agenkin

I am experiencing the same issue on two different bikes. One has a Deore M592 RD, the other has a Sora 3500 RD. The issue is exactly the same.

With shifter cable completely detached and the limit screw properly adjusted, the RD does not return to the outmost position (smallest sproket) on itself. If nudged by hand, it returns just fine, so I don't think that the limit screw setting is to blame. It's as if the spring is not strong enough and does not pull the derailer hard enough.

On my third bike with an XT M8000 RD everything works properly. I use the exact same procedure to adjust RD on all three bikes.

Is there something that I am can try to improve this? Thanks!

dsbrantjr

Clean and lubricate the mechanism, perhaps?

markjenn

I've had the same issue on several bikes.... the shift to the smallest cog is where the return springs are at their weakest and so there is less headroom to pull the cage closed - it's also where you're probably cross-chaining to some degree which aggravates things. Things were always solved if I remove the RD, cleaned it thoroughly and really lubed it well, but over time it may start hanging up again. For a couple bikes, I've punted and just replaced the RD.

I guess I'm just sympathesizing and saying the problem is fairly common rather than giving you a solution - the only thing you really can do is check alignment and make sure things are clean/lubed. And speaking of alignment, I bought the Park RD hangar alignment tool a decade ago and it has really helped shifting on a few bikes. It doesn't take much mis-alignment of the hangar to cause issues.

- Mark

Andrew R Stewart 

Since Shimano went the soft cable pull path this is a known issue. The parallelogram return spring suffers over time. Some will claim it's only pivot friction but I have seen this in many ders with freely moving pivots. I've replaced more then a few rear ders and solve this after trying the usual cable stuff. Andy

shine2000

wash the whole bike and clean and lube everything.

bikeaddiction1

Typically this happens when the shifter cable gets worn or dirty. As other posters say this is the weakest point in the return spring on the derailleur, and if there is cable drag it reaches a point where the spring doesn't push all the way. Try shifting all the way down and when it does not go on to the smallest cog, release the shifter cable at the derailleur and see if the derailleur moves out and completes the shift.

If it does you can play around with cleaning and lubing the cable but in my experience this is just a stop gap procedure. It may be time to change the cable and housing. It is amazing how much better shifting is with a new cable and housing.

fietsbob

buy a new RD. & cable, housing , check alignment of hanger.

alcjphil

The first post clearly states that this condition happens with the cable disconnected. Thus, this answer is of limited value

alcjphil

Obviously, you didn't read the question

alcjphil

The only thing I can think of if your derailleur is in good shape is possibly alignment of your derailleur hanger. I admit that it may be a bit of a long shot, but it could be an inexpensive fix. More expensive would be if your derailleur has been bent inward somehow. However, unlikely to have the same problem on 2 different bikes. you should treat them as 2 separate cases. The solution for one may not apply to the other

fietsbob

Bring it by? the LBS is very quiet in the winter..

agenkin

Thanks, everyone. I think I should take the derailers off for really thorough cleaning. They are both about 2 years old (guessing about 5000 km of riding on each one). I've been cleaning and oiling them on the bike, but perhaps that's not enough. Will also check hanger alignment.

Not so happy about the prospect of replacing 2 year old derailers. What's the best quality rear derailer compatible with Shimano 9 speed STI shifters? I see that 9 speed Deore XT M772 derailers are still on the market.

markjenn

Nothing beats taking the RD off the bike, hosing it down with something like WD40, and working it back and forth lots and lots of times to flush the pivots. Then wipe it as dry as you can and lube with your favorite lube - I use Tri-Flow.

- Mark

Random Tandem

I know that is the kind of activity that gets me though the dark and wet season when riding is more difficult. Sitting down with a shot of tri-flow...

Kapusta

ExpertTools

9-Speed XTR?

Andrew R Stewart 

I had a thought about this thread last night. If the guide pulley has developed too much rock (some end play is proper but almost no rocking) then it will just flop towards the cog the chain is being shifted off of. Once the chain has shifted the pulley will realign to look straight and normal. This means some overshifting will be needed, easy to do when shifting to a bigger cog but not so when to a smaller cog. Andy

agenkin

My thoughts on this is that 9-speed XTR is older design than 9-speed XT, which, in its turn, is older design that 9-speed Deore. It is possible that a 9-speed Deore derailer is actually a better design than the 9-speed XTR, even if I manage to find the XTR new old stock somewhere. On the other hand, the manufacturing tolerances and materials may be better on an old XTR than on today's Deore. So I don't know if a 9-speed XTR would be an upgrade from the 9-speed Deore. Would it?

agenkin

Thanks, Andrew, that's an interesting thought, worth investigating. However, I *think* that this is not the problem because the derailer does not actually move all the way to the right on its own. It should return all the way to the right until the limit screw stops it.

So, things to investigate so far:

• Does the problem exist with the chain removed?
• Try removing the derailer and cleaning the living jeesus out of it, then lubricate well.

Things that I don't think are the main cause of the problem (because the derailer visibly does not return to the outmost position), but still worth checking:

• Check hanger alignment.
• Is there play in the guide pulley?

Mitkraft

I was having a very similar problem with my road bike when I first built it. Took it to my friendly LBS guy and he identified the problem pretty much before even seeing it. I had the little nub on the cable retention assembly rotated 90 degrees and the little nub was on the wrong side and getting in the way such that it was stopping the derailleur from fully collapsing. I know you said you removed the cable, but is the cable retention assembly still connected and is that nub possibly in the way?

NJgreyhead

In the future, you might try leaving the chain on the smallest cog when you are done riding for the day, to help retain or restore the derailleur spring's original relaxed / unloaded / unstretched position.

agenkin

I finally had a chance to take the derailer off and clean it. I'm pretty sure that the problem was that the spring was dirty. When the derailer is in its natural right-most position, the spring is supposed to be completely compressed. But road grime that was stuck to the spring was preventing the winds from coming together completely.

When I removed the derailer, the limit screw would not touch the stop, unless pushed further by hand. After I thoroughly cleaned the spring, the derailer now returns far enough for the limit screw to touch the stop. Cleaning it was pretty inconvenient. I had to keep the spring stretched with one hand and clean the spring with another. Could not come up with a way to somehow block the derailer in the position with the spring fully stretched.

This explains why the derailer needed a nudge to go into the smallest gear.

I wonder whether it's best to keep the spring oiled or dry. Oil will probably encourage the road grime to stick to it.

easyupbug 

[QUOTE=

I wonder whether it's best to keep the spring oiled or dry. Oil will probably encourage the road grime to stick to it.

[/QUOTE]
As some mentioned above, Dri-Slide has many very good applications on your bike, cables, RD, FD, lever pivots, etc.

Kapusta