As for the motor, and physically connecting it; what's your plan? In other powered bike kits I have seen from the 80's, the motor shaft has a small wheel to rest on the back tire; pretty straight forward. keep in mind the gearing of the specific bike you have when setting it up; most have the freewheel mechanism as part of the rear wheel, so if you connected the motor to the drive chain somehow, you run the risk of turning the pedals into a heel & calf puree machine.

I was planning to make it chain-driven. I was thinking of finding a small sprocket from an old bike to attach to the motor, and then have a chain that connects it to the rear sprockets. I believe there's already a special catch mechanism that would prevent the pedals from turning when they're not supposed to. I think this would probably be the easiest way to do it, but I'm still definitely open to suggestions

 

I was planning to make it chain-driven. I was thinking of finding a small sprocket from an old bike to attach to the motor, and then have a chain that connects it to the rear sprockets. I believe there's already a special catch mechanism that would prevent the pedals from turning when they're not supposed to. I think this would probably be the easiest way to do it, but I'm still definitely open to suggestions

I don't have your bike in front of me, but every bike I have ever worked on (a lot. when I was younger, used to buy, fix, sell, create custom bicylces)had the freewheel mechanism (or special catch mechanism as you say; I don't know the correct name for it; clutch?) inside the rear wheel, attached to the shaft. the shaft will engage the inside of the wheel when pedaled forward, and disengage when pedaled in reverse (or when the rear tire overspins the sprocket). It sounds like you are talking about a multispeed bike with more than 1 sprocket in the back. The normal configuration would be that all of those sprockets are connected together and connected by chain to the pedal sprocket(s). If you connected the motor to one of the back sprockets I think you will create the leg blender I mentioned; check your bike and make sure I'm wrong about that.

easy way to find out is turn the bike upside down and spin the rear sprocket set in the forward direction; if the pedals don't turn, safe; if they do, unsafe.

if you could find a way to attach a seperate sprocket to other side of the rear wheel, I think it would be safer.

 

The word you are looking for is "ratchet". I used to take apart my bicycle hub, sprocket and bearings, clean and grease the parts all the time when I was a kid. Not too many kids know how to do that these days.

 

I don't have your bike in front of me, but every bike I have ever worked on (a lot. when I was younger, used to buy, fix, sell, create custom bicylces)had the freewheel mechanism (or special catch mechanism as you say; I don't know the correct name for it; clutch?) inside the rear wheel, attached to the shaft. the shaft will engage the inside of the wheel when pedaled forward, and disengage when pedaled in reverse (or when the rear tire overspins the sprocket). It sounds like you are talking about a multispeed bike with more than 1 sprocket in the back. The normal configuration would be that all of those sprockets are connected together and connected by chain to the pedal sprocket(s). If you connected the motor to one of the back sprockets I think you will create the leg blender I mentioned; check your bike and make sure I'm wrong about that.

easy way to find out is turn the bike upside down and spin the rear sprocket set in the forward direction; if the pedals don't turn, safe; if they do, unsafe.

if you could find a way to attach a seperate sprocket to other side of the rear wheel, I think it would be safer.

Yes, I have an 18-speed bike, so 3 sprockets on the pedals and 6 (stacked) on the rear wheel. I have already turned the bicycle upside-down and done as you suggested. I spun the wheel in the forward direction and I am fairly sure the pedals did not turn. That is why I figured it would be a safe way to do it. On the other hand, an extra sprocket on the back specifically for the drive motor is a good idea. I will definitely look into that.

 

The word you are looking for is "ratchet". I used to take apart my bicycle hub, sprocket and bearings, clean and grease the parts all the time when I was a kid. Not too many kids know how to do that these days.

Not many kids knew how to do that when I was a kid either (only about 15 years ago); actually, none of them did, which is why I was the neighborhood bicycle mechanic. My kid will know how to do it too.

 

I spun the wheel in the forward direction and I am fairly sure the pedals did not turn.

I said spin the Sprocket; after all, the sprocket is what the motor is proposed to turn, correct? And yes, there is a difference between spinning the wheel and spinning the sprocket.

 

The name for the part in the hub is a 'freewheel'. Here is a link to a cool bicycle site that may help on your journey; http://www.atomiczombie.com/ct-freewheel.html

 

Perhaps you could use an in-direct drive type system through a Sturmey Archer hub? Although this would mean having the rear wheel re-built around a new hub which was able to handle the torque (assuming you're talking about rear wheel drive system?)

As for connecting the motor to the rear sprocket, you could do it directly however as mentioned previously the jolt problem occurs meaning that the bike will likely just disappear between your legs once you hit the GO button, or all the spokes will snap in the wheel leaving you sat rather lower to the ground

I think getting the bike moving first would be a must or you're going to need to implement a clutch type system, perhaps a lever could be used on the handlebars in conjunction with some sort of smaller clutch mechanism, a bit like a motorbike?

http://www.sturmey-archer.com/products/hubs

 

You could mount the motor to contact the tire or rim like the original gas-powered mopeds... or you could get an e-bike motor kit:

http://www.ebikes.ca

 

I said spin the Sprocket; after all, the sprocket is what the motor is proposed to turn, correct? And yes, there is a difference between spinning the wheel and spinning the sprocket.

I'm sorry, I guess I mis-read that. I will go try that now and will get back to you soon.

As for connecting the motor to the rear sprocket, you could do it directly however as mentioned previously the jolt problem occurs meaning that the bike will likely just disappear between your legs once you hit the GO button, or all the spokes will snap in the wheel leaving you sat rather lower to the ground

I think getting the bike moving first would be a must or you're going to need to implement a clutch type system.

I was not planning on having just a "GO" (on/off button) for the motor. I will be using PWM, so perhaps a sort of spring-loaded lever thing (just a broad idea at this point) to adjust the motor speed. That way I would have an on/off switch, but the motor wouldn't move until I applied pressure to the throttle ("lever"). That, I believe, would eliminate the "jolt problem".

 

I was not planning on having just a "GO" (on/off button) for the motor. I will be using PWM, so perhaps a sort of spring-loaded lever thing (just a broad idea at this point) to adjust the motor speed. That way I would have an on/off switch, but the motor wouldn't move until I applied pressure to the throttle ("lever"). That, I believe, would eliminate the "jolt problem".

Ah yes PWM control would be great. Don't forget to post pics if this comes off.

Don't forget my ideas though just in case you eventually decide to build a drag bike instead

 

Ah yes PWM control would be great. Don't forget to post pics if this comes off.

Don't forget my ideas though just in case you eventually decide to build a drag bike instead

I'm thinking of doing a blog on it, pictures and all!

Even if I don't use some ideas for this project, they are sure to come in handy in the future. Thanks everyone for all the suggestions

 

I said spin the Sprocket; after all, the sprocket is what the motor is proposed to turn, correct? And yes, there is a difference between spinning the wheel and spinning the sprocket.

Hey, I gave this a try, and of course, the pedals turned. I did notice a sort of flange (probably not the right word, but oh well ) attached directly to the wheel, It may be possible to attach a sprocket on it for the motor chain. I'll have to look more into that.

 

Just in case anyone decides to try using an automotive starter motor to propel something, BE VERY CAREFUL!

They have electric drag-racing cars that use 24-volt truck starter motors with on/off control only and the drivers use a special strap to make sure their necks aren't snapped by the starting jerk. They easily beat the liquid-fuel-powered dragsters, too. So those motors can REALLY get a vehicle going FAST, and quickly!

Also, I know a guy who built an "electric motorcycle", about 30 years ago, as a university project. He used two 24V truck starter motors and quite a few automotive batteries. It had only on/off control. Even with the weight of the batteries, he said it was absolutely terrifying and death-defying, the one time that he rode it, which was on a long, straight test track.

 

Just in case anyone decides to try using an automotive starter motor to propel something, BE VERY CAREFUL! Those motors can REALLY get a vehicle going FAST, and quickly!

Hence my plan for PWM

 

All this talk and no substance ...without load a starter motor draws about 40 A and goes 11000 rpm. Stalled it will pull 400A Running as in cranking a vehicle about 180A.and 1000 rpm ..Forget lipo and all that just stick with a lead acid . A vehilce dynamo will run as a motor ...22A at 12v 265 W better bearings ..belt drive ..chain drive more efficeint and increasing the speed from about 800 rpm is easy by reducing the field current

 

All this talk and no substance ...without load a starter motor draws about 40 A and goes 11000 rpm. Stalled it will pull 400A Running as in cranking a vehicle about 180A.and 1000 rpm ..Forget lipo and all that just stick with a lead acid . A vehilce dynamo will run as a motor ...22A at 12v 265 W better bearings ..belt drive ..chain drive more efficeint and increasing the speed from about 800 rpm is easy by reducing the field current

When you say dynamo, are you referring to the old "generator" types or the newer Alternators? I would think some modification would be needed to use an alternator as a motor (such as adding magnets to it)

 

Check these motors from All Electronics:
CAT# DCM-130, DCM-2413, DCM-1250 & 12V DCM-517
Yes, we used 6V & later 12V Ford starter motors to drive cable reels, loaded about 300 lbs. [ 1950-1963 ]. I modified front bearings to ball. Figured HP at about 2. Semi continuous duty.

 

All this talk and no substance ...without load a starter motor draws about 40 A and goes 11000 rpm. Stalled it will pull 400A Running as in cranking a vehicle about 180A.and 1000 rpm ..Forget lipo and all that just stick with a lead acid . A vehilce dynamo will run as a motor ...22A at 12v 265 W better bearings ..belt drive ..chain drive more efficeint and increasing the speed from about 800 rpm is easy by reducing the field current

I've been doing some more reading up on turning alternators into motors and seems there's 2 ways of doing it; 1 is to add magnets as I mentioned; the other is to put DC into the field as you mentioned. http://www.evalbum.com/876

This cart uses alternators, but you need a 3phase input @ 60V. generating 3 phases shouldn't be too much more work since you were already going the PWM route, but I think you are going to need more than 12V.

here is a topic: http://www.endless-sphere.com/forums/viewtopic.php?f=3&t=6584

if you were able to generate 3 phase @ 60V, I think an alternator would be *safer and *better (easier to control).

 

No you can run an alternator as a motor ..engergise the rotor with about 6v dc and feed the three phase stator using an 80A model aero motor controller ( which produces 3 phase from the DC ) Been done many times and you can buy if you want a rotor with magnets .... A large radiator fan motor would be a better propositon than the starter motor or alternator .