| | | Mounting Techniques Every frame is different. Share and ask questions about mounting your motorized bicycle engine kit to your bicycle frame or bicycle rack | adjustable chain tensioner idea Discussion at Motorized Bicycle Engine Kit Forum in the Mounting Techniques forum. Has anyone designed an adjustable chain tensioner? By adjustable, I mean something that has a threaded area that you could ...  | 
06-19-2009, 07:24 PM
| | Motorized Bicycle Elite Member | | Join Date: May 2008
Posts: 117
| | adjustable chain tensioner idea Has anyone designed an adjustable chain tensioner? By adjustable, I mean something that has a threaded area that you could make fine adjustments to get it "just right". My stock wheel slowly walks lower and lower until I have to move it back up and re-tighten. I can't make it too tight because it stops the tensioner wheel from moving freely.
I bought a turn buckle from Home Depot and was going to weld a bracket on it to hold the tensioner wheel and secure both ends, that way I could just adust the tension by rotating the turn buckle a couple of turns to raise or lower the tensioner wheel.
Has anyone been down this road? Any techniques work in the past?  | 
06-19-2009, 09:13 PM
|  | Moderator | | Join Date: Sep 2008 Location: Littleton, Colorado
Posts: 1,903
| | Re: adjustable chain tensioner idea Hey, Cap,
If I'm understanding you correctly it sounds as if a spacer between the tensioner wheel bearing and the bracket might solve your problem. What I assume is happening is that when you tighten the wheel it is putting pressure on the bearing outer race, (or bushing if so equipped) and binding it up. A washer or something to act as a spacer at the point where there is no contact with the wheel or outer bearing area should allow you to tighten the wheel sufficiently to keep it from loosening. All this, if, I'm understanding your problem right.
Tom
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Last edited by 2door : 06-19-2009 at 09:18 PM.
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06-19-2009, 09:35 PM
| | Motorized Bicycle Elite Member | | Join Date: May 2008
Posts: 117
| | Re: adjustable chain tensioner idea 2Door,
Yea, that's the problem. The bolt that the tensioner wheel rides on has a shoulder on it to prevent it from getting too close to the bracket when you crank down the nut. Unfortunately, my shoulder or cuff is worn down and the bolt acts like a clamp and it stops the wheel from turning. If I don't make it tight enough the wheel slides down and the chain gets loose. That's why I'm trying to re-invent the"mousetrap" tensioner.
The spring tensioner I got from TSC bounces around too much to be effective. | 
06-20-2009, 05:37 PM
|  | Moderator | | Join Date: Sep 2008 Location: Littleton, Colorado
Posts: 1,903
| | Re: adjustable chain tensioner idea Cap,
Have you tried the skate board wheel modification? Many of us abandon the kit supplied tensioner pully for a good quality skate board wheel. You need to do some work to the wheel but cutting a groove in it to fit the chain. I used a lathe to spin the wheel but others have had luck with a drill press or hand drill and another tool like a Dremel to cut the groove. There is a link to some examples of skate board wheels. I'll try to find it and post it for you. Most of them I've found have a 5/16" bearing bore and good bearings inside and out. A trip to Ace Hardware should provide you with the proper length/diameter bolt. Hope this helps.
Tom
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06-20-2009, 05:42 PM
|  | Moderator | | Join Date: Sep 2008 Location: Littleton, Colorado
Posts: 1,903
| | Re: adjustable chain tensioner idea Cap,
Here's that link I was looking for. Skate wheel tensioner mod
Tom
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06-20-2009, 10:11 PM
|  | Motorized Bicycle Elite Member | | Join Date: Mar 2008 Location: Treasure Coast, Florida
Posts: 747
| | Re: adjustable chain tensioner idea Here is my solution.......... Spring Return Chain Tensioner
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06-20-2009, 10:46 PM
|  | Motorized Bicycle Elite Member | | Join Date: Mar 2009 Location: upstate NY
Posts: 1,452
| | Re: adjustable chain tensioner idea my tensioner wheel stays right where i put it because i tightened it good.
but my wheel does not turn with the chain,and on mine its not the tightness of the nut its the chain angle on my wheel. the chain just kinda runs across the plastic wheel without the wheel turning. the plastic wheel turns if i turn it by hand.
so i am still working on a replacement. | 
06-30-2009, 08:37 PM
|  | Motorized Bicycle Elite Member | | Join Date: Mar 2009 Location: Wallyworld Conn.
Posts: 108
| | Re: adjustable chain tensioner idea Rick at boygofast has a new BB tensioner,It was included with my new engine but im sure hed sell you one,it works great....much less cheesey than I am used to seeing!!
Good luck
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