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PostPosted: Sat Sep 22, 2018 10:58 pm 
Retro Guru

Joined: Sun Jun 16, 2013 2:57 pm
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Location: Porto / Plymouth
I need to replace a chainset on bike with a 3x9 speed Deore drivetrain, and I'm tempted to save money by getting an 8 speed Shimano chainset. Some say the rings on an 8 speed chainset will be too wide for a 9 speed chain, resulting in horrendous chainsuck. Others claim Shimano 8 speed and 9 speed have been using the same width rings for more than a decade now.

Anyone know the truth of all this?


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 Post subject: Re:
PostPosted: Sat Sep 22, 2018 11:27 pm 
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Joined: Thu Jun 23, 2011 11:25 pm
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Location: It's not easy being a dolphin.
Does not pose a problem. I'm speaking from experience, in a very very short time it will bed in fine; even beefy old school Blackspire DH single rings work fine with 9 speed. Initially a good dose of oil on the chain isn'nt a bad thing to do.

Technically, the rear sprocket width between 8 and 9 speed is as near as damnit the same; only 0.02mm if I recall correctly. Front chain rings vary between manufactures much more than that, and Shimano are always (too) thin in my mind to have any chance of longevity.


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PostPosted: Sat Sep 22, 2018 11:48 pm 
Retro Guru

Joined: Sun Jun 16, 2013 2:57 pm
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Location: Porto / Plymouth
That's correct, the cassette sprockets of 9 speed are 1.78 mm wide and those of 8 speed are 1.80 mm wide. 8 speed chains are 7 mm measured across the rivet, but 9 speed chains are 6.5 to 7 mm. My LBS swears it's really a bad idea to run 8 speed chainrings with a 9 speed cassette and chain, but I remain unconvinced.


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 Post subject: Re:
PostPosted: Sun Sep 23, 2018 1:19 am 
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Location: It's not easy being a dolphin.
I would go as far as marginally sub-optimum with a barely perceptible if not unnoticeable difference. :-)

I mean, front shifting is done brutally - turning sausages over in a frying pan with tongues requires more technique and subtlety.

There is no way it requires the tolerance level that Shimano would like you to believe.


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PostPosted: Sun Sep 23, 2018 5:22 pm 
King of the Skip Monkeys
King of the Skip Monkeys

Joined: Wed Nov 07, 2007 4:34 pm
Posts: 29465
I'm running a 10spd chain/ cassette on a chainset designed for 7spds

So there.


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PostPosted: Sun Sep 23, 2018 5:26 pm 
Retro Guru

Joined: Fri May 15, 2015 4:57 pm
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legrandefromage wrote:
I'm running a 10spd chain/ cassette on a chainset designed for 7spds

So there.



But ... does it function flawlessly ?


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PostPosted: Sun Sep 23, 2018 5:31 pm 
King of the Skip Monkeys
King of the Skip Monkeys

Joined: Wed Nov 07, 2007 4:34 pm
Posts: 29465
even better than that, oil from a maids thigh helps


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 Post subject: Re:
PostPosted: Sun Sep 23, 2018 7:20 pm 
Old School Hero

Joined: Sat Apr 15, 2017 12:26 pm
Posts: 205
Flipping heck! That's some, er, 'unusual' maids you must have in your neck of the woods.


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PostPosted: Sun Sep 23, 2018 7:52 pm 
GOLD | PoTM | Rider | rBOTM
GOLD | PoTM | Rider | rBOTM
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Joined: Tue Feb 26, 2013 6:26 pm
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Location: 54 Festive Road Winchcombe GLOUCS Yarp...
It’s fish oil. They’re mermaids.


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PostPosted: Sun Sep 23, 2018 8:07 pm 
Retro Guru

Joined: Sun Jun 16, 2013 2:57 pm
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Location: Porto / Plymouth
I believe there may be other fishy smelling lubricants that ordinary maids can provide.


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