Second build... Friction drive.

gasser

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Apr 9, 2009
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So, I built a chinese MB and wasnt please with the engine at all. Then proceeded to buy an old solex velosex and was really a sweet little ride but uber gutless. I used to race gopeds and have quite a bit of knowledge building them and can biuld a 5hp motor pretty easily. So now im thinking about strapping one of my motors on the front wheel of an old cruiser. What are the drawbacks of a friction drive? What should I watch for? anyone else build a "high horse" friction drive?
 


Esteban

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Dec 1, 2006
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Friction drives, like all driven bikes, have their positives & negatives. I like them & they are probably the oldest form of adapting a motor to drive a bike. A pix from a friend's bike is attached. The biggest thing I like is you can choose from several great & reliable engines for them. You don't need a big, powerful engine on them. I would suggest reading ALL of this long thread to see some bikes before starting your project.

http://www.motoredbikes.com/showthread.php?t=4770
 

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5-7HEAVEN

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Enter "The Dragon Lady"

I own a high horse friction machine. Dual 2.2hp 43cc Mitsubishi engines, one on each tire. Twin ADA S1 expansion pipes, WYK-58 Walbro carbs to be installed next.

Maybe tw0 5hp GP460 engines on friction drive in the future. Shhhh:devilish:

If using only one engine, install it on rear tire. Handling at walking speed suffers with front drive.

A front engine mount might be difficult to install if you have a suspension fork.

Be sure to route the exhaust to the side, not in your face.

The front expansion pipe's exhaust blew directly in my face. I rerouted the fumes with a 39" long rubber exhaust tube. The smoke exits below the crankset. The tubing muffles the sound so well that I disconnected and removed the silencer.

Old cruiser? To go fast you need to stop fast, often and with no brake fade.

I have a girlie cruiser frame with coaster brake as well as front and rear side-pull vee-brakes.

Positives include the simplest drive with no chain breakage or alignment.

Negatives are slipping tire engagement on wet roads and tire wear. Certain friction kits have rollers which are a bear to swap out.
 

gasser

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Apr 9, 2009
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If using only one engine, install it on rear tire. Handling at walking speed suffers with front drive.
Im pretty set on mounting it on the front wheel. I didnt mind it too much on the solex and to me is much more aestheticaly pleasing.

A front engine mount might be difficult to install if you have a suspension fork.
Im leaning towards a dual crown rigid fork.

Old cruiser? To go fast you need to stop fast, often and with no brake fade.
Thats one of the aspects I havent decided on what to do.

Negatives are slipping tire engagement on wet roads and tire wear. Certain friction kits have rollers which are a bear to swap out.
hmmm, thats one thing ive worried about was slippage. How are you guys over coming this? Ive thought about machining a contoured spindle similar to the old proline spindles(pictured on engine) but with deeper grooves. Also running a spindle support bearing so i can apply more pressure without harming the spindle. I live in oregon and rain is definatly an issue. Not so much worried about tire wear.

engines.jpg
 
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Alaskavan

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I rsolve the slippage problem by not riding the friction drive in the rain.
 

gasser

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Apr 9, 2009
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We have a saying here. "If you cant ride in the rain, you dont ride."
Maybe friction drive isnt the way to go. hmmm...
 
A

Alaskavan

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Pretty much the same weather here (maybe a little colder). That's why my second and third build are chain drive.
 
5

5-7HEAVEN

Guest
hmmm, thats one thing ive worried about was slippage. How are you guys over coming this? Ive thought about machining a contoured spindle similar to the old proline spindles(pictured on engine) but with deeper grooves. Also running a spindle support bearing so i can apply more pressure without harming the spindle. I live in oregon and rain is definatly an issue. Not so much worried about tire wear.

engines.jpg

You could knurl your roller, diamond hatch pattern.

Like I said, coaster brake plus front and rear side-pull vee-brakes.
 

gasser

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Apr 9, 2009
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You could knurl your roller, diamond hatch pattern.

I might just have to make both and see what works best:devilish:
I know on gopeds the knurling just ate the **** out of tires compared to the ribbed rollers and the ribbed didnt seem to suffer from traction. but Im sure things are different with pneumatic tires and not solid rubber one. Turning out a knurled roller would be a lot easier than a contoured one thats for sure!
 
5

5-7HEAVEN

Guest
Staton makes rollers with diamond pattern.They absolutely grip the tire without eating them...unless your tire engagement is out of adjustment and the spindle is slipping..

Then it'll immediately start to grind your rubber tread.

As a New Year's resolution I am totally committed to riding my bike to work on a daily basis, rain or shine. On the days that the roads were wet it was still possible to ride with friction drive. Of course more pedalling is involved and ya have to find the engines' "sweet spots".
 
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