Weed Eater Friction Drive Bicycle

[landuse]

I have been having some withdrawal symptoms since I finished my minibike, so I have now decided what my new project is going to be. A friction driven weed eater bicycle!! I have already gotten started with the whole project.

I have decided to use an old Mitsubishi T50 engine that I got off a trimmer. As far as I can tell, it is a 26cc engine. I just hope it has enough guts for what I am going to use it for. I also decided to be a little more elaborate than your average back yard friction drive that you see on the net and on YouTube. I have decided to try and duplicate the Staton/DAX friction drive setup.

So far, I have cut the steel plate into 3 equal sections and welded them together to make the U shaped housing that everything is going to bolt to. I then measured the bolt pattern of the clutch housing for the motor, and drilled the holes for that. Due to the rotation of the engine, it is going to be mounted on the right hand side of the bike. (I hope I got that right).Trying to get it all not to warp too much was difficult.

I then cut lengths of steel strips and welded them together for the U bracket that bolts onto the bike frame. As a protection for the bike, I cut strips of rubber off an old car mat and drilled holes in that to fit my bracket.

I am going to have to use a contact I have at a machine shop to drill out the holes in the housing for me to fit the bearings into. He is also going to machine the steel bar I have into the roller that will attach to the clutch drum. He only opens shop again tomorrow, so I will get hold of him within a few days.

Well, that is where I am at the moment. I have included a few pics of everything mocked up together.

 

[r97]

Nice work so far, that little box turned out pretty nice! I have a similar engine that I have been thinking about setting up on a bike for a while now, will be fun to see something similar working. Good luck!

 

[Doc Sprocket]

Looks like a pretty good start- I see you got one of the "better" weedies with a clutch. Are you going to knurl the drive roller, or use some other method of adding friction?

 

[souperman000]

What do you mean by a "friction driven bicycle"?

 

[landuse]

Nice work so far, that little box turned out pretty nice! I have a similar engine that I have been thinking about setting up on a bike for a while now, will be fun to see something similar working. Good luck!

Thanks r97

Looks like a pretty good start- I see you got one of the "better" weedies with a clutch. Are you going to knurl the drive roller, or use some other method of adding friction?

I am definately going to knurl it. I was thinking something like parallel lines cut into the roller like the pic below.

What do you mean by a "friction driven bicycle"?

A friction drive bicycle is one where the bicycle isn't directly driven by the motor through the use of chain and sprockets. A roller is used that puts pressure on the rear tyre. When the engine spins, the roller will then "spin" the tyre as well. This method is not as efficient as using chain and sprockets, and a lot of the enrgy of the engine can be lost due to slippage, but it is pretty decent.

You just have to watch how you ride the bike. You generally cannot just take off from a dead stop using friction drive (unless you have a really strong engine and you start really slowly). You usually have to pedal a bit to get your speed up, and then open the throttle. Wet weather also means major slippage, but who is really going to ride in the rain.

One thing I learned about gearing with friction drive, is that the size and diameter of your tyre has absolutely no influence. It is the diameter of the roller that is important. A smaller diameter roller is like gearing high, and a larger diameter is like gearing low.

I am just going to have to wait and see how my engine performs. I just hope it is strong enough. I weigh about 180 pounds, so I am not that light.

I thought I would add some pics of me making the box channel as well.

 

[landuse]

I got a little more done this weekend. I cut the 2 lengths ofmetal strips that will be attached to the U channel and to the sprocket area to tension the roller against the tyre. (I am not sure what they are called). I had to cut slots at the top of each so that I can tension the channel easily. I had to do this with a grinder again, so it doesn't look too pretty.....but it will work. When I went to the scrap metal yard a week or so ago, I also came across a mechanical drill press that you put your hand drill in. I didn't have a drill press cos they are too expensive, so I got this one for practically nothing. It works great!

 

[landuse]

Yesterday I handed over my U channel to a machinist to drill the holes for the bearings and machine a roller for me. Because I am small fry business for him, I might have to wait a little bit before he gets the time to do my work. I will keep you all updated though on the progress.

 

[bighead]

withdrawal symptoms do you? LOL I totaly get it friend. Nice work.

 

[landuse]

Well.....I was given a brand new Ryobi 30cc engine last week. I have decided to make another friction drive out of this one, and maybe hold off on completing the one that I started this thread with.

I have already done some work to get this one off the ground. I will be drag starting the engine, as I couldn't find a way of putting my bike peg on the shaft without removing the pull start. I have decided to make a simple bracket, that will pivot on a U shaped bracket attached to the frame. I will weld 2 strips of metal to the frame so that I can bolt the engine on.

I am going to be using turnbuckles and springs to tension the motor onto the wheel. I still have to weld up the U bracket for the frame, and buy the correct springs. I am going to have a look at springs today. It might take me a few tries to get the correct ones.

Here are some pics of the setup I have so far.

 

[hodala]

not exactly know "Weed Eater"means,does the bike go through long weed field,roller&tyre crunch Weeds in?is that your DIY just for fun?
I heared my sister said, South Africa no easy shopping(to find work shop for machining) everywhere,she's husband a citizen there,but immigrated many years ago to Singapore

 

[landuse]

not exactly know "Weed Eater"means,does the bike go through long weed field,roller&tyre crunch Weeds in?is that your DIY just for fun
I heared my sister said, South Africa no easy shopping everywhere,she's husband an citizen there,but immigrated many years ago to Singapore,

A weed eater is a machine that cuts grass. It looks like the one in the picture. I am putting it on a bicycle so that I don't have to pedal .

Shopping here is not bad. It is not like America where you can get anything you want for cheap though. There are practically no internet shops to buy things.

I have also included a pic of a weedeater on a bicycle.

 

[hodala]

A weed eater is a machine that cuts grass. It looks like the one in the picture. I am putting it on a bicycle so that I don't have to pedal .

Shopping here is not bad. It is not like America where you can get anything you want for cheap though. There are practically no internet shops to buy things.

I have also included a pic of a weedeater on a bicycle.

I only know grass trimmer and branches eater
15 year ago had also developed a trimmer engine drive bicycle with CVT,no success in market
the dwg picture several years ago design,2 speed automatic,not even try to build prototype

 

[landuse]

I only know grass trimmer and branches eater

A grass trimmer and a weed eater is the same thing. We just call it another name.

 

[landuse]

OK, so I pretty much finished my bike this weekend. There are one or two things that still need to be done like fixing the kill switch to the frame, and neatening up some of the cables. I also have to do the scissor clutch, as I didn’t have time to do it this weekend.

I first welded the metal strips I am using as a motor mount to my frame. It was a bit of a pain to get everything lined up, but I got it done in the end. I also fixed my frame to the bike, so everything was lined up. I then mounted the engine, cut some grooves in the foot peg, and added the springs and turnbuckles.

The springs worked better than I had hoped. I had bought much longer springs originally thinking that the whole frame would sit higher than what it does, but fortunately I had the shorter ones lying around. I just drilled a hole on either side for the spring to hook onto.

On Saturday I went to our local bicycle shop, and bought some more brake levers for my throttle and clutch. I mounted then on the handle bars opposite to what they should be, so that I could operate them with my thumbs. I had also bought some cheap brake kits, so I had a few pieces that I could use to set the accelerator up. I took a pic of where I connected the two cables. I hope it works out OK.

I lengthened the kill switch, so it reaches the handles now. I must just buy some more zip ties to neaten it all up. By this time it had started raining, and I wasn’t able t take it on a test run, but this evening when I get home (if it isn’t raining) I am going to give it a run.

 

[landuse]

I was all exited when I got home last night to try my bike out. I hopped on, started pedaling with the choke on till it wanted to start and then took the choke off. It started fine, but I just had no torque at all. It was really dissapointing. When I turned round at the end of the street to come back home I had a bit of a downhill, so that went fine.

When I got off the bike and had a look at the motor, I saw that the roller had come loose, and could rotate on the motor shaft a bit. This was probably causing the terrible torque. I think the roller is also too big for my motor. It is a 1 1/2" foot peg. I think I might try something with a smaller diameter.

I also smelled something like burning rubber, but it wasn't the tyre at all, it was the engine. I also saw a wisp of smoke come from the engine. Do you think that the loose roller could have overheated something on the engine to make that smell. The tyre still looked good.

Do you think there is enough air flow round the engine with the engine covers like they are. I cut the front off as you can see.

It was a dissapointing first run, but I will get her right soon.

 

[kaymo]

no telling about enough air since the fan no longer works without the cover...

 

[landuse]

no telling about enough air since the fan no longer works without the cover...

I am not too sure what you mean by the 'fan'. All that I cut off was the section that housed the recoil starter. All that was in there was the recoil assembly.

 

[sexyvicta]

he means the fins on the flywheel. But yeh nah they go fine without the cowling. I chopped all mine off. I've ridn mine for maybe 30 mins non stop and its no problem.

-edited due to me no looking at pics properly.

you will need to loctite the crank bolt on. Mine kept undoing until i did that. As long as the spindle is centred its ok if the centre hole isn't a tight fit. I think maybe as you're coasting and the wheel is pushing against the engine it loosens the nut.

throw that chinatown ryobi in the bin anyway and put the mitsubishi on

^no cowling in front of fan so you may aswel remove the rest of the plastic as it'll just be keeping the heat in.

 

[sexyvicta]

oh yeh and use your peddles to help the engine until you're going fast enough if you've geared it too high. Mines only like 1 inch or something but my engine is smaller and even ****er than your ryobi

 

[landuse]

Thanks sexyvicta. I only kept the cowling so that it looked nice. I am going to have to rework the spindle, cos the retaining nut that you can see in the end of it did not come loose. I had used loctite to keep it in. I think some of the spacers inside shifted a bit.