SORA rear derailleur problems

[JonnyBlade]

I have just built up a bike with a nice little carbon frame and SORA chain, gear and brake set. Everything went as planned until I came round to setting the gears up. When I'm in the lower front cog and higher back gears, the chain almost doubles up on itself.

Any ideas will be gratefully accepted and tested to the full

 

[Angelfishsolo]

By highest do you mean the largest rear cog or the smallest?
When you say it doubles up do you mean it folds over on itself (chain suck)?

I have just built up a bike with a nice little carbon frame and SORA chain, gear and brake set. Everything went as planned until I came round to setting the gears up. When I'm in the lower front cog and higher back gears, the chain almost doubles up on itself.

Any ideas will be gratefully accepted and tested to the full

 

[gbb]

Have you got the chain length correct ?
Easiest way i find is to pass the chain over the large chainwheel and the biggest cog on the cassette...do not pass it through the derailleurs....and add one full link. Works for me every time.

 

[JonnyBlade]

By highest do you mean the largest rear cog or the smallest?
When you say it doubles up do you mean it folds over on itself (chain suck)?

Yes Buddy, Small cog on the front and smallest cog on the back and yes it seems to fold back on itself. Very odd!!!

 

[Angelfishsolo]

Ok. By running the chain from smallest front to smallest rear you are crossing the chainline. As a rule of thumb when in the smallest front cog only use the largest three rear cogs and when in the largest front cog only use the smallest 3 or 4 rear cogs. The middle front can be used across the whole range of rear cogs.

You are experiencing chain suck by the sound of it because of the crossed chainline. If you use the front and rear mechs in harmony you should be ok.

 

[the_mikey]

Does sound like 'chain suck' to me too, although even with a crossed chainline I don't get chainsuck.

The only time I've had chainsuck with a 9 speed shimano chainset/cassette was when I lubed the chain with finishline wet. I cleaned the chain and tried some ptfe spray and it was fine after, even lubed using finish line wet again and it was all ok.. Very strange.

 

[mickle]

Chain suck is when the (usually middle) chain ring wont let go of the chain - and drags it up between the chainset and chainstay. It's enough to wreck some frames.

It's definitely not chain suck that's being discussed.

 

[PatrickPending]

as has been said before chain length sounds the most likely suspect, don't forget to set the b-screw too - this probably needs setting up correctly.

seee these pages

http://www.parktool....ents-derailleur

and sheldon talks about chain length too

http://www.sheldonbr...adjustment.html

 

[Angelfishsolo]

I stand corrected

Chain suck is when the (usually middle) chain ring wont let go of the chain - and drags it up between the chainset and chainstay. It's enough to wreck some frames.

It's definitely not chain suck that's being discussed.

 

[JonnyBlade]

Thanks for all the help guys

All sorted now, a few adjustments here and there and a quick chain link removal seems to have me up and running now