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 Post subject: Measuring chain length
PostPosted: Sun Mar 31, 2019 1:02 am 
Gold Trader
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I've done this hundreds of times and never struggled but today I built a 1x9 for my son (pics will be added to a build thread), and I'm having issues.

Measured the chain using big ring to big ring, added 2 links then fitted.

When shifting up to the high ratios, the mech cage hits the cogs. I've adjusted the tension screw as far as it goes but it is still too close and the cage is at a big angle.

Is the chain too short? Is my measuring technique no longer correct?


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Last edited by ishaw on Sun Mar 31, 2019 11:50 am, edited 1 time in total.
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PostPosted: Sun Mar 31, 2019 3:42 am 
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mech spring in the wrong hole?


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 Post subject: Re:
PostPosted: Sun Mar 31, 2019 9:46 am 
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Only has one as far as I'm aware.


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PostPosted: Sun Mar 31, 2019 10:14 am 
retrobike rider
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ishaw wrote:
I've done this hundreds of times and never struggled but today I built a 1x9 for my son (pics will be added to a build thread), and I'm having issues.

Measured the chain using big ring to big ring, added 2 links then fitted.



Is the chain too short? Is my measuring technique no longer correct?


I used to do this, but now I go small to small with chain running through the jockeys as normal and then cut chain with no contact between mech and cassette.

I tried it the other day when on a job with a colleague who measures big to big and we came out the same but I find it easier to get it right.

Also, going small to small if you make a mistake your chain ends up a link too long which is easier to correct.

When shifting up to the high ratios, the mech cage hits the cogs. I've adjusted the tension screw as far as it goes but it is still too close and the cage is at a big angle.

Do you mean high or low gears?

If you mean the top jockey wheel is hitting the cassette in a low gear that sounds like the mech is incompatible with the cassette size.

Pics would be good.


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 Post subject: Re:
PostPosted: Sun Mar 31, 2019 10:25 am 
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Thanks for the alternative approach. Not quite sure I follow your technique, could just be me suffering sleep deprivation. Curse daylight saving.


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 Post subject: Re:
PostPosted: Sun Mar 31, 2019 11:51 am 
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Pics up


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 Post subject: Re:
PostPosted: Sun Mar 31, 2019 1:35 pm 
retrobike rider
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I would say the problem lies with the capacity of the derailleur, rather than the chain length.

Have you tried/could you try a cassette with smaller first gear?


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 Post subject: Re:
PostPosted: Sun Mar 31, 2019 2:45 pm 
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I'm sure I have a smaller cassette, though it's not a huge one on there. Fairly standard I'd say 34t max. Front is 34 too.


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 Post subject: Re:
PostPosted: Sun Mar 31, 2019 6:42 pm 
retrobike rider
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Agree 34T is not huge. Do you know the maximum capacity of the mech?

Just looked at the picture again. What happens if you let the b screw back out?


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 Post subject: Re:
PostPosted: Sun Mar 31, 2019 7:52 pm 
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I'll check the max capacity later. If the b screw is backed out, it xtr fet on to the top cog (when I started I couldn't get to the top 3 so it's an improvement.


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