Bicycle Mechanics - M570 LX derailleur question

Hi:

I have an LX rear on my MTB and it just does shift right. Any slight bump will through it off and he end result is sloppy shifting. I am wondering if anyone else has had this problem as well.

Symptoms
-When selecting a gear, it doesn't always engage right away... instead it will do it in a second or so.
-There appears to be slack in the chain... I notice this when I pedal backwords after a gear was engaged and the chain slaps all over the place.... Sometimes it is nice and tight though.

I recently had a tune up done and it sorted it out but after a few trail rides and some very minor bumps the problem is back.

Any thoughts?

I ran a bike with Acera for many years before this and never had any problems...

It sounds to me like your derailleur needs a cable tension adjustment. Since you said that you have had a recent tune up that solved the problem temporarily, I suspect that you have a shift cable housing problem. That's a semi-common problem.

Look at the cable stops on your frame. Do you see any tiny wires sticking out? That's an indication that your cable housing end isn't doing it's job and the cable housing gradually shortens and screws up your shifting. If that's the case, replacing the cable housing end will fix it.

Thanks for the response Retro Grouch

The cable housings look fine. In fact the bike is only one year old.

If you have actually checked them out and are sure they're good, cool. But, don't assume that the housings are good just because it's new or new-ish. Most of the cable housing problems I have had were with new bikes. A couple of them had derailleur to frame loops that were too short, one didn't have a cable end on one end of the frame-der loop and the wires came poking out in fairly short order (as R-G mantioned), and a couple had kinked housings - probably from shipping or handling in the shop.

All that said, R-G is probably right that the cable tension just needs a bit of a tweak. If you have a good shop that did the tune-up recently, you can probably talk them into a quick adjust for free as long as that's all it needs. Also, make sure the derailleur and the idler pulleys are free of gunk.

Thanks for the response Retro Grouch

The cable housings look fine. In fact the bike is only one year old.

It's the inside of the housings that you are concerned about. Have you looked there? You can take the housings out of the stops with the cable still attached in many cases and run them up and down the cable to check for friction.

Your cable pulls on your derailleur the prescribed amount when you shift. The prescribed amount is dictated by your cable stop and your shifters. (cable tension) I think you don't have your cable tension right either. If you don't know how to do it, go to www.parktool.com or www.sheldonbrown.com and learn how or take it back to your LBS.

Could definately be housing issues. Many new bikes I see at the LBS have the housing setup improperly: too much/too little housing between cable stops. Many times replacing cables and housing will have a dramatic affect on the performance of one's bike.
Also:
Is the derailer screwed in tight?
Is the derailer hanger or cage bent?
Are any of the rear cogs bent/damaged?
Is there any play in the rear hub?

Once again thank you for all the input.

I've checked the cable and housing and both are in great shape... I've also added a bit of Pedro's for good measure. After two counterclockwise clicks of the barrel adjust ment the shifting is much better.

However the problem with the chain remains, and it's the worst when in gears 7-9...... it appears that the RD really flexes a lot at the joint where spring number 10 sits.

it appears that the RD really flexes a lot at the joint where spring number 10 sits. So........................?