chain tension

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#1
is it possible to ride with loose chain like this?
WP_20190105c.jpg

with tension according to instructions <1" if chain starts to comes off it can damage the transmission and engine; with this length it can come off without doing any damage but it is too loose. will it jump under load? the solution of course is spring tensioner, but i still dont have it.
 


FurryOnTheInside

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#2
No it is not safe to ride with the chain so slack. The chain can damage or break spokes. The chain can snap and hit your leg. Etc etc etc.
You can probably shorten the chain a full link, or shorten and add a half link. (try ebay)
 
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#3
perhaps i did not make the problem clear enough. with chain in normal tension if you displace the tensioner roller just 1 mm off one side or another chain would not sit on the sprocket's teeth, it starts to come off (it can happen for no reason). it cannot come off easily because the length does not allow it; so it becomes stuck in extreme tension and starts pulling on transmission and engine's mounting plate (in my case there are 5mm rubber pads between it and frame, so it can move a little). if this happens at high speed and i would not recognise that chain is stuck in high tension and continue holding the throttle, the running engine would pull off transmission, engine or the tensioner or break the frame. (this hub is with freewheel, so at least wheel would not get stuck). with chain this loose there is enough length in it to come off without pulling engine and tensioner; although since on the bottom of sproket it does not sit on teeth it may jump over teeth under load; but at least it is safe for the bike and engine.
 
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CrazyDan

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#4
Try scooting the tensioner back a little more and make sure it is lined up perfectly. Does your sprocket have any side to side wobble? If so try to get it as true as possible to prevent the chain from jumping off.
 

FurryOnTheInside

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#5
Having the chain loose in order to allow some slack even when the chain is running across the tops of the teeth is solving the wrong problem. The chain should never run across the tops of the teeth.

Remove the rubber from under all mounts. Engine mounts and tensioner mount.

If the tensioner is wobbly even without rubber then make your own tensioner that is attached to both the chain stay and the seat stay.
 
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#6
i discovered that if chain comes off towards spokes it blocks wheel even despite freewheel. it is a terrible system, i dont know who designed it. on a motocycle is it the same? getting chain stuck in high tension and rotating transmission with just two fingers, the leverage it creates is huge, everything is cracking; if it happens at speed i think it'll break frame and tear engine apart.
Try scooting the tensioner back a little more and make sure it is lined up perfectly. Does your sprocket have any side to side wobble? If so try to get it as true as possible to prevent the chain from jumping off.
it has no side wobble; adjustment is only approximate; it can get in high tension for no reason, a small piece of wood, grass, dirt, whatever is enough for it to go 1 mm aside and in tension.
in engineering systems should be designed to completely exclude such events; this is like playing with explosive.
 
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#7
Having the chain loose in order to allow some slack even when the chain is running across the tops of the teeth is solving the wrong problem. The chain should never run across the tops of the teeth.
once in a while this inevitably will happen; maybe every ride. that's the problem that spring tensioner should solve. so chain would come off without damaging bike and the rider should notice it and hit on breaks before it blocks the wheel; although if it comes to spokes it would block wheel instantly and there would be accident.
 

Spare_Parts

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#8
We already went through this in the other thread. Take a link out, remove the rubber under the tensioner and readjust the chain. Thousands of people have done this without issue.

Or sell the bike.
 

FurryOnTheInside

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#9
once in a while this inevitably will happen
I disagree. You are trying to make the chain come off more safely but the chain needn't ever come off. Redesign your chain management until it will not happen; it can easily be achieved.
The chain must stay on the sprocket. There is no safe derailment.
Check out other people's builds. I have a few photos of mine too of you care to see, click on my profile. :)
 
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#10
in general in industry there is no protection against that event when chain goes in high tension, so it will lead to damage of equipment (tearig engine, axle apart)?
on a motocycle chain is adjusted the same way as on a single speed bike, so right alignment is fixed firmly; but if something gets stuck into chain and makes it in high tension it will break engine and other parts?
 
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