Please help me fix my commencal gears

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m_cozzy
Posts: 117
Joined: Sat Sep 19, 2009 16:11 pm

Please help me fix my commencal gears

Postby m_cozzy » Fri Mar 21, 2014 11:15 am

I have had this bike from new from a large internet bike company for about 5 months now & barely used it as the gears are so bad. I had never been able to adjust them so they shift up and down smoothly without jumping & skipping. I could get them to work changing up, but that would stuff them for changing down & vice versa.
The other day I discovered that the b screw, I think its called, had been wound right in to possibly take all the slack out of the chain. Adjusting this to give a 6mm gap I read about made them much better, but it now seems the chain is too long?
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This is what it looks like now on the smallest gears, with the derailer wrapping round itself & the chain hanging slack.
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This is what it looks like on the largest 2 gears, looks like I could take quite a few links out?
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Never had sram stuff before and not too impressed as my shimano equipped bikes are all faultless, but perhaps I have been unfairly blaming them if I have a Friday afternoon special & some fool fitted the wrong chain to my bike in the factory?
Banned from singletrack forum again :-)

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Pesky Jones
Posts: 2937
Joined: Wed Aug 22, 2012 09:43 am

Re: Please help me fix my commencal gears

Postby Pesky Jones » Fri Mar 21, 2014 11:55 am

First of all get your chain size right - Largest casette sprocket to largest chainring sprocket + 2 links.

You do this without running the chain through either mechs. If you have a chain device DO run the chain through that however.

Then watch this video https://www.youtube.com/watch?v=UH43OCmArUw

Watch it carefully, and follow each step.

Chunkers1980
Posts: 7909
Joined: Tue Feb 10, 2009 14:12 pm

Re: Please help me fix my commencal gears

Postby Chunkers1980 » Fri Mar 21, 2014 12:09 pm

It looks about right.

Not sure of the arc on that frame, but with some sag there might be no slack. I'd run less b tension gap than that.

Check your cables are clean and routed properly.

Cqc
Posts: 900
Joined: Tue Nov 19, 2013 18:46 pm

Re: Please help me fix my commencal gears

Postby Cqc » Fri Mar 21, 2014 17:14 pm

Youve had a bike with bad gears for 5 months and not sorted it out?! About time! If it's a 3x system (I can't see) then that medium cage mech won't be able to cope with large large or small small ring combinations, so your going to have to compromise with a short chain - cant do large large, or a long chain- cant do small small

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Pesky Jones
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Joined: Wed Aug 22, 2012 09:43 am

Re: Please help me fix my commencal gears

Postby Pesky Jones » Fri Mar 21, 2014 17:23 pm

Chunkers1980 wrote:It looks about right.

Not sure of the arc on that frame, but with some sag there might be no slack. I'd run less b tension gap than that.

Check your cables are clean and routed properly.


Not sure there is one, tit pivots at the BB so the length doesnt differ??

m_cozzy
Posts: 117
Joined: Sat Sep 19, 2009 16:11 pm

Re: Please help me fix my commencal gears

Postby m_cozzy » Fri Mar 21, 2014 17:32 pm

Good call regarding sag, I hadn't considered that. Its an x2 at the front.
Banned from singletrack forum again :-)

coulddobetter
Posts: 765
Joined: Sat Jun 15, 2013 01:25 am

Re: Please help me fix my commencal gears

Postby coulddobetter » Fri Mar 21, 2014 18:38 pm

http://m.pinkbike.com/news/tech-tuesday ... -2010.html

I found this by far the clearest guide , I run similar set up to you on a hardtail.

m_cozzy
Posts: 117
Joined: Sat Sep 19, 2009 16:11 pm

Re: Please help me fix my commencal gears

Postby m_cozzy » Sun Apr 06, 2014 12:59 pm

Just an update to the thread, following the guides the chain was too long, I took 2 links out, could have done 3 but played it safe. Shifting is now great :-)
Lesson learnt, just because its new doesn't mean its been build correctly.
Banned from singletrack forum again :-)


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