Another Chain Tensioner Idea

[Pilotgeek]

Well, I used to run without a chain tensioner for quite a long time. I got really lucky at first... my pedal chain and motor chain both had almost the exact same amount of slack, so I just ran it without a tensioner. I started with about 1" of slack, and this worked great for about 2000 miles, until things started to wear out. At its worst, I had about 1.25"-1.5" of slack. It has NEVER fallen off (perfect alignment) but I figured I shouldn't push my luck.

Moving the engine forward wasn't really an option; my frame is pretty small and I don't have much room to shift the engine. Besides, it would change the angle a bit and the mounts didn't fit flush that way. I didn't really care to throw down $30-$40 for a premade high quality solution if I didn't absolutely have to, and I do not trust the stock tensioner one bit, so I decided to hack this together out of the original kit tensioner.

It clamps to the seat tube, below the engine mount. It's just both sides of the tensioner cut to the bare minimum, with a longer bolt replacing the original to put a roller on it. The distance outward can be adjusted by washers on the axle, and the tension and alignment can be changed by loosening the bolts and sliding it up the seat tube. Due to being so close to the engine mount, I can only slide it up a little bit, but it gave me about .75" more adjustment. I could probably get more out of a bigger roller, but right now I have that "perfect" .5"-.75" .

I'm still not huge on the whole tensioner idea, but this will do for now. How long do these plastic rollers usually last when aligned well?

 

[diceman2004]

Really ? 1-1/2 inches and it didn.t end up on top of the teeth ?
That could have done some nasty damage if it did .

Anyways ... awsome idea ... I like that a lot ... might do that myself if you don,t mind .
Its clean .. small .. and out of the way .

I,m cutting out my bottom chainstays and replacing them with some tubes I cut from a handle bar i had ( doing this so i can run the chain tensionerless )
It is nice to have something there to fine tune the slack .

 

[Pilotgeek]

I never mind if people use my ideas, that's why I post them when I can. I've received so many good ideas from this forum, it's only fair I give some back. Yes, fine tuning is very nice, especially considering I may get a new chain soon, which will require frequent adjustment while breaking in.

And yeah, I'm as surprised as you are at the slack. I even tried purposely rolling the chain off, but I could not walk it off on purpose. I think using a sprocket adapter may have helped it stay on (no wobble). It was close though, and if it jammed on top of a tooth without rolling over the side, something would break. Nothing beats the old 78 Suzuki RM80 I had though. We got it for $100 at a swap meet, and we just put oil and gas in it and ran it til it died. Had probably 2" of slack and would rub on the chainstay guard, but it never fell off.

I go off on tangents too easily.

 

[mechaniczman]

I would try this if the bolt on my chain tensioner wasnt stripped to were I cant get it off...

 

[Pilotgeek]

Drill or grind it off.