Sprockets question

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reikiman
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Sprockets question

Hi, wonder if someone can give me some advice about something which has been perplexing me for awhile.

One of my projects is a chopped up modified bicycle, I've removed the bottom bracket area & crankset etc, and am planning to use only an electric motor to drive the rear wheel.

The issue is about having the same kind of sprocket on the motor as is on the bicycle rear wheel.

Related issue is having a large enough sprocket on the rear wheel for the desirable gear ratio. And no I don't know what the gear ratio should be, as I've not connected the motor to the controller to see what it's RPM is.

The motor has a 1/2" shaft and can take a setscrew.

The existing rear wheel has the typical shimano cassette. That means the cassette mounts over a splined cylinder. I forget the correct technical terms.

The sprockets I find for a 1/2" shaft are for normal roller chain. In the #40 size it is the same pitch as bicycle chain but wider. That means bicycle chain doesn't fit on normal sprockets for electric motors, and normal roller chain doesn't fit on the bicycle sprocket on the rear wheel.

Any ideas?

garygid
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Re: Sprockets question

Make, buy, or have made, an adapter plate for the motor shaft.
Mount a bicycle sprocket onto the plate, and then use
bicycle chain that is made for those sprockets?

Cheers, Gary
XM-5000Li, wired for cell voltage measuring and logging.

reikiman
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Re: Sprockets question

Hm, that's an interesting idea. There are 'weld on sprocket hubs' that would be the base for the adapter plate you suggest.

I just came up with an alternative that's similar. Took the cassette off the rear wheel again and learned that the piece with the splines is weldable steel. This means I could take a sprocket with a wide enough bore to fit over the splines, and weld it into place.

garygid
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Re: Sprockets question

I was thinking of a simple cylinder with a hole down its axis for the motor shaft. Use a key or a set screw or two into the shaft key-slot. Then, just drill a few holes to bolt the sprocket to the face of the cylinder.

But, whatever construction you can do best ... I do not have welding equipment.

Cheers, Gary

Cheers, Gary
XM-5000Li, wired for cell voltage measuring and logging.

reikiman
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Re: Sprockets question

Make, buy, or have made, an adapter plate for the motor shaft. Mount a bicycle sprocket onto the plate, and then use bicycle chain that is made for those sprockets?

Just wanted to note.. I remembered just now (thanks to Whats best hub motor or the type use in the Cheetah homebuilt?) that the Cheetah Builders Guide goes over this very question.

I had thought it would be cool to use the existing deurailler for some purpose or other. But really electric motors have such a broad power range it isn't necessary to change gears.

In the Cheetah plan you remove the freewheel from the rear wheel then build up an adapter that slips over the freewheel splines and bolt a regular (e.g. #40) sprocket to the adapter. Probably it'll take some care to ensure the adapter is perpindicular to the axle, and securely fastened to the splines.

Rabbitbunny
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Re: Sprockets question

No. Visit your local machinist and have the #40 sprocket thinned. They can do it quite quickly on a lathe, probably $20.

PJIII
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Re: Sprockets question

You could try #25 chain which , to my understanding, is common e-scooter chain. This link will show you some & they have chain also.
electricscooterparts.com/sprockets.html
Here is another link for sprockets & chain etc.grainger.com/Grainger/sprockets

You may have to modify some parts adapting them to suit your need by cutting & welding.http://www.grainger.com/Grainger/sprockets/power-transmission/ecatalog/N-arcZbk2?op=search&sst=subset
http://www.electricscooterparts.com/sprockets.html

Cyclone 650 watt 24V trike

reikiman
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Re: Sprockets question

I went a different route with that specific project (see my other postings on the stretch bicycle). But I still have that modified bike frame and could build something with it and will probably do something like you say.

In Bidwell's book - Cheetah - which shows essentially the plan I followed on that bike frame - he does make a recommendation like you suggested.

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