what would happen...

Mobius

New Member
Jul 29, 2008
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Oregon
If I welded a sprocket to the driveshaft and connected it to the sprockets on the back tire via a small chain???

would this be an effective way to power the bike???
 

Dave31

Active Member
Mar 1, 2008
11,204
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38
Aztlán, Arizona
That's what I am doing...but I am not going to weld the sprocket to the shaft. I'm having trouble finding the right sprocket to fit the shaft with the gearing that I'm looking for.

So until I find the right sprocket I'm using a old one off a old MTB that I have to get thing's ready for when I do find the right sprocket.

I welded the sprocket to the sprocket of the one that does fit the motor...keep in mind this is just for mock-up

Hmmm....I'm having trouble uploading my pics. Check this thread later on for pics...http://motorbicycling.com/f36/my-diy-project-2444.html
 

Mobius

New Member
Jul 29, 2008
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Oregon
what kind of gearing would you suggest???

and you wouldnt weld it you would just fasten it up with bolts???

I guess this is an interesting idea... In that case couldnt you just take some kind of metal disc and bolt the correct gear to it and go from there?

You could almost change teh angle of your derailleur so that it could change what gear the motor was engaging.

You might be on to something
 

Mobius

New Member
Jul 29, 2008
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Oregon
is that a bicycle sprocket or something bigger??? how did you attach it?

I was thinking jsut to add a single to the top and maybe realign the derailleur.
 

Jemma Hawtrey

New Member
Dec 29, 2007
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Essex, UK
Do you mean a shaft with the cassette on it and a single sprocket at the back?

That would actually make more sense than the usual way because the change is nearer the motor and torque source and you'd get less trouble from the chain such as it jumping and such.

Im interested in seeing what you come up with on this

jemma xx
 

jasonh

New Member
Jun 23, 2008
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Longmont, CO
hmm, or even a cassette on both ends and two derailers! That would be an interesting one. Get a whole boatload of gears that way, lol. Ok yeah, I'm a little nuts :)
 

Dave31

Active Member
Mar 1, 2008
11,204
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38
Aztlán, Arizona
The motor will have a single sprocket...I will be using the existing cassette sprocket already on the wheel.

I'm just using this cassette sprocket to mock-up. The gearing will not work...No way will I be able to take off from a stop with this gearing. The motor has a gear reduction with a centrifugal clutch.

The small sprocket is the original that came with the motor..I welded it to the cassette sprocket.
 

Mobius

New Member
Jul 29, 2008
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Oregon
jemma said:
Do you mean a shaft with the cassette on it and a single sprocket at the back?

That would actually make more sense than the usual way because the change is nearer the motor and torque source and you'd get less trouble from the chain such as it jumping and such.

Im interested in seeing what you come up with on this

jemma xx
I was thinking of mounting a single sprocket to the driveshaft and running the chain down to the mainsprockets on the rear axle and making the derailleur work for it instead
 
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Jemma Hawtrey

New Member
Dec 29, 2007
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Essex, UK
hmm, or even a cassette on both ends and two derailers! That would be an interesting one. Get a whole boatload of gears that way, lol. Ok yeah, I'm a little nuts :)
Its doable, but not easy to set up because you would end up with duplication of ratios if you werent careful - let alone the other logistical bits and pieces with the controls and such..

Nah you arent that far into being nuts lol

Jemma xx
 

deacon

minor bike philosopher
Jan 15, 2008
8,117
3
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north carolina
I had so many problems with the chain system on the china bike that I swore if I ever built a bike it would be friction drive all the way. I would rather buy a ten dollar tire a couple of times a year than a $35 wheel once a year when it throw the chain threw the spokes and leaves me stranded. That's just me. I'm also not at all into speed, so friction drive is good for me.
 

Mobius

New Member
Jul 29, 2008
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Oregon
Im not thinking of it so much for speed but I live in the portland area where it rains frequently(trouble for friction), that combined with the fact that I weigh 285 lbs and Ive heard friction systems will hammer in a nail thorn etc. and I already deal with flats almost monthly I just assumed that chain drive would be more practical.

are you saying that the chain will break or just jump the sprocket???

Im interested in this whole thing so naturally I want to do what is going to work best for me and my location
 

deacon

minor bike philosopher
Jan 15, 2008
8,117
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north carolina
I have no idea what will happen on a 'roll your own' bike... The china bike has a tendency to throw the tensioner through the rear wheel now and then. At least it did for a while with me. I have no idea what will happen with your build. I never tried it.

Yeah I'm retired so I am NOT going to ride in the rain. Nothing in this world I need that badly. I haven't moved my car in months so as far as I'm concerned it is motor bike all the way now.

My wife still drives and if I had anything big to get I wait till she is going places near there. I do have to get some bike parts for another bike I am building the chainsaw bike. I will ride the China bike for that since I have not thoroughly tested the 31cc front mount bike yet.

I haven't had the push a thorn into a tire yet, but I mostly ride on city streets for errands. I know one thing If I build another bike I am going to go with a suspension bike next. The potholes here and the uneven repairs are awful.

Anyway keep us posted I'm curious to see how you and racing do with the build. You do know you are likely going to need clutch of some kind, unless you can drag start the engine at every stop sign. I did that with a 25cc engine and it was fine as long as the stop sign didn't leave me with an uphill start.
 
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Mobius

New Member
Jul 29, 2008
28
0
0
Oregon
deacon said:
Anyway keep us posted I'm curious to see how you and racing do with the build. You do know you are likely going to need clutch of some kind, unless you can drag start the engine at every stop sign. I did that with a 25cc engine and it was fine as long as the stop sign didn't leave me with an uphill start.
I hadnt thought of a clutch... Hmm that throws a bit of a wrench into it. I just want to be able to go and possibly shift on the fly.

I guess its food for thought
 
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Mobius

New Member
Jul 29, 2008
28
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Oregon
Im not talking about welding to the shaft I was thinking more along the lines of welding a plate that will fasten to the shaft to a sprocket that is the correct gearing. and going from there
 

Ilikeabikea

Active Member
Jan 27, 2008
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Ptown, Texas
How big of a gear would you have to put on the back tire to be able to use the engine? Or how small of a drive gear on the engine? Won't you need a jackshaft? Ok now I got to get my calculator and start figgerin.................
 

Mobius

New Member
Jul 29, 2008
28
0
0
Oregon
My thought was just to use the smallest sprocket from the pedaling assy. that way you would be using the same basic gearing.

another question, If I used a chainbreaker and made the chain just the right length wouldnt that eliminate the need for a tensioner?

I really like the idea of friction because its so much simpler but something tells me that the portland oregon climate wont really allow it.

Does anyone have an idea of how to make a friction drive that is less prone to slippage?