why I love friction drive

Well I think I have most of the safety issues with the new bike worked out now. Some of the issues were solved with simple mechanical fixes others were procedural changes.

My wife convinced me to switch everything to a larger frame. She said I looked like the bear at the circus on a bike. My test bike is a twenty inch BMX type. No brake lever or gears to shift. Plus my feet will sit flat on the ground should I need to do that. But without the battery trailer it is unstable.

So I made the switch to a 26" junked up mountain bike. It is much more stable.

The cable and lever lift makes it easy to get the motor started then to lower it when I'm moving a little. The procedural change was to just let the motor choke to a stop. I have no idea how bad this is for the motor but I'm sure it's better for me than trying to juggle everything and still get the bike stopped. Once the bike is stopped I lock the motor up while I maneuver the bike around. I can either drag start it or reach around and pull the cord.

I bought a new drive wheel yesterday from the bike shop. I bought a 3/4" diameter axle peg that was drilled all the way through. It is almost perfect for the 5/16 bolt to go through cleanly. There is very very little play around it. The texture is very very deep cuts. It will probably shred the tires. I am considering filling it in with JB weld if it does eat things up.

Pretty much the finished bike. It is a 26" five speed now.

gravity clutch lever.

There were just a couple of things wrong with the bike I built. 1st of all I was wrong about the gears. I really didn't get a chance to use them so I switched to a 24" coaster brake wheel. That works really well. On the 26" bike it lowers it just enough for my short legs to touch the ground but by using the 26" front wheel with brakes and all I had to change nothing at all, not even the kick stand. By going to a coaster brake wheel I got rid of one brake handle and the gear shifter.

So now I have the front brake and the throttle on my right hand side, and a brake lever with a cable to lift the motor off the rear wheel to act as a clutch. I also have a longer throw lever to raise the motor higher and to lock it up so that I can sit and idle at a stop light or sign. I rode it a couple of miles and it seems to do just fine. I need nice weather to really get a test ride in.

Okay now that I have the motor attached, the lift cable working, and the controls manageable, I have turned my sights to better drive wheels. I bought a couple of heavy testured axle pegs that should have been the cats meow, but (there is always a but darn it) they are alum and in a week have significant wear showing.

I have started an experiment with old bicycle tires cut and attached to the drive wheels with contact cement. I'm going to let them rest a couple of days then try the one I am starting with. I have attached the tread from a bike tire to a deep socket. I will let you know how that works out. I have a couple of other options based on variations of that idea.

Another idea I have is to make my own drive from hex nuts. That is my next project if the one I'm working on now is a bust. Oh yeah we used jb weld and sand back in the day. That might be a good coating for the deep socket if the tire tread pulls off.

There are lots of things to try. My first choice would be some kind of wheel, since the wheel on a wheel works so well on my ebike.

If you can find a thread by sensible shoes on her weed whacker build from about a year ago, I think it had the best no weld mount I have ever seen. Unlike all my builds with weed whackers. she was able to keep the case and therefore keep it cooler than I could.

Today I gave my homemade drive wheel a try. This one I made from a spark plug socket. I roughed it up a bit then I contact cemented the tread of a bicycle tire to it. I wrapped it in electrical tape for three days to let the cement cure. Not sure what the optimal time is but I had time to spare.

I left about an eighth inch crack where the two ends of the tread met. when it was dry I filled that with jb weld and let it sit a couple of days. I tested it today. The test was only a mile (its cold out there) but the wheel did well and wasn't significantly damaged. Some of the tread wore down but not much. It needed to anyway. One thing I was glad of was that I had a brake lever lift on the motor. I had to vary the tension to get good performance.

I'm looking forward to more tests to see how it does.

Yes I got my adjectives mixed up sorry. One of the best WW builders I ever saw on the forum. Too bad she stopped coming around.

Okay I built a new drive wheel for the bike. I also had to redo the lift system last night but that is cool now I think. The one I had covered came apart as I expected that it would. I had hoped that it wouldn't be it did. I made the new drive wheel from 3/4" steel hex nuts. Inside those I put 3/8 hex nuts to keep them from move around too much. Then I slid the 5/16 bolt that attaches it to the motor through the whole mess. I used some lock washers to hold it in place so now I need to test ride it. I hope it will do the trick. If not I have a 3/4" pipe nipple in mind. I have used those covered with jbweld and hobby sand as an abrasive. They work pretty well actually.

It isn't so cold right now, so I tested the new drive wheel. I have to admit that it worked really well. I don't know how long it will last before it distroys the engine, but at the moment it is working pretty well.

So let me detail what all this diy friction drive has.

First of all it had kit engine and mount of sorts. The mount is very much what I have built without a kit. It is pretty much what we all used a hingle with the motor attached, One thing that is different and much better than what I built before is the hinge system. It is way thicker than anything I ever made. It makes the whole thing rigid beyond anything I built and thats a good thing. It isn't perfect but it works really well.

I started out with it on a 20" bmx type frame and it wasn't very effective at all. As a matter of fact that is what threw me. So I went with a 26" huffy mountain bike with somewhat screw up gears and such. After experimenting. I swapped the gears for a coaster rear wheel. I did it mostly for the brake for the brake, since it is very hard to change the gears on a friction drive bike. I mean there just is no need for them. You just need the highest one there is. I just had too many levers on the handlebars, so the wheel swap got ride of the gear shifts and one brake lever.. My throttle is on a brake lever, so is my clutch (engine lift cable) I have no gears on the bike but I am using the largest front chain ring with a coaster chain and rear wheel. It works fine and hasn't jumped yet.

I do have a front brake with a lever. I wouldn't want to ride a power bike with only one brake. The front wheel is a 26" and the rear coaster is a 24". The bike is reasonably easy for me to mount and dismount which is also important since i fall a lot trying to get on and off bikes. I have a metal egg basket on the front in which I will carry extra gasoline. I also have about a two inch spot convex mirror mounted onto the side of the handlebars.

The so called kit I bought ran fine, but it had some things wrong after the fall. The gas tank for one thing leaked. It leaked around the fuel lines. I had some extra lines but they were all for weed whackers and the carb on this motor wasn't the same. It had bigger lines, so the holes in the gas tank were larger. Since I had a bunch of weed eater motors I have screwed up. I robbed a tank and lines from one. It was a close enough fit so that I could swap it out. I had to force the gas lines on but they seem to work without leaking.

I believe that this one is finished, unless I tinker with the drive wheel some more. The scissor hinge works beautifully as a clutch. One quick observation even thought the nuts on the drive are 3/4" they most like are over an 1" at their widest outside points.

when i think i have it set up, I find something I dont like. Some of it is me and some of it is the nature of the beast. My ebike pulls better but it has crappy range. This one is going to go really far but lacks the torque of the ebike. Top end speed is comparable but the other two factors vary widely. Most likely the motor on the bumble bee kit I have was something under 33cc it runs like it might be 30 give or take a couple.

Where I want the power is on the hill. I don't care so much about the flat speed. I'm going to tinker with the drive wheel to get the max bang for cc but I don't expect much. The best torque so far has been from either a 3/4" outside diameter axle peg big time roughed up or a fairly smooth 1/3 inside diameter steel pipe. My only concern with the axle peg is that it is aluminum and has worn down already in only a week. Tomorrow if I don't forget, I'm going to build something similar from steel. One at 1/2' ID and one 3/4" Id.

I have struck a milestone. At least at this moment I know what this bike is capable of at the minimum. I got the tension right... I got the drive wheel size right... I got the throttle linkage adjusted right. and the bike sings. It will do between 15 and 20mph on the flat. It will climb a hill as well as the ebikes which is all I wanted it to do.\

There are a couple of things that I might still do to the bike frame part of the build. but I doubt it. I could drop the chain to the smaller of the two front chain rings and make it easier to pedal up those long hills I have here, but I would sacrifice the ability to keep the speed up on those same hills. Not sure which would be better. I'm going to ride it a while with this new configuration before I make any changes.

If you have followed this thread, you know i have pieced together a bike using junk and spare parts. Then stuck on the half ***ed kit from a failed company. It ran okay at first. I adjusted it and changed all the basic controls and it ran a little better.

Yesterday I thought I finally had it all adjusted really well so I took off on a four mile ride to the hardware store, It did really okay going there, then coming home it started to do really, really okay. By the time I got home it was doing raally well. I couldn't figure out why it started to do better for absolutely no good reason. Then I noticed the excessive wear on the knobby tires. The drive wheel was only hitting rubber about 65% of the time until those tires wore down. Now for at least a little while it will rock.

I also had to move the chain to the smaller front chain ring as I expected I might eventually have to do. The chain came off because the chain ring keeper is a piece of plastic about as thick as a disposable plastic picnic plate. Now I can pedal the bike when I start off but after that it is all motor. It doesn't ever get slow enough for me to catch the free wheel, which is fine by me

The drive I used last was a 3/4" id pipe nipple which was all threads. I used it five miles maybe and it is doing a number on the tire but it runs sweet. I made a drive this morning from 1/2" id hex nuts. I have them epoxied together now drying. Probably by tomorrow I will be able to test them. The epoxy is just to keep them together until I run a bolt through them then into the drive shaft of the motor. I know that epoxy won't hold them but it will keep them aligned until I can get the bolt tight enough to hold them in place. At least that is the plan.

just in case some other foolish person wanted to build the easiest friction drive possible, I thought I would show how the lift clutch works.. So here you go.

Note the scissor hinge is not more than to long pieces of fence tensioner one is hooked to the frame of the motor and one to the frame of the bike. S spring is used between the motor and frame to keep tension on the drive. A cable is run between the attachment point of the two pieces and the front of the bike.

Pulling the brake lever shortens the cable pulling the hinge forward and lifting the engine. Effectively it is a clutch.


even though the rear wheel is a coaster brake, I added a front wheel pull brake always a good idea. the shifter control is now my throttle control. a little cleaner looking than two brake levers even though it worked really well. I never got confused.


drive wheel is a couple of hex nuts

Do you know what the cc of that motor is. I'm real curious about that. I thought that I remembered someone using the boat roller as a drive wheel. The best thing about this motor is the fact that a 5/16 bolt attaches any drive roller to it. I wanted to try the bolts because they have the more or less same design as that ebay kit with the bars on the rollers. I'm curious to see how that does on knobby tires.

I will keep the fact that you have one of these motors in mind. I am actually thinking now that with the mount the way it is on this bike at the moment, I could life that small greyhound motor should this one go south on me. That would be one **** of a friction drive engine.

after some more tests on the bolt drive wheel, i went back to the pipe nipple with jb weld in the threads with a little hobby sand sprinkled on top. It actually seems to work the best so far. I know it will have minimal wear compared to the alum axle peg it was the worst so for. I have not tried plastic yet but I like the idea of the plastic slug which is what some of those guides look like. I also have not given any consideration to the wear on the tires. For now I'm enjoying the freedom of having the extra range not provided by Ebikes.