[duclicsic]

Hi there,

I recently put a whole new bike together and for the first time went all SRAM for my drivetrain needs. I went with an X9 shifter and short cage rear mech, and for the most part they've worked a treat. However one small problem that is starting to bug me, and that's when I'm shifting up to a higher gear sometimes the satisfying clunk of it changing over doesn't come, and instead it feels like I get a sort of half shift. The chain stays where it is and the system gets stuck, I am unable to continue shifting up until I shift back down one effectively reseting back to the gear I started in.
I honestly can't work out what the problem is, although since the frame has no outer stops it's a full length of outer from the shifter to the mech, could simple friction be the issue? I have tried to ensure the system is kept clean and well lubed.
Any ideas what this might be? Anyone else had this problem?

 

[Squash]

Yes friction could....

easily cause the problem you are having. It sounds like the cable is dragging somewhere. It's very difficult to diagnose issues like this without being able to go hands on. But things to check, routing: check you're routing to make sure there are no sharp bends or loops in the housing. Any bends should be relatively smooth and as gradual as possible. Check the housing ends and make sure they are nice and round and that the ends are square, also check that the inner lining isn't squished out of shape on the ends. Remove the housing from the cable and check that the cable has no kinks or bends in it. A kinked cable will set up a signficant amount of friction. And finally, without cable stops how are you holding the housing inplace? Obviously with some from of clamp, zip tie, etc. Make sure that they have not been wrenched down super tight. While you wouldn't think so, derailleur housing can be compressed slightly from cranking down a zip tie super tight. This can slightly ovalize the inner lining and cause a bit of friction as well. Anyway, it's likely a friction problem. The tough part is finding where it's coming from. If it all checks out then it well may be an adjustment problem.

Good Dirt

 

[robc in wi]

I had this exact problem with my new X9 grip shifter/X9 rear der this summer and kept playing with the barrel adjuster. Turned out it was simple cable stretch. Put the rear in the smallest cog and check the cable tension. I pretty much went with tightening the cable by hand with a slight tug, tightened the clamp and it's been great ever since.

 

[duclicsic]

Yes the outer is fixed to the frame with cable ties, they're not overly tight but I'll certainly look at just binding them loosely for a while to see if it stops. This is all brand new kit, shifter, mech, cables, the lot, and it's been happening since I built it. I cut all the cables myself with proper cutters and checked the ends of the outers for any faults, installed the little caps on the ends and made sure everything was routed in such a way as to avoid sharp bends or undue tension.
I have to say the system doesn't feel like there is any more friction than there should be, and the fact that it sort of half shifts was making me lean towards a problem with the shifter. Can these things be rebuilt without springs flying out and being lost to the darkest corners of my basement?

 

[frdfandc]

Since you are using a short cage derailleur, are you running a single chainring up front?

What is your entire drive train?

Chain ring count with tooth count?

Cassette size

 

[Squash]

Check to see...

if it's just one gear/cog on the rear that's doing it, and which one it is. I recall that there were some early production 09 990 and late production 08 990cassettes that displayed this problem in the 5th or 6th cog. Slightly out of spec in some way. The teeth of the cog just didn't like to release the chain for some reason. Once the cassette was worn in a bit it went away for the most part, but it took a bit of riding. And it was certainly a pain in the butt during initial set up. Could be the problem.

Good Dirt

 

[duclicsic]

Yes it's a single ring on the front, a raceface 38 tooth. It's a PG970 11-34 cassette and a PC991 chain. The problem occurs when shifting up a gear and seems to be able to happen mostly going from 4 to 5, or 5 to 6. However I have noticed that it doesn't tend to happen unless I've not changed gear for a little while, lots of quick shifts right and and down the range never seems to reproduce the issue.
It pretty much always happens when I've just left the house, as soon as I get some speed up and want to change gear accordingly, I shift, and it sticks. I could easily then shift up and down 50 times and not see it happen again. Then if I go some distance without a shift, I'll go to change up one again and once again it sticks.