Friction Drives

[trackfodder]

HEY NEAT TIMES ! I think figuring the drive ratio is simpler than you think. The tire diameter on a 26" wheel is roughly 2" less at the sidewall. Assume 24" and a clutch diameter of 4" and it is simple division. The ratio engine to wheel is 6:1, which is a pretty good starting place from my experience with 15 or so homebuilt motorbikes. Take the engine RPM divided by the drive ratio and that is the rpm of the rear wheel. Take the circumference of the tire in inches into inches in a mile (63360)and get rev/min. Multiply by 60 and get RPH. For instance, motor rpm 3000 divided by 6=500 RPM at rear wheel. assume tire circumference as 81.68 X 500=40840.7 in/min.divided by 12=3403.39 ft/minX 60= ft/hr=204203.4 ft/hr divided by 5280 =38.67 mph. That's reasonable. I probably took the long way around, but I had to think it through. KW

 

[Egor]

To figure the ratio for a friction drive, measure the diameter of the roller and figure the distance it will travel for each rotation, it is the same as if it were driving directly on the road. It is essentially the wheel to the bike. The only difference will be if you do not drive directly to the outside of the tire. As you move closer to the axle you increase the diameter of the wheel and it will go farther for each rotation. Have fun, Dave

 

[NEAT TIMES]

I Threw This Tricycle Friction Together Last Month. Simple Easy Build, Works Good. Ron .

 

[starrunner]

I Threw This Tricycle Friction Together Last Month. Simple Easy Build, Works Good. Ron .

I'm a little confused. You say you threw it together last month but the pics are dated Jan 2006 and it looks like a manufactured kit, not a DIY.

 

[NEAT TIMES]

Starrunner, Good Morning, When I Take The Battery Out Of My Camera To Recharge It, The Resets To Default Date. Sorry About That. I Bought Scrap Pieces Of Aluminum At The Sheet Metal Shop And Had Him Bend Them Into Channels For Me. If You Look Close You Might Notice That I Use The Pocket Bike Bell Housing On The Clutch, No One Else Has Done That. Also The Right Side Roller Shaft Support Bearing Is A 2 Bolt Flange Bearing. "bmp" (bikemotorparts) Has A Great Kit, Lowered Prices. 180 Lb Rider, 49cc, 1 1/4" Drive Roller We Get 35 Mph On Flat Pavement, With Pocket Bike 2 Stroke. I Want To Try His New 1 1/2" Composite Roller One Day. And Use One Of My Titan 4 Strokes From Dax. This "friction Drive" Thread Is A Long Running Thread. I Started It My First Day Of Posting On This Forum. Ron .

 

[starrunner]

Starrunner, Good Morning, When I Take The Battery Out Of My Camera To Recharge It, The Resets To Default Date. Sorry About That. I Bought Scrap Pieces Of Aluminum At The Sheet Metal Shop And Had Him Bend Them Into Channels For Me. If You Look Close You Might Notice That I Use The Pocket Bike Bell Housing On The Clutch, No One Else Has Done That. Also The Right Side Roller Shaft Support Bearing Is A 2 Bolt Flange Bearing. "bmp" (bikemotorparts) Has A Great Kit, Lowered Prices. 180 Lb Rider, 49cc, 1 1/4" Drive Roller We Get 35 Mph On Flat Pavement, With Pocket Bike 2 Stroke. I Want To Try His New 1 1/2" Composite Roller One Day. And Use One Of My Titan 4 Strokes From Dax. This "friction Drive" Thread Is A Long Running Thread. I Started It My First Day Of Posting On This Forum. Ron .

I just turn off the timestamp on my camera.
That build looks every bit as good as a bought one and I'll bet it was a lot cheaper. That little lever on the right side threw me off. Looks like commercial. I never thought about it much but I would figure that aluminum channel might break or crack if bent but I guess not. I wouldn't know a pocket bike housing if it hit me on the head. They aren't common sights where I live. Have you had any experience with wet roads? I've heard of someone making wooden drive rollers that supposedly don't slip much. Composite ones would be worth checking out. I've heard some say that their friction drive never slips on wet roads and some say it slips bad, so there must be variables.

 

[NEAT TIMES]

Am just cooling it today after fixing a bad connection in my ac unit . Spent a very uncomfortable day yesterday while it was down, 102* heat index.

So this morning I read thru my original friction drive thread. We have come a long way Baby!! lol

When I joined the forum back in May of 2008 there were approx 100 members!! Now way over 30,000??

I don`t think a pic of my first fd was ever posted, will check my pic files for one now.

Bumped this thread as some member`s mite like to see the evolution that a forum helps provide.

My DIY mount that a local sheet metal shop sheared and bent for me from 1/4" scrap aluminum plate. He bent 3 channels for $40. Have had a lot of favor`s done for me at that shop. When I enter he says; what the h3ll do you want now!! The soft alum does not give a nice clean hole, using hole saw`s like the hard unbendable 1/4" plate does.


You may notice the jackshat hole in the right hand side of the channel, made in 2008. which I never got around to using. On the engine side used a large hole saw for the pocket bike clutch housing, gives much better shaft/bearing alignment and moves the engine in with less overhang. Used the 1.25" od roller with the 1/2" id one way bearing, worked very well.

Bought a box of cap screw shoulder bolts with 1/2" od x 5" long shoulder and 3/8 threads. Drilled the clutch drum and tapped hole to 3/8" theads, on a lath. Replaced the 15mm id housing bearing with a 1/2" id bearing and then chop sawed the allen head off, making a drive shaft for the one way roller.

System will not let me post some pics, I must have posted them elswere. Maybe resize some later.


Ron

 

[cannonball2]

Thanks for bumping the thread NT, lot of good reading!