it's simplicity, but it has wet grip and tyre wear drawbacks.

Has anyone tried an everted (turned inside out) drive belt fitted tightly, or stuck, to a pulley on the back wheel, with the drive to it coming from a toothed roller?

 

[wheelbender6]

if I understand you, that has not been tried.
Conventional belt drive systems (sheave) can also slip in wet weather.
I guess that is why you are interested in a toothed belt.

 

[Ludwig II]

I found something of interest at least to me. One can buy belts with teeth inside and out; this means a belt can be held on a pulley and drive it, while the outside is driven by another toothed wheel, and replaced when worn too much. The entire arrangement can be very minimalist, which I like. I will think a bit more about this.

 

[Ludwig II]

I think I'm reinventing this sort of thing, where a gear drove the inside of a bmx type wheel.

 

[mat_man]

Bicimoto LEM

You can see the teeth better here:

 

[Ludwig II]

Yup, dat de bunny. My thoughts are to use a large diameter driven pulley, of x number of teeth, and fit a belt to it with the same number of teeth and circumference. Drive the toothed outside of this nice quiet rubber belt with a smaller wheel, and off you go.

 

[mat_man]

Sounds closer to this earlier model:

Lem Motor Bicimoto 35cc (1970)

 

[Ludwig II]

Listen to the gear noise on this, it's nearly as loud as the engine:
https://www.youtube.com/watch?v=Qlfp0ExR3K4

 

[mat_man]

The duel levers (last 10 sec.)
And start Start at 1:20, makes me think this MB has a clutch.

Lem motor bicimoto R20 35cc (1970) XD @@@
https://www.youtube.com/watch?v=-cMrBISz494

Your video guy is using too much engine braking and has worn out his driver
gear.

 

[Ludwig II]

There are 2 levers on the bars, so it probably has a manual clutch. An exposed gear will be a noisy thing anyway. Some very old farm equipment uses them, and they have to run dry as grease or oil would attract loads of grit, but there's a very audible signal from them.

The LEM is an internal ring as well, which will trap abrasive particles rather than shed them. Interesting - what about a pair of external gears which are held close together?

 

[mat_man]

Yes "manual clutch", my bad.

Tooling cost for "external gears" is very high. High production needed.

Modifying the 5:1 gearbox to 30:1, and mounting the large gear on a disk brake hub.

3D printing the large gear and housing for custom sizes.

Like this but without the chain:

49cc 4-stroke rear side wheel motor bike kit gas engine RS4-49
http://store02.prostores.com/servlet/boygofast/the-542/49cc-4-dsh-stroke-rear-side/Detail

 

[Ludwig II]

It sticks out a long way, doesn't it?