Chain tensioners

[-Savage-]

Ok, so we all know that chain tensioners work in bikes at high revs, for the cam chain, and this means that the chain does not need to be adjusted periodically, as the tensioner takes up the slack and solves that problem.

So..... why can we not use some sort of tensioner for the drive chain to the rear wheel?

Something like the tensioner you find on a bicycle, a cog on a sprung arm, which takes up the slack on the drive chain.

Surely this has been thought about before, but not adopted as a viable method. So why not?

https://www.diaryofamountainbiker.co.uk/oct05/singlespeed_chainset.jpg
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[Raffles]

Such things are commonplace on trials bikes where there is constant volatile movement of the swinging arm. I'm sure that the clever people who design road bikes will have addressed the issue and deemed it impractical or uneconomic to install such automatic tensioners.
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A good loser will always be a loser.

[yen_powell]

I seem to remember I had an old Honda XL185 that had just such a tensioner.
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[Jim Mc]

Chain isn't threaded correctly through that rear derailleur. Should be over the top pulley, under the bottom.

But then why there's a derailleur on a fixie in the first place is a mystery.

[Nixon]

Without sounding too much like a heathenistical Ludite, what is wrong with the system we have at the min? I mean a couple of seconds with a spanner and you have a chain as perfectly tensioned as you need it.

On a more technical note, friction reduces power, loss of power at the chain makes all the engineers hard work on making power at the engine pointless, its the same reason most factories don't put O or X ring chains on 125s because they sap power.

[ms51ves3]

[Slacker24seve...]

[Fisty]

https://www.renold.com/Products/TransmissionChainSprockets/Roll-Ring.asp

We use these at work, quite clever bits of kit.
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[pinkyfloyd]

[ms51ves3]

[Fisty]

[Jim Mc]

[Slacker24seve...]

[Jim Mc]

https://upload.wikimedia.org/wikipedia/commons/thumb/4/42/Rear_dropout.JPG/220px-Rear_dropout.JPG

It is the traditional type, you wouldn't need more than 10mm on a bike chain, the picture you demonstrated is no doubt better, but it's a cosmopolitan design.[/img]

[MarJay]

https://cdn.bikechatforums.com/files/dsc01406.jpg
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Remember kids, bikes aren't like lego. You can't easily take a part from one bike and then fit it to another.

[McJamweasel]

[Fisty]