Rear derailleur won't move to small sprocket

solarflash

I've got an x.7 rear derailleur, I've got the stops set up ok, but even when theres no cable tension the mech won't move to the smallest sprocket unless I give it a nudge with my hand. I've tried working the mech and spraying with lube to free it up, but it hasn't improved. It also gets stuck on the largest sprocket too. Any advice how to fix it, or is it time for a replacement? It's over a year old and has been used for commuting daily as well as mtb duties.

nicklouse

sounds like either too much cable tension or your stops are not set correctly.

what do you mean by stuck on the lagest sproket?

Or your mech hanger/mech is bent.

solarflash

Hey Nick, thanks for the speedy response!
I've tired taking the cable off and moving the mech freely, when it springs back it doesn't travel all the way to the smallest sprocket, if i nudge it with my hand it does. The H screw is uncrewed just about all the way out at the moment.

When I shift up to the largest sproket, and then back down, the mech fails to move outboard on thew way back down, unless I move it with my hand, then it works.

supersonic

Try lubing the pivots on the mech.

or the spring is knackered.

chriskempton

Have you put the cable clamp bolt on the right way? I had a similar problem (admittedly with a Shimano road mech) and it took me a long time to figure it out. I had the clamp bolt on the wrong way :roll: although it still clamped fine, and the clamp bolt was catching the cage and stopping the mech going to the smallest spocket without a nudge. Your issue just rings a bell.

solarflash

oooh that sounds like it might be part of the problem Chris. Haven't paid much attention to the clamping bolt, hmmm will investigate further...

Cheers supersonic, yeah was lubing like a manic and moving the mech back and forth trying to free it up last night.

nyanza

The 'nudge with the hand' bit sounds very familiar to me too, and suggests that cable might be getting stuck in the outers. I replaced the rear mech cable for a new one and problem solved. If you still have a problem then replace the outer. My LBS gave me that short bit at the back for nothing as it was an off-cut.

The Rookie

easy enough to loosen teh cable and ease an outer end from a stop, make the cable slack and see if it now moves freely, if not its def the cable!

Cheap cables available from Wilkinsons if you're tight!

Simon

supersonic

He said he had released the cable.

Sounds like a gunked up mech or poor spring.

nicklouse

supersonic wrote:

He said he had released the cable.

Sounds like a gunked up mech or poor spring.

very hard to gunk up a sram mech unlike a shimano one.

and a poor spring? i would be seriously suprised if it was after just one year of use.

But with having it in my hands it is hard to say.

just check that when it is in the small cog position that there is nothing between the base of the stop screw and the mech body (and it is not actually touching).

supersonic

Should see the state of mine.

Do you want it for free?!

;-)

nicklouse

you paying the postage?

supersonic

Not sweden, I'll send it to your parents.

Nah, I bent the cage on a rock, need to persuade it back lol.

nicklouse

Now that can cause shifting issues.

nyanza

He said he had released the cable.

Released? Or slackened?
As I understand it, SolarFlash's cable is all slack (ie you can grab a handful of it under the downtube) when trying to enter the last sprocket, but it still has to run through the rear mech housing outer. So, "no cable tension" means the shifter is in position 9, but the mech sticks at 8, causing slack, but then takes up slack when poked. When this exact same scenario happened to me it was because, for reasons unknown, the cable had developed a small kink (crushed at some point?) inside the rear mech outer. The kink only inhibited the movement in the housing when when trying to enter the lower and upper sprockets. A quick poke and the mech dropped down, and the cable slack was taken up. (N.B. Stops were all let out to max during diagnosis)

Still, it could be a dead spring, but then why does the mech not drop down from the largest sprocket when the spring is under the most tension? Therefore, the badly aligned mech clamp screw seems a likely alternative. However, if the cable had been released from the mech then this would have been spotted already?

supersonic

I was going on he said he had removed the cable ie 'taken it off' lol.

Though when on the larger sprockets this could of course be a problem with the cable.

nyanza

Ah! The cable's taken off in the third post, but not the first. My mistake.

cloudynights

solarFlash wrote:

I've got an x.7 rear derailleur, I've got the stops set up ok, but even when theres no cable tension the mech won't move to the smallest sprocket unless I give it a nudge with my hand. I've tried working the mech and spraying with lube to free it up, but it hasn't improved. It also gets stuck on the largest sprocket too. Any advice how to fix it, or is it time for a replacement? It's over a year old and has been used for commuting daily as well as mtb duties.

ive had the same problem with two x9 mech, my lbs smiled at me and said they would swap it free of charge for shim xtr i just have to pay for some new shifters £100

solarflash

Sorry for the slow update. Yup, I had indeed released the cable. Took it to a lbs, and after a couple of days they decided the mech is faulty and is sticking. Seems to get slightly better if you continually shift up and down.

He said the cause was most likely because I'm using the smallest sprockets far more that the larger ones (due to commuting on flat ground most days).

So new rear mech it is then :roll:

Btw I also have a new cable which hasn't helped.

cloudynights

dont buy sram