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Old 06-24-2011, 12:47 PM
ryan51173 ryan51173 is offline
Motorized Bicycle Newbie
Join Date: Jun 2011
Location: usa
Posts: 1
Default New and need help.

Hi Everyone,

I just started my bike the other night and got pretty far. Came up with my own prefab mounting kit. The question I have is .....How much pressure should be on the tire from the spindle? Currently I have a peice of 1/2" black iron (gas pipe) attached to the shaft/spindle. That is rock solid and holds. My rear tire is knobby and could be part of my problem. The more I crank down my setup it's almost impossible to pedal and still have some slipage. Now my friction drive is tiliting on angle due to having it cranked down so much. So, I added a side attachment to even out the spindle. I'm concerned I might burn something in the engine with this much downward pressure!
What could the problem be?
Knobby tires? Smooth spindle? Tire pressure? Is there a measureing guide on what the correct downward pressure should be?
Every video I've seen the spindle hardly looks like it's pushing down on the tire.

to note:
I was only able to crank over the engine once on the bike. Any suggestions would truly help.

Ryan (newbie)
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Old 06-24-2011, 12:55 PM
Al.Fisherman's Avatar
Al.Fisherman Al.Fisherman is offline
Motorized Bicycle Elite Member
Join Date: Sep 2009
Location: Calera, Alabama
Posts: 1,966
Default Re: New and need help.

What the heck are you working on. A picture or two sure would help. Do you have any idea how many different kits and engines we all put on a bike.
Looking for HT's parts?
HT pre instillation tips.
Engine running problems?
HT breakdown Photos

Ron ><)))))*> Calera, Alabama
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Old 07-06-2011, 05:25 PM
oldguy387 oldguy387 is offline
Motorized Bicycle Member
Join Date: Jul 2011
Location: Bethlehem,Pa.
Posts: 31
Default Re: New and need help.

Ryan - If you are talking about the bottom bracket, I think I can understand somewhat as to what you are talking about. As Al said, some pics. If you are talking about chain flex between crank set and chain set/cogs, there is not a written rule.
"I've never been an expert at anything, but I sure do meet alot of them on a daily basis" My Quote

"Any club that would have me for a member I wouldn't want to join." Groucho Marx
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Old 07-07-2011, 01:09 PM
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rohmell rohmell is offline
Motorized Bicycle Elite Member
Join Date: Jun 2010
Location: New York
Posts: 1,533
Default Re: New and need help.

Better to have a bearing on each side of the spindle.
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Old 07-07-2011, 04:02 PM
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MarkSumpter MarkSumpter is offline
Motorized Bicycle Elite Member
Join Date: Nov 2010
Location: Ohio
Posts: 474
Default Re: New and need help.

As stated pictures would be a big help in diagnosing your issues but from what I gather by your post you are trying to make a friction drive. Correct?

If so knobby tires and a piece of slick pipe are going to barely give you enough surface tension to drive the bike without slippage (which will cut the tires down fast) let alone if you are trying to bump start it. If this is the case you are better off pull starting the engine.

And as Rohmell said it is always good to have as much support as possible on both sides of a shaft. And you are also correct that if you exert too much pressure for long periods of time on a shaft you can expect to have bearing / bushing and seal issues in short order.

On a side note no matter how you are designing your drive if you are using clamps on an aluminum frame you should make sure to put a piece of steel (like a partial section of EMT conduit) between the frame and clamp to distribute clamp pressure over a larger area to avoid serious frame damage.
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Old 07-07-2011, 10:38 PM
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Vistaman73 Vistaman73 is offline
Chat Box Junkie
Join Date: Nov 2009
Location: Shawnee, Kansas
Posts: 247
Default Re: New and need help.

no response in over a week, i dont think he's coming back. another one of those people....
They call these Power Assisted Bikes....Wait, who's assisting who? Last time I checked, I spend twice as much time in the garage working on it than I do riding it! Vista Out.
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