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Discussion in 'DIY Home Built Motorized Bicycle (non kit)' started by Bikeguy Joe, Nov 25, 2008.
sounds like a plan
The first thing I have to do is to choose a motor. Actually I have a few still laying around. I have only friction drive since it is what I like the best. One of them has a small twist but it's still basically friction drive.
Now that I can weld, (not well yet but still I can butcher metal) I can make a decent mount. Right now I'm thinking front wheel drive but everything over the wheel for balance, rear luggage carrier also over the wheel for the battery pack. With a small rear wheel the balance might be pretty good, even with the heavy batteries balanced over it. I can build a good solid carrier for the batteries.
Should be interesting to see what I can salvage from the junk I have laying around. Well I guess I will give it some serious thought tomorrow.
I am looking forward to this....been thinking of an electric of my own....made of wood.
Now you are talking third world bikes by joe...
I have a couple of prelim questions. My first purchase might just be a brand new (heavern forbid) bike. I hear the gasps already.
Okay I always thought bikes with gears were for wimps, but alas that might be the way to go with this build. So I'm going to pick your brains for ideas,
Now on a 99speed bike, they have two sprockets on the crank. Do they both turn at the same time. I ask that because a brushed electric motor will charge the batteries when it is moving faster than being called for. Ie not in use at the time.
If they do I might pick up one and try to run the electic engine to the smaller of them. Then pedal with the big one and the few gears that are left to me. If that works I could conserve a lot of battery by leaving the engine off most of the time. I see these old farts er guys going down my street all the time on those bikes. So it wouldn't be a problem to coast with the engine off or even go on the flats. Plus I could take the thing on the bike trails nobody would know.
Second question. How hard would it be to remove the smaller one and put on a different crank. I have a #25 large sprocket and chain plus that is what comes on the motors I have. Now that would be the cats meow if I could switch those out.
If not i can get a flat bike sprocket and weld it to the sprocket on the engine. The bike sprocket is larger so it won't be a problem. Well it will be a balance problem but nothing more.
Unlike a gasoline engine the electric freewheels no problem. Just shut it down and it becomes a little drag but nothing else. And my motors even charges the battery,
So answer up guys and help the fatboy with his ebuild...
I'm thinking about this on the motor mounted to the from above the crankset. Chained to the smaller of the chain rings.
all the gears on the front crank will move together when you pedal
That should be fine the electric motor will free wheel and actually charge the battery when not in use. I would just have to remember to turn it off so that the pedals wouldn't beat me to death going downhill.
I really am in a quandary. I can buy a suspension mountain bike with all the bells and whistles for a hundred bucks at wallymart, or I can buy a sprocket like on the china kit for the bike I have and mount the motor to inside of the seat post and run the chain that way. The twenty inch rear wheel and small sprocket on it now makes it a good hill climber. Have to do some thinking.
Or I could look for a thrift store bike with two front chain rings and just move the small wheel to it and remove the gear stuff from the rear. I do that all the time.
either one is doable it seems.
I have been thinking about how to attach the motor to the frame of the bike. I think I have the method worked out. I will weld a six inch heavy bar to the bike frame cross way under the top bar. Then I will attach the motor with a couple of large pipe clamps from the plumbing section of the hardware store. That will allow me to adjust the position of the motor easily. Those clamps are pretty strong.
Im still trying to decide whether I want the china kit sprocket or to use the extra chain ring. The china kit would allow me to ride it under power even faster than I want to pedal, but I primarily want the bike for exercise and to run short errands so do i want to ride it under power most of the time?
Something to think about. By the way if I can I will take the lazy way out so I need to decide for sure before I start...
I know I am going to bore you all to tears but I went out and took a look at the bike. It also looks as though on a coaster bike you could mount the motor in front of the frame on the down rod. You could extend the chain a few links and run it over the motor as well as the chain ring. It seems to me that would work just as well. I might go that route as well. I have a spare coaster brake bike sitting around. It's my old three speed converted to a single speed with the small rear wheel. It might be ideal.
By the way I'm sure you all know there is very little drag with an emotor so I should be able to go pedal only or coast without too much problem.
So okay bike people which mount sounds the easiest and has the best change to succeed. I'm gonna take votes here lol.
you'll probably get a sturdier frame if you use an old bike. Those cheap walmart bikes have pretty dinky frames. Something to think about if you're going to weld on it.
Also, are you sure you're going to want your feet to be moving while the motor is running? Seems like that could get annoying after a while. Even if you hook it up like a china kit, it'll charge the battery when it's not in use. I think I would go that way honestly.
good thought but the other side is to conserve battery I plan to freewheel with the motor off except when I am pedaling and to use the motor as an assist to make pedaling easier. I am still up in the air on that one though. It's why I asked for opinions and I do value yours. I kinda feel that way to. I suppose a lot depends on how the engine performs.
What I might do is hook to the seat post with my mount. Then if the chain on the second pully doesn't work out, I can mount the china sprocket. That is a compromise thought.
on the wallyworld bike, I went to the thrift shop today and found three bikes that I can do my own thing to. They are having a half price sale tomorrow, so I hope I can get at least one of them. They should run between five and fifteen dollars. The 15 is for a nice suspension bike like the one I have been working on. It would be easier to mount to one of the solid frames I expect. I'll just have to see what is left when I get there.
I just need the frame I have plenty of wheels and tires that are ready to go. A big butt seat would be nice lol/.
Joe was kind enough to donate a rear sprocket and I ordered a bike chain front sprocket for my motor. I have all the parts to go with my coaster bike frame now. I still might pick up a mt bike tomorrow to try to other mounting technique.
I am trying to figure the approx mph of this ebike setup soooo
what is the rpm of the china motor does anyone know.
a number 25 chain will pull a mountain bike sprocket. I have no idea if it will pull it under power but it seems to fit. If it will work I won't have to weld a different sprocket onto the electric motor. It comes with a 9 tooth sprocket.
So the question for the math whiz is even more important since I can test this puppy pretty soon.
Since the original post I did some checking and the 25 chain is 1/4 x 1/4 the mountain chains is 1/2 by 3/32 obviously it is close enough for deacon work.
I went to the thrift store this morning and they were having their half price sale. I broke down and bought a 26" mountain fury bike. Three front sprockets and probably half a doze in the rear.
The front and rear derailers are frozen but I don't plan to shift it. I plan at the moment to set the motor chain on the large front sprocket. Then a chain from the next smaller one to the largest of the rear sprockets.
I am going to try it with a 12 volt power source first since I want to keep the speed down. If that won't help on the hills then i will go with a 24 volts. The controller should work with either. It will work with 24volts I know.
even though the 25 chain will work I have a bicycle sprocket on the way and I have a slightly smaller motor I can put it on. I think I will give it a try as well. Some combination of engines and power should do the small amount I want. I just don't want overkill. I really do need to exercise some. I just don't want too exercise much lol.
Yeah that where i got mine but the bore is wrong I am going to have to weld it to the sprocket on the motor. Since the 25 chain will work I'm going to try it as well. One of them if not both will work okay im sure.
I thought i had done this post already but I cant find it so here it is again. The thrift store bike was a mt fury I think that is the bottom of the wally mart line. It sure had a lot of cheap plastic.
I managed to save one shifter and one brake set. Everything else was trash. the front wheel was bent and the derailer was gone as well. I ended up with a coaster wheel on the back. I might have to go friction on it, or put bike guy joes sprocket on the rear. I am having second thoughts about pedaling it all the time the electric motor is running.
I'm going to need it to freewheel I think. I did get a lot done so I might just try to original plan tomorrow just to see what it does.
Okay I have the mount welded on and this time it looks like it will hold. I welded it three times as I am still learning. My welds look like tumors but this time I think they will hold the engine.
I have a bicycle chain sprocket on the way. I am going to wait and weld it on rather than mess with the #25 sprocket on the engine. The #25 will turn the chain but it also slips very easily since the teeth are so small. It might shake apart or tear the engine up from my welding but what the heck it is worth a try.
I will add pictures when it is finished no sense going through all the failed attempts to do things. There have been many.
One of the things left to do is to weld the seat in a position from which it will never move. The thing is so worn out that the adjustments are toast. Not the seat on the bike the one from another bike that might not feel quite as strange back there. I'm going to grind and then weld it when it stops raining. Somehow welding in the rain does not seem like a good plan.
I spent the day welding and I'm exhausted. I got the sprocket in the mail from the scooter shop and I welded it onto a motor. I have no idea if it will hold. I almost have the electric motor hooked up correctly. Still have a little alignment to do. Then stick on the other parts. before I do too much more I need to test it to see if it is even feasible. This all might be an exercise in futility.
I'm just too exhausted to mess with it now.