chopping up and narrowing a motor

[giguana]

I made this thread because I was trying to fit a very wide motor onto an ordinary bike, but I have just tried fitting it without the freewheel and its narrow enough! so maybe I will just attach a 3 cog freewheel or a BMX one but I don't know if there are different freewheel thread standards or something.

I wonder why they make 17 cm wide wheels anyway? will a flip-flop BMX freewheel fit onto an ordinary bike?

 

[flecc]

BMX freewheels have much smaller diameter threads. I don't know the exact size offhand, but it's some 5 mm smaller in diameter.
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[mk1]

I think there are two different sizes of BMX freewheel, one type has the same thread as a screw on Cassette. The other smaller type with 13/14/15 teeth has a smaller diameter thread.

Martin

 

[giguana]

Thanks for that! This is about the space that I have for a freewheel, maximum 2 cm, what are the smallest cogs that I could put there?

 

[flecc]

That looks like a standard freewheel thread. The normally available multi sprocket ones start at five sprockets, like the 14 to 24 tooth Shimano Cadet one, and that would be at least one and probably two sprockets too wide after allowing for chain to frame clearance.

That 14 tooth is normally the smallest over the thread area, but Shimano make two front overhang freewheels, the 13 to 34 tooth six speed and 11 to 34 tooth seven speed. I've never worked with BMX stuff, so there may be a standard thread triple sprocket available, possibly with smaller overhang type front sprockets like the ones mentioned.

Maybe someone with BMX experience can advise, as I haven't seen these online.
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[mk1]

Sorry my post may have been misleading, I was talking about singlespeed sprockets available in 3 different sizes.

There doesn't appear to be room for much more than a singlespeed sprocket.

The only multi freewheels I am aware of are the 5 speed ones.
This site might help Sheldon Brown's Home Page

Martin

 

[giguana]

I found this from a US ebike seller, no idea if it will be possible to get hold of one in Europe http://www.scootonthis.com/images/jpg/parts/sprocket3gear_800.jpg
main thing is that it is possible with 1be

 

[mk1]

That looks like it could work, thats the first 3 speed freewheel i have seen.

Martin

 

[flecc]

Me too, I've never seen one before.

The question now is the thread. It could be the smaller BMX thread since a 14 tooth won't go around the full size thread. The smallest with the latter is usually 18 tooth, though it could have a very short standard thread at the rear and an internal step, not clear from the photo.
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[Miles]

I found this from a US ebike seller, no idea if it will be possible to get hold of one in Europe http://www.scootonthis.com/images/jpg/parts/sprocket3gear_800.jpg
main thing is that it is possible with 1be

It doesn't look worth getting hold of, to be honest.....

WebCyclery - Trials bikes, Singlespeeds, Cyclocross, and more.. - White Industries Dos Eno Freewheel if you can justify the expense. They're 18.5mm wide.

Miles

 

[flecc]

Useful link Miles, standard thread too.

Should run with a compact Shimano Capreo rear mechanism ok.
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[giguana]

I have found a guy on eBay that has 13t freewheels on 34 mm threads...any thoughts?

Freewheel sprocket - 16 tooth on eBay, also Other Bike Parts, Bike Parts, Cycling, Sporting Goods (end time 15-Feb-08 10:53:35 GMT)

I have opened the motor, and now I have to write down all the cable colours from the sensor wires and compare with the inside of the crystalite motor and a wire connection plugs accordingly...to run from crystalyte controllers

I know the hall sensor always has neutral in the middle, how do I tell about the order of the other two, are they always the same relative to the writing on the front?

so I will have a fast motor and a high torque one...

 

[mk1]

I didn't think it was possible to get a 13t freewheel with the 34 mm threads. As far as I know the minimum is 15t.
I will pass on the electric stuff

 

[Ian]

I know the hall sensor always has neutral in the middle, how do I tell about the order of the other two, are they always the same relative to the writing on the front?

In a word Yes.