7sp chainsets, 9sp chain

[news.virgin.net]

Hi,
I just put a new 9sp shimano cassette & chain on and still have and old
SuntourSR chainset that I ripped of a halfords bike cos I did'nt have
anything else and I needed to get back in action. Anyway - I now have
terminal chainsuck on the granny ring and it jumps on the middle ring. The
chain I took off was terribly worn and I think it ate the chain rings quite
badly. The question is - is the chainsuck due to the fact that I'm using an
7sp chainset with a 9sp chain or because the chainset is well worn ?

Also, can I get away with a Deore front mech (44-48 teeth spec) with a 52
tooth front chain ring ?

Cheers,

Bruce.

 

[Paul Boyd]

news.virgin.net said the following on 05/02/2008 17:34:
> Hi,
> I just put a new 9sp shimano cassette & chain on and still have and old
> SuntourSR chainset that I ripped of a halfords bike cos I did'nt have
> anything else and I needed to get back in action. Anyway - I now have
> terminal chainsuck on the granny ring and it jumps on the middle ring. The
> chain I took off was terribly worn and I think it ate the chain rings quite
> badly. The question is - is the chainsuck due to the fact that I'm using an
> 7sp chainset with a 9sp chain or because the chainset is well worn ?

Entirely possible. A 9-speed chain is quite narrow, and a 7-speed
chainring is quite thick. Chain suck is caused when the chain, for
whatever reason, doesn't release from the bottom of the chainring. In
this case, the reason is that the chain is too tight on the teeth. This
is the width of the teeth, not the fact that they've worn.

> Also, can I get away with a Deore front mech (44-48 teeth spec) with a 52
> tooth front chain ring ?

Try it and see! In theory it shouldn't work very well, but a front mech
is a pretty crude device. Just make sure it clears the big ring easily
over the whole length of the cage.

--
Paul Boyd
http://www.paul-boyd.co.uk/

 

[Pete Biggs]

Paul Boyd wrote:

> Entirely possible. A 9-speed chain is quite narrow, and a 7-speed
> chainring is quite thick.

7 and 9 speed chains have the same *internal* width and are compatible with
the same chainrings.

~PB

 

[news.virgin.net]

"Pete Biggs" <[email protected]> wrote in
message news:[email protected]...
> Paul Boyd wrote:
>
> > Entirely possible. A 9-speed chain is quite narrow, and a 7-speed
> > chainring is quite thick.
>
> 7 and 9 speed chains have the same *internal* width and are compatible
with
> the same chainrings.
>
> ~PB
>
>

So the chain suck is due to worn chain rings ? They seem to be made of
aluminium and I would have thought a worn chain could have eaten them really
quickly, though I rarely use the small ring.

 

[DavidR]

"news.virgin.net" <[email protected]> wrote

> I just put a new 9sp shimano cassette & chain on and still have and
> old
> SuntourSR chainset that I ripped of a halfords bike cos I did'nt have
> anything else and I needed to get back in action. Anyway - I now have
> terminal chainsuck on the granny ring and it jumps on the middle ring.
> The
> chain I took off was terribly worn and I think it ate the chain rings
> quite
> badly. The question is - is the chainsuck due to the fact that I'm using
> an
> 7sp chainset with a 9sp chain or because the chainset is well worn ?

I use 9sp chains throughout now. On a 7sp the reduced width has stopped it
getting jammed between ring and frame. I think lighter weight has
fundamentally reduced whip anyway and made shifting better.

 

[Paul Boyd]

Pete Biggs said the following on 05/02/2008 18:35:

> 7 and 9 speed chains have the same *internal* width and are compatible with
> the same chainrings.

Oh well, that buggers that theory then!

--
Paul Boyd
http://www.paul-boyd.co.uk/

 

[Rob Morley]

In article <[email protected]>, news.virgin.net
[email protected] says...
> Hi,
> I just put a new 9sp shimano cassette & chain on and still have and old
> SuntourSR chainset that I ripped of a halfords bike cos I did'nt have
> anything else and I needed to get back in action. Anyway - I now have
> terminal chainsuck on the granny ring and it jumps on the middle ring. The
> chain I took off was terribly worn and I think it ate the chain rings quite
> badly. The question is - is the chainsuck due to the fact that I'm using an
> 7sp chainset with a 9sp chain or because the chainset is well worn ?
>
More likely the old chain has raised a burr on the edge of the worn
teeth - try running a fine file around the rings. You could also
investigate the possibility of refitting them backwards.