Final Chain Tensioner

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rex.webb
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Re: Final Chain Tensioner

Post by rex.webb »

OK
Surely the tension in the chain changes as the wheel goes up and down because the swingarm pivots round a point on the frame that is further back the point, ie the gearbox sprocket, that the chain pivots round. I am happy to be corrected but that's the way my brain cell understands it.
YES if there is a Large distance from .
Gearbox Shaft to Swinging Arm pivot ?
Never had any trouble with my H/Weights traveling across europ and scandinavia?
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Mick D
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Re: Final Chain Tensioner

Post by Mick D »

Hi

I've just done a quick measure and calculation, assuming the geometry is ideal, over two inches of suspension travel the difference in effective lever length is 0.004" - so double that for the effect on the chain = about 0.008" - hardly a reason to seek a cure.

Harry 44 is spot on with his assumption regarding a derailleur type tensioner, as soon as engine braking is used the chain will slacken on it's top run and probably jam between the gearbox sprocket and crank case.

Regards Mick
SPRIDDLER
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Re: Final Chain Tensioner

Post by SPRIDDLER »

Some of the motorbike tensioners are a type of sprung loaded Derailleur design but others are more of a mid-chain fixed sprocket which exerts pressure on the chain run. With either type it appears that if the chain direction reversed or the spring failed it probably wouldn't cause a disaster.
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Rob Harknett
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Re: Final Chain Tensioner

Post by Rob Harknett »

SPRIDDLER wrote:Some of the motorbike tensioners are a type of sprung loaded Derailleur design but others are more of a mid-chain fixed sprocket which exerts pressure on the chain run. With either type it appears that if the chain direction reversed or the spring failed it probably wouldn't cause a disaster.
Surely creating a weak point, compared it to the sturdy gearbox and rear wheel sprockets. Looks too fragile to stay in line with gearbox and rear wheel sprockets, More maintenance, more parts to fail, more wear on the chain.
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Re: Final Chain Tensioner

Post by SPRIDDLER »

Rob Harknett wrote: Surely creating a weak point, compared it to the sturdy gearbox and rear wheel sprockets. Looks too fragile to stay in line with gearbox and rear wheel sprockets, More maintenance, more parts to fail, more wear on the chain.
I can see no great benefit from fitting one on a road or touring bike except that it would take up some chain wear and fewer manual chain adjustments would be required, (until the drive and rear sprockets became hooked and knackered).

It would have a shock-absorbing effect since the sprung tensioner creates a 'bow' in the chain. As greater or lesser pull forces try to straighten out the 'bow' the sprung tensioner would absorb or soften some of the the snatch.
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Re: Final Chain Tensioner

Post by G15 Roy »

SPRIDDLER wrote:
Rob Harknett wrote: Surely creating a weak point, compared it to the sturdy gearbox and rear wheel sprockets. Looks too fragile to stay in line with gearbox and rear wheel sprockets, More maintenance, more parts to fail, more wear on the chain.
I can see no great benefit from fitting one on a road or touring bike except that it would take up some chain wear and fewer manual chain adjustments would be required, (until the drive and rear sprockets became hooked and knackered).

It would have a shock-absorbing effect since the sprung tensioner creates a 'bow' in the chain. As greater or lesser pull forces try to straighten out the 'bow' the sprung tensioner would absorb or soften some of the the snatch.

Good thinking Neville at no time had the snatch point been mentioned.
Roy
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Harry44
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Re: Final Chain Tensioner

Post by Harry44 »

si is does non opportunus vos postulo a maior pango
56G80S
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Re: Final Chain Tensioner

Post by 56G80S »

Sure I remember a primary chain tensioner on the Triumph TR6P that I had, really a form of the slider that Harry44 posted. Or perhaps it was on another of the machines I had.

It would be better to fit a rear enclosed chaincase - that would extend chain life although often ugly.

Johnny B
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Peter Morris
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Re: Final Chain Tensioner

Post by Peter Morris »

leswaller wrote: 'has anyone tried it on our bikes"
My G3C has one of the modern pad type tensioners (not my doing, bought it like it). Worked fine so now I'm rebuilding bike I've decided to keep it.... Bike isn't standard anyway, a tensioner isn't going to make a difference.
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ajscomboman
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Re: Final Chain Tensioner

Post by ajscomboman »

I should think that with a rear sprocket that size it would require a tensioner to allow the bottom run of the chain to clear the frame. Most road models it is a pointless fitting in my humble opinion.
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