# Mech question: Determining chain length...



## rzozaya1969 (Nov 28, 2004)

How can I determine the correct chain length for a bike?  I think that you put a certain front ring/back ring combination and the rear der. patita has to be completely vertical, right?

Any takers?

Thanks


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## Captain Jack Sparrow (Jan 26, 2006)

Robert :

Si es para tu hardatil Santa Cruz... la medida de largo de cadena es muy sencillo.

Solo debes colocar la cadena sobre el cassette y en la estrella mas grande (1) y en el plato mas grande (3) sin pasarla por el desviador... esto debe de ser directo de casette a multiplicación y trata de unir la cadena... exactamente donde se junten ambos eslabones de cada extremo y corta... esa es lamedida correcta para tu transmisión...

Si es una doble... sumale 2 eslabones mas y listo... Yo lo apliqué a mi HT Vertex y a mi FS ETSX y quedo muy bien :thumbsup: 

Espero haber ayudado!


Saludos!  

Sir Ranazzotti:rockon:


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## ritopc (Jul 3, 2004)

ROCKY_RENE said:


> Robert :
> 
> Si es para tu hardatil Santa Cruz... la medida de largo de cadena es muy sencillo.
> 
> ...


I'm almost sure it also important to get the right derailleur cage size. This depends, AFAIK, of the cog set-rings combination. Dunno exactly the theory behind, but I remember it is important for a proper shifting and a correct chain length.

Can anyone elaborate on this one?


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## tlg (May 21, 2004)

http://www.parktool.com/repair/printhowto.asp?id=26
Scroll down to the "Largest Cog and Largest Chainring Method."
The easiest most fool proof method.


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## Warp (May 24, 2004)

ritopc said:


> I'm almost sure it also important to get the right derailleur cage size. This depends, AFAIK, of the cog set-rings combination. Dunno exactly the theory behind, but I remember it is important for a proper shifting and a correct chain length.
> 
> Can anyone elaborate on this one?


Kind of... unless you're using special custom gear ratios like many roadies or DH'ers do, the rule of thumb is:

Three chainrings: Long cage
Two chainrings: medium cage
One chainring: short cage.

The reason?
On a single chainring set-up, the RD has to take the slack produced by the cog's difference only.
Add a chainring, and you have to take the slack of 10-12 teeth more. Add two chainrings and you'll have to take the slack of 20-24 teeth.

This is independent from chain lenght.


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## tigerdog (Mar 16, 2004)

tlg said:


> http://www.parktool.com/repair/printhowto.asp?id=26
> Scroll down to the "Largest Cog and Largest Chainring Method."
> The easiest most fool proof method.


That's the one I use.


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## rzozaya1969 (Nov 28, 2004)

Thanks for the advice, I like that, I'll see how it goes... I'll update soon... hopefully


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