Which chain is resistant to any stretch

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Re: Which chain is resistant to any stretch

Postby il padrone » Mon Mar 25, 2013 11:02 pm

ironhanglider wrote:Use a 'Ghost Chainring'.

I used one as a chain tensioner with great success on a previous tandem, I have also seen some discussion of using them as a chain tensioner of 'fixies'.

If the chain does lengthen, then you can just use a bigger ring (or two).

A yes. A friend has done this to tension his tandem timing chain. I think that even by repositioning the chain-ring you should be able to slightly vary the tension.

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by BNA » Tue Mar 26, 2013 12:50 am

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Re: Which chain is resistant to any stretch

Postby ColinOldnCranky » Tue Mar 26, 2013 12:50 am

il padrone wrote:
ironhanglider wrote:Use a 'Ghost Chainring'.

I used one as a chain tensioner with great success on a previous tandem, I have also seen some discussion of using them as a chain tensioner of 'fixies'.

If the chain does lengthen, then you can just use a bigger ring (or two).

A yes. A friend has done this to tension his tandem timing chain. I think that even by repositioning the chain-ring you should be able to slightly vary the tension.



Thanks. Giraffes are set up to do just that quite easily.

In the last five day I have been amking a concerted effort into skills work in the things that work the chain a fair bit. With that I am assessing if I can do that sort of stuff without excessive loading of the chain, so maybe reducing the problem. If I can build the necessary skills to lighten greatly the forces I apply to the pedals then I may be able to live with just adjusting. I am pleased that so far my skills are improving quite a lot and the chain is still staying reasonably tight.
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Re: Which chain is resistant to any stretch

Postby il padrone » Tue Mar 26, 2013 10:51 am

Of course, long term your best solution may be to get a unicycle frame made up that includes an eccentric bottom bracket. This enables the routine adjustment of your chain to the required amount of tension.

Image




OR there is always this different option :o

Image
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Re: Which chain is resistant to any stretch

Postby find_bruce » Tue Mar 26, 2013 11:46 am

il padrone wrote:OR there is always this different option :o

Image

Yeah but then he will be complaining abour tyre wear causing slippage - or does he need a couple of eccentric hubs to go with the eccentric BB :D
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Re: Which chain is resistant to any stretch

Postby ColinOldnCranky » Tue Mar 26, 2013 5:12 pm

il padrone wrote:Of course, long term your best solution may be to get a unicycle frame made up that includes an eccentric bottom bracket. This enables the routine adjustment of your chain to the required amount of tension.

8) More than half the problem is probably due to a small but inevitable eccentricity on one or both chain wheels. Your adjustable eccentricity solution would be the bees knees.
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Re: Which chain is resistant to any stretch

Postby trailgumby » Tue Mar 26, 2013 5:24 pm

Not sure if they still make 'em, but Rohloff's 9-speed chains were legendary for outlasting the next best (XTR/Dura Ace) by 5 or six times.
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Re: Which chain is resistant to any stretch

Postby JonoMarshall » Wed Mar 27, 2013 2:10 pm

So glad someone mentioned that chains don't stretch... it's "chain wear".

Having a shorter chain (microdrive) will result in less slack but if you want a setup that will last a long period of time then go for as long a chain as possible (less wear on individual links over time).

Most chains are rarely produced (as far as I know) to be ultra-strong (and have less-wear) with the exception of BMX products. As always though your drive will only be as strong/wear resistent as your weakest part (most likely your ring/cog).
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Re: Which chain is resistant to any stretch

Postby mikesbytes » Wed Mar 27, 2013 3:58 pm

ColinOldnCranky wrote:More than half the problem is probably due to a small but inevitable eccentricity on one or both chain wheels. Your adjustable eccentricity solution would be the bees knees.


What you need is quality track rings
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Re: Which chain is resistant to any stretch

Postby theprophet » Wed Mar 27, 2013 5:31 pm

My solution is just to replace the chain often with very cheap k mart chains spend $20 on a new chain every month or 2 and it shall be good.
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Re: Which chain is resistant to any stretch

Postby il padrone » Wed Mar 27, 2013 9:05 pm

You'd pay $20 for a Kmart chain ??? :shock: :roll:

http://www.wiggle.com/kmc-z8s-silgray-chain-116l/
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Re: Which chain is resistant to any stretch

Postby ColinOldnCranky » Wed Mar 27, 2013 10:00 pm

theprophet wrote:My solution is just to replace the chain often with very cheap k mart chains spend $20 on a new chain every month or 2 and it shall be good.

You have not grasped a significant bit I suspect.

It is not just about the chain. Indeed it is not even mainly about the chain. It is also about the effect that stretching (k-mart?) chains have on the chain wheels which makes changing chains counterproductive. The cheap stretchy chain wears the chain wheels so that changing chains itself introduces a serious problem.
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Re: Which chain is resistant to any stretch

Postby il padrone » Wed Mar 27, 2013 10:06 pm

ColinOldnCranky wrote:It is not just about the chain. Indeed it is not even mainly about the chain. It is also about the effect that stretching (k-mart?) chains have on the chain wheels which makes changing chains counterproductive. The cheap stretchy chain wears the chain wheels so that changing chains itself introduces a serious problem.

If you monitor the chain wear, such that 12 full links never 'stretch' to more than 12 1/16" you should be able to change to a new chain and repeat, and never significantly wear your chain ring and sprocket. More so if you use a steel chain-ring/sprocket (eg Surly SS chain ring and track cog) and use as large a size as you are comfy with - larger ring & sprocket will wear slower.
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Re: Which chain is resistant to any stretch

Postby mikesbytes » Tue Apr 02, 2013 8:11 pm

How many K's will this unicycle be doing?
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Re: Which chain is resistant to any stretch

Postby ColinOldnCranky » Tue Apr 02, 2013 8:58 pm

mikesbytes wrote:How many K's will this unicycle be doing?

The enature of the way of using it is about two things other than distance:

First any eccentricity of the rings so that, as the rings are ratated, the chain tension will change. If I then set it so that there is good responsiveness to idling (ie rocking forward and back) then at some point in the rotation, whether or not I am idling, the tension on the chain is excessive by normal standards.

ANd second, even with perfectly setup and matched rings (imposible) I will still get quite a bit of extra tension as I idle.

The sort of riding that is done on a giraffe is mostly about idling and parades. However I have done quite a lot of real rides that range from a couple of kms to around 10km maximum. The last time I did a distance was around 6km broken into two segments. I then rode another four in the afternoon to get home.

Though I have never metered it, I reckon that I have covered anywhere between 100 and 200km but I can't be any more specific than that.
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Re: Which chain is resistant to any stretch

Postby ironhanglider » Tue Apr 02, 2013 9:29 pm

You can reduce the eccentricity of the chainrings.

As per St. Sheldon.

That should help a bit.

Since this is similar to a tandem synch chain I expect some other principles will apply too. Such as putting the rings on the inboard side of the spider if there is a choice. Having the chain closer to the tube reduces the tendency of the chain to flex the frame. Bigger rings and dual drive would help too.

Cheers,

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