Spring loaded tensioner questions

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biknut

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Sep 28, 2010
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This is how I did it.Kip.
Thanks for those nice pictures. Looks like you did a really good job. It's funny, this morning before getting up I was laying in bed thinking about drilling my frame and running the wires through there.
 

kipharley

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Jul 9, 2009
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Oh Oh! You were,nt supposed to look there!Just at the tensioner! Just "Note" I do not recommend doing any thing I post.I'm just showing what I do.Kip.
 

biknut

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I have my chain installed now (no tensioner yet). I cut the chain as short as possible, and still be able to get the master link together. There's almost 3" of travel in the middle run of the chain. Is something wrong?

I can't move the axle back any further because the peddle chain is tight.



 
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biknut

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I found a bicycle store near my house that has 415 half links. I'm thinking I have enough slack to take one more link out and use a half link. After that my chain should be pretty close.
 

2door

Moderator
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Sep 15, 2008
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I'm a little confused, biknut. Are you planning to use a tensioner, or not? If you are then the slack you have now can be adjusted out by any adjustment in the tensioner. If you plan not to use one then you'll need to shorten the chain more and maybe also adjust the pedal chain. This is where running without a tensioner can get sticky on a single speed bike without adjustable drop outs. Good luck, let us know what you come up with.
Tom
 

biknut

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I'm a little confused, biknut. Are you planning to use a tensioner, or not? If you are then the slack you have now can be adjusted out by any adjustment in the tensioner. If you plan not to use one then you'll need to shorten the chain more and maybe also adjust the pedal chain. This is where running without a tensioner can get sticky on a single speed bike without adjustable drop outs. Good luck, let us know what you come up with.
Tom
I thought we decided that with a spring loaded tensioner I need to limit the slop to 1/2" to 3/4", and the tensioner takes up the rest?

I don't know if that's going to be possible to get the chain that tight or not without adjusting the axle. Today I found a #41 half link which I'm told will work with a 415 chain. I'm going to try this next. I know it'll be a lot tighter.
 

Fulltimer

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Aug 13, 2010
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With that length of chain you won't be able to get all the slack out. Gravity & weight will make it sag in the middle. Use a tensioner. Even with that you will have some sag but that is okay as long as it isn't more than an inch.

Terry
 
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biknut

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I'm not sure I'm understanding about the chain. Right now if I measure the deflection of the chain in the middle of the run between the sprockets, there's almost 4". But the length of chain it would take to go dead tight is less than an inch. If I remove one link, and install a half link it looks like the chain would then be too short by at almost 1/2"

What that seems to be telling me is I can't shorten the chain anymore.
 

Fulltimer

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Look at it this way. Take a 10' long steel pipe, set each end off the ground resting, say 1 foot high. The pipe will bend in the middle also. If you shorten the pipe it won't reach the resting points will it. If you add joint every foot it will sag even more.

You can't get it perfectly tight and I don't think you would want to anyway. I'm pretty sure that you would ware out the chain or sprocket or maybe both faster than you would if there was slack.

If I'm wrong someone please correct this.

Terry
 

corgi1

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Aug 13, 2009
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if a rope was run through the rear wheel and the bike suspended in a such a way to apply tention to the lower chain run as it was hanging nose end down from the ceiling,then connect the chain on the upper run as snug as possible by hand,at this time you will only be livting a 12 inch or so piece of chain to make the connection and all excess play suould be held tight with the rope and motor compression,that is as tight as is expected and the idler and spring idler may or may not be needed it is mainly to clear the chain stay on narrow problems,,, ,and to avoid chain wipping ,the teeth on the sprockets need to be beveled correctly and sprokets aligned properly to eliminate chain occilation which acts like a bearing slide hammer on the little components

the motor needs to be mounted in a way that there is positive ,absoluty no play,frame contact not dependent on the little bolts to do more than look nice holding parts in place, not act as 5/16-3/8 ths muffler clamps forcing things to bend into place to hold
 

biknut

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Sep 28, 2010
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This is what I decided to do. I started thinking that with this much chain slack maybe a spring tensioner won't work. I'm afraid the chain might try to jump the sprocket on deceleration. i used the stock tensioner. The price was right anyway.

I'm not 100% sold on this idea. Call it my first prototype. I seems to get the job done, but the whole shabang is mounted on 2 little 6mm motor mount studs.





 

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corgi1

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I'm sorry to disagree ,,, I would be afraid of mounting it on the little motor mount bolts ,the twisting action when droping the clutch to start the motor will be a lot of pressure against the motor mount bolts and may break them,
 

Dan

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May 25, 2008
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Just a thought. I think we have all contributed to over complicating this to the point of gigundo crazy. Chain has to be tight enough to not slap. Loose enough to do no harm or bind. Put it on and if it can wiggle' a lil, good 2 go. When it wears in, tighten it up a wee bit. Forget the MMs, inches or torque per naqromeeters.
 

Dan

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May 25, 2008
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Just another thought, Corgi is right. Thats a lot of stress at a bad angle. Might want to beef it up.
 

biknut

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Sep 28, 2010
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I'm sorry to disagree ,,, I would be afraid of mounting it on the little motor mount bolts ,the twisting action when droping the clutch to start the motor will be a lot of pressure against the motor mount bolts and may break them,
You got that right. It's a big concern to me. I'm looking at that.

I did replace all the studs with 5 grade, but big deal. They're still only M6. I also made the back half of the rear motor mount bracket out of stronger steel than the thin stock stuff.

The motor turned over by hand without trouble, but I know that's not the same as dumping the clutch at 5 mph.

I do know a lot of people have had trouble with their chain tensioners.
 

corgi1

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is it possible to run a strip of steel for the idler from the chain stay up to the seat stay