chain to frame clearance.

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a.graham52

a.graham52

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Nov 22, 2013
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island of misfit toys, maine
hello all. iv got a stock china girl. no extra add ons. the upper drive chain rubs on the "a-frame" that goes to the rear wheel. both of my bikes have done this. i can see clear marks in the paint. i tried to put the on the upper chain but it keeps coming loose every time the engine is started so i assume that way is not an option. rear sprocket is teeth are dished "in". :-||
 
2door

2door

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Sep 15, 2008
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Does the chain touch the frame all the time or just hits when you're riding?
How tight is your chain? You want 1/2" to 3/4" of slack.

No, the tensioner won't work on the top chain run. That run is under stress when the engine is driving. The tensioner, if you have to use one, should be on the bottom chain run only.

Tom
 
a.graham52

a.graham52

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Nov 22, 2013
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island of misfit toys, maine
2door said:
Does the chain touch the frame all the time or just hits when you're riding?
How tight is your chain? You want 1/2" to 3/4" of slack.

No, the tensioner won't work on the top chain run. That run is under stress when the engine is driving. The tensioner, if you have to use one, should be on the bottom chain run only.

Tom
Click to expand...
i would say there was about that much slack in the chain. i have maybe an 1/8" of clearance vetween the chain and frame. i rode for about 5 minutes today and the paint it already gone off that area on a brand new bike. and its aluminum so i dont want to go too long like this.
 
2door

2door

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If the engine is mounted correctly, that is centered in the frame then the chain shouldn't be hitting the seat stay unless the rear wheel/sprocket is too far to the left.
Can you post a photo of your installation showing chain/sprocket alignment looking forward from the rear of the bike? That would help us make some suggestions.

Tom
 
xseler

xseler

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Apr 14, 2013
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How about a couple of washers on each side of the axle inside the frame? May push the frame out just enough to clear the chain........or use a slightly smaller rear sprocket......
 
2door

2door

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xseler said:
How about a couple of washers on each side of the axle inside the frame? May push the frame out just enough to clear the chain........or use a slightly smaller rear sprocket......
Click to expand...
Both good suggestions but I still would like to see a photo or two of the install.

Tom
 
maniac57

maniac57

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Oct 8, 2011
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The best way to cure this is by using a small scissor jack from an import car to carefully spread the frame for clearance.
Use wood between the jack and frame to spread the loads and avoid denting or kinking the frame tubing.
Use a bare axle or nut and bolt to hold the dropouts at the normal wheel spacing as you spread the frame. Be extra careful on aluminum, but this works very well and is easy to do.
 
maniac57

maniac57

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2door said:
Both good suggestions but I still would like to see a photo or two of the install.

Tom
Click to expand...
Tom, You have seen the frame type. They have a coke bottle stay shape that curves in toward the wheel, then back out at the axle. LOTS of aluminum and many lower end steel frames have this shape.
My Original Pig (NEXT) required this mod to stop the chain rubbing the seatstay.
Took all of 10 minutes to fix.
Took longer to get the wheel off than fixing the frame did.
 
chainmaker

chainmaker

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Jan 19, 2010
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I've never used a rag mount but can you put a couple washers behind it, I've had to do that for a drive sheave to clear tires/ chain stays?
 
2door

2door

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I've never tried a jack but I did throw this together real quick. It's just a 1/4" aluminum turn buckle that I welded on a couple of saddles to fit frame tubing. It can go on the chain or seat stay and when you turn it it spreads the frame.
I use it when I install chain tension adjusters that take up some space on the rear axles.

Tom
 

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maniac57

maniac57

Old, Fat, and still faster than you
Oct 8, 2011
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memphis Tn
I actually though about doing something like this Tom, but it was too much effort for a tool I seldom use since I already have the screw jack.
 
Denis Zen

Denis Zen

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Mar 30, 2021
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Riding up highway 101 at sunset
a.graham52 said:
hello all. iv got a stock china girl. no extra add ons. the upper drive chain rubs on the "a-frame" that goes to the rear wheel. both of my bikes have done this. i can see clear marks in the paint. i tried to put the on the upper chain but it keeps coming loose every time the engine is started so i assume that way is not an option. rear sprocket is teeth are dished "in". :-||
Click to expand...

by taking a 2x4 and placing it within the frame putting the tip of the 2x4 on the seat post and pulling out on the opposite side of the frame where the back wheel mounts you can widen the back area just a little bit not much just a little bit and that should give you the clearance that you need
 
Tom from Rubicon

Tom from Rubicon

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Apr 4, 2016
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You may want to create a new thread Denis, I used a hydraulic power pack to spread the seat and chain stays of my Sportsman Flyer frame, to get perfect chain lines. Mind you, you are resurrecting a 7 year old thread.
Carry on sir.
Tom
 
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