60cc BMX with Vertical Shaft Friction Drive

Whats the HP of the engine? Im running 2" rollers on my 2.5hp Lifans Good combo of speed/hill climbing. Looks like you have 5hp? you can pretty much run what you want with that. Just figure what you want for a top speed.
 
could be a 5hp?, but is that possible over only 60cc? Could be a 3,5hp aswell? Not sure how to find out..
Looking more for a constant amount of torque, I live in a valley, so there are hills in every direction..
 
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Thats gotta be more than 3.5hp Its OHC isnt it? Is it a Honda or a a clone of one? Any way, rpm is the determining factor on top end. I would guess if ungoverned 4500 is reasonable. A 2" would give 26.8mph, 2.25" 30mph. I would think with the HP that engine has either would climb well.
 
Vlam

It could very possobly pull a 3 inch diamiter roller if it is 5 hp. You may want to be sure your motor can slide far enough for the different size roller`s. That will be a great and fun ride for you.

If you make your own roller simular to Cannonball2 method, you could shape it by running the motor and using a very coarse wood rasp to closely fit the tire side wall contour. That probably will not be necesary though.

Cannonball has more experience than me with the roller size. I have a 25cc Zip Cycle that came with a 2.5 inch friction roller, but it runs a jackshaft for gear ratio. I prefer peaceful lower rpm when it will work.
 
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Cannon, is there a calculator program or formula for speed/roller size you could suggest?

I know some one posted the math, but forgot to save it.
 
VlamBallas said:
Hmmm, I shall investigate further. What size roller would you recommend?
Click to expand...

I used 3" dia steel 45 deg cones with an old 3.5 briggs. It would do about 30mph governed. Plenty of torque and power at lower speeds too.

Maybe 30 deg cones. would wear the tire less than 45 deg ?

Larger dia is better for less tire wear with the 90 deg friction drive.
 
Seems ive got a 5hp OHC motor, honda clone. Found the exact same mower at the mechanic round the corner,. Also found some shweet 1inch rubber mat at work. Will be perfect to make a roller from.
I dont think a serious top speed will be the best idea on a bike this small, from what ive seen here, I reckon a 2" drive roller will be the best option? Should get me a decent speed, and more than enough power to get me where I wanna go..

Gonna have to invest in some proper brakes, no use having a power house on the back wheel, and not being able to stop it...
 
The 2" should be fine, will top out around 28mph@4800rpm, cruise very nicely around 23mph. Climbing power will not be a issue with 5hp. I you have any questions about assembling the roller, just ask.
 
Picked up my wheels today, didn't really focus. Bought a set of knobbly tyres, sigh. So gonna have to tune the roller a bit to make it work, if that fails, think I can tune a bit off the tyre too.
:-||
 
Vlam, good brakes are a great idea. I like to think of them as "get out of trouble almost as fast as I got in it" snork

Cannon, thanks big time for that link. Was playing with it last night. Perfect!
(that thing we had been talking about will have a theoretic speed of 41MPH. TY again)
 
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If you use a cone roller, you will need about 3 " dia to get the tire's center of contact at about 2 " dia

Lotta extra wasted friction with the cone roller,with the twisting motion. This is less so with larger rollers.

The mower engines are governed to 3600. Plenty of power for a FD bike, I wouldn't disable the govenor.
I would start with a 3 " minimum dia for a cone drive, and maybe 30 deg drive cone instead of 45. Heck, make the motor adjustable side to side and start with a larger cone.
 
Late comer to the thread but a couple of ideas. Instead of driving on the sidewall why not drive on the rim? I know it may slip a little more, but it would hold up better. And are you going to hinge it vertical or horizontal? I know weedwacker FD hinge vertical (up and and down) but if you hinged this Horizontal (left to right) you would not have to fight the weight of the motor, just the tension of the spring that pulls the roller into place. Just some thoughts I have had while debating a new lawnmower so I can use my old one for such a project.
 
The motor slides horisontally (left to right), with a standard roller, a cone wont work to well with the knobblies. Have thought about having the roller run on the rim, Using a decent rubber, so it shouldn slip too much. It will surely solve the problem of having to change the roller in order for it to grip the tyre sidewall.
Though there aint much rim to work with, Will also need to check if the motor shaft is long enough to reach through the engine mount and down to the rim..
08062011.jpg

Thanx for the idea, Will give an update onn the situation soon a I get home.
 
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Vlam

The tires and wheel look tuff. When you stated motor slides left to right

I just thought I would mention something you propably already know. You have to drive the

wheel on the right side with the roller (pedal chain side). Unless you like going backward.
 
Contrary to popular belief, riding backwards is the latest trend in bicycling, The more you ride the less your mileage gets. lol
but the engine mount can be swapped around either way, Guess I'll go double check the engine rotation direction just to be sure.
 
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My experience with the rubber roller is that its very tolerant of tread designs, Slicks, cruiser tires, MTB tires all drive equally well. Granted I havent tried a block tread like you have, I see no reason why driving it would be a problem. What I am working around to saying is since the rubber roller is so easy to experiment with(make) I would just pick a size and try it. I am sure it would have no trouble driving the blocks on the side wall. My bet is it will soon conform to the side wall, unless you are using something super hard. Mine are horse stall mat(what I had laying around) and I assume on the softer scale. The one now approaching 300mi has slightly conformed to its tire. Pics are in the roller thread. Give it a shot, you really have nothing to loose. There is precious little area on the rim, and yes even though brakes grip it fairly well the pressures are far greater.
 
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