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Old 05-15-2012, 04:28 PM
beastmode986 beastmode986 is offline
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Default have question about engine

well i can get a lawn mower 3.5 hp for 20$ and im wondering if i bought a used cheap bike and mounted the engine so the vertical shaft was rubbing against the side of the tire would this configuration work? i havent seen a friction drive using a vert shaft before so i was just wonder and is the engine to weak????
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Old 05-15-2012, 05:06 PM
CAPTAINCAVEMAN CAPTAINCAVEMAN is offline
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interesting idea but I think you will have a lot of trouble with slipping but I have never seen anything like that
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Old 05-15-2012, 07:02 PM
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I don't see how this would work. If you do manage to make it work post a video please. Best of luck!
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Old 05-15-2012, 07:59 PM
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I thought about this before. Side walls
Of tires are the weekest point with no grip. It would slip and wear tremendously. I wouldent try it unless it can be done cheap.
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Old 05-16-2012, 01:18 AM
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I have read about this idea over at www.motoredbikes.com, and everyone who has tried it has failed. Loke Jake.B says, the sides are the weekens point, and you cant get a good grip

Give it try though, you might figure it out
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Old 05-21-2012, 09:22 AM
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Make an adapter/drive system that drive BOTH sides of the tire. It might work. Some cheap gears from Hardware store might do it.
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Old 05-21-2012, 09:26 AM
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You can give it a go, and I do wish you good luck- but I can't see it being worth the effort. Not enough grip on the sidewall, and too much scrub.
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Old 05-21-2012, 12:52 PM
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just had an idea what if i extend the shaft a bit and put a sprocket or gear or something that will catch the spokes and make the wheels rotate that way?
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Old 05-21-2012, 02:39 PM
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you would just rip the spokes off lol
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Old 05-22-2012, 12:43 AM
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Quote:
Originally Posted by sexyvicta View Post
you would just rip the spokes off lol
X 2. Would be a waste of a good wheel
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Old 05-25-2012, 07:03 PM
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Did you forget about the bit in between the tyre & the spokes? If you put a rubber pulley on the shaft to contact the rim it may work.

I'm surprised no one has picked up on the fact that a 3.5 B&S would weigh more than most bicycles & having it mounted above the wheel would create sever imbalance issues
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Old 05-26-2012, 02:31 AM
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The main problem with side mounting a friction drive system is that the diameter of the wheel is not consistent over the length of the roller, ie at the end closest to the engine it might be 20" but at the other end of the roller its 18", so even if you get enough friction between them for it to work you will still tear up tyres
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Old 05-26-2012, 02:50 AM
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Also bike bearing have no ability to take side load

So if u get enough grip u will just pop the bearing in no time
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Old 05-26-2012, 03:21 AM
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Unless you have a free spinning roller on the other side of the wheel to balance the force.
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Old 05-26-2012, 02:25 PM
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...Which may be true, but still does not address the horrible sidewall scrubbing that you were describing. Furthermore, if the opposing roller is applying enough force to properly counteract the drive roller's sideload, that will add yet more friction and drag.
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Old 05-27-2012, 03:38 AM
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Quote:
Originally Posted by Fabroman View Post
Did you forget about the bit in between the tyre & the spokes? If you put a rubber pulley on the shaft to contact the rim it may work
I think this would be the best idea, especially if you could mount a free running pulley on the other side to clamp the wheel in the middle. I dunno where you could get the little wheels from though.
Edit:
http://www.mcmaster.com/#rubber-wheels/=hpq9y0
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Old 05-27-2012, 07:48 AM
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My only concern about an arrangement like that is friction vs slip. To get the rubber wheel to get a good grab on that rim, the rim must remain clean and dry. I would think a fair bit of pressure would need to be applied in order to achieve a decent grip. That's where you'd get some friction losses.

On the other hand, this IS a friction drive right? Give it a go! I'd like to see a proof-of-concept build here. By putting the engine on a pivot that can swivel in and out, you could accomplish clutching.
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Old 05-27-2012, 03:26 PM
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You could have a few trampoline springs to tension the motor, then get the motor to be pulled by a brake lever with one or multiple pivots to 'gear it down' so the rubber wheel has a tiny gap of a few mm when the lever is pulled.
That could work quite well. After all brkae pads work on the same surface, right?
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