Another shifting nightmare!
I see lots of shifting problem threads here and I have read them all but none of them seem exactly like what I have going on with my ride.
My rear drivetrain consists of shimano XTR 970 rear der, 7701 chain, 970 cassette, 970 dual control shifter/brake levers, Jagwire cables & housings.
So far, I am not thrilled with the 970 line verses the 960 line. The 970 stuff is super temperamental. It's never really been consistant in shifting and it's getting worse. My old 960 stuff was much more reliable.
All of the above componants are 6 months old or less, the chain is about 2-3 months old. I only ride a few times a week, moslty 10 miles or less. I do not go thrashing through creeks.
OK, the specific problem. No matter what I do, I cannot get the rear der to shift smoothly up or down. If I get it adjusted to shift smoothly up onto one cog at a time, it will skip 2 cogs going the other way. If I get it to shift smoothly one cog at a time going down, it will skip 2 cogs going up.
1) The upper pulley on the rear der seems to have an aweful lot of back and forth play for how young it is. It will move back and forth on it's bearing a good 1-2 millimeters. The lower pulley has no unusual play.
2) The rear der itself has about 3-4 millimeters of back and forth play when rocking it from the lower pulley area.
3) It seems like the shifter has 10 shift positions??? When I shift through all of the gears, it seems to be able to shift one more time, a dead shift.
4) The skip shifts occur from the largest cassette cog to the third cog. Like the problem could be related to the second largest cog? It happens going up or down.
The hanger is not obviously bent but I have not used a tool to really check it out. I carefully checked every link on the chain and found smooth even tension throughout.
A visual inspection of the cassette and rear der cogs found no bends, wear marks or breaks on the teeth. I keep the drivetrain clean. It's usually glistening w/o build up.
The hanger is not obviously bent but I have not used a tool to really check it out. I & The skip shifts occur from the largest cassette cog to the third cog. Like the problem could be related to the second largest cog? It happens going up or down
I would still check it with an alignment gauge - I bet this will be out, and is the main problem. Wouldn't hurt to check the B-tension here too. This little bugger can affect your shifting in the low gears if not set up properly
Jagwire cables & housings
Could be the problem. Not Jagwire itself (I prefer Shimano myself - sp-41), but you bike might need new cables and housing. Lots of friction in the system might be preventing it from shifting properly
The upper pulley on the rear der seems to have an aweful lot of back and forth play for how young it is. It will move back and forth on it's bearing a good 1-2 millimeters. The lower pulley has no unusual play.
Nothing here to worry about
The rear der itself has about 3-4 millimeters of back and forth play when rocking it from the lower pulley area
Hmm, you could try a new RD to see if this is the problem - should be fine
A visual inspection of the cassette and rear der cogs found no bends, wear marks or breaks on the teeth. I keep the drivetrain clean. It's usually glistening w/o build - carefully checked every link on the chain and found smooth even tension throughout.
DT 6 months old and clean - I think you might be O.K. here too. Again, have the hanger looked at first before spending big $$ on a solution
Cort gave you good leads as to the possibilities. It's really hard to diagnose drivetrain problems sight unseen, so I suggest you work on all his ideas one at a time from the simplest/cheapest onwards to the expensive complex.
As he said, play in the upper pulley is designed in, and normal.
Try this test to check for sluggish cables. Starting from a mid range cog upshift (towards smaller cog) one position. Note the trim, then pluck the bare wire away from the frame like a guitar string, and see if the trim changes. Repeat this a few times from different gears to establish a pattern.
If plucking changes the trim it's because the wire is binding someplace, either because of overly thick lube in the housing or lever, or because of frayed wire or worn housing. Dis-assemble and examine carefully. Lube the housing only with the lightest oil you can find, and re-assemble. If you can, reverse the HB/Frame length of housing so that the curve is in a new place bringing what is essentially new housing into this wear zone.
For the movement of the RD on the hanger bolt, wind dental floss into the space to act as a filler and stabilize the RD. If that works, you'll have to improvise a permanant solution, or replace thr RD.
Hanger allignment needs a tool or the LBS, so I'd save this for later unless you've crashed. Hint- if the RD is scuffed or scraped on the outside, the liklihood of a mis-alligned hanger is greater, and you should move this to a higher priority.
Good chain lube is also a must. There's a spectrum between a well lubed supple chain and one with stiff links. Even without visible stiff links a chain can perform poorly on smaller cogs which have limited engagement.
The key to solving any problem is to understand and address the underlying cause.
Update: It's Fixed!!!!
I decided to stop by my LBS and pick up some new cable and housing. That's a cheap investment that can only help...
Upon removing the old cable and housing, I found the absolute problem.
The cable was indeed hanging up in the housing but more specifically, one of the housing end cap openings had deformed severly and was grabbing the cable. The cable and housings looked fine but I replaced them anyway.
This also explains why the cable would go super slack and then jump 2 gears at a time when shifting or not change the gear at all when the shifter was engaged.
My ride now shifts buttery smooth. I have had this problem in the past. I will remember this exact resolution and apply it when this happens again...
See, I'm learning little by little!
My LBS is selling thin, cheap housing end caps, LOL! They don't last long at all...LOL!
Now that the problem was in the Jagwire cable and housing, does this statement still hold true?
Originally Posted by ambassadorhawg
I find the new 970 stuff to be rock solid, when installed and tuned correctly.
IMO, no. 970 XTR is not as reliable as 960 was for me. XTR is fairly temporamental compared to XT, it needs readjusting more often and performance is definately effected by any build up on it's parts. I compared 970 parts vs. 960 parts while I was switching them out and I could see that the quality was not the same. Plus, I can already detect wear on the 970 rear derailleur after less than one year of not so consistant riding. My 960 stuff lasted 4 years!
Originally Posted by senna
970 does not shift as smoothly as 960 did. Big proof is how Specialized switched to high end Sram as opposed to high end Shimano derailleurs.
However, let me pull my foot out of my mouth now because I love reverse shifting (low normal) and therefore I am sticking with XTR.
The Big S switching to SRAM was more the situation of a purchasing agreement than anything to do with performance of the product. Both SRAM and Shimano make great stuff, some like the way one works better than another, etc... but when you buy kit for as many bikes as Specialized or Trek, et all.., bikes tend to get equipped as much by the accounting dept as by the engineers. All the advice in this thread was pretty much dead-on - check cables, hanger alignment (esp where the hanger is "straight" vertically but may have a slight right-left twist - only a few degrees can really mess up a 9 or 10-spd system). I always made a habit of replacing cables on my geared bikes each year. They're cheap unless you buy the "system" cables that IMO don't seem to work much better than the better-quality "regular" cables.
I wish I could go as long a s a year w/o new cables & housings!!! For the past few years, I've had to replace them about 3 times a year!!! WHY IS THIS HAPPENING??? It's seems if I go through one little creek, I am doomed to get a net set of cables and or housing soon thereafter!!!! WHY IS THIS HAPPENING????
Originally Posted by ATBScott
I did not mean to say that SHimano stuff is junk. I will always be a Shimano diehard. It's just that EVERY magazine I read say that Sram rear derailleurs shift just a little bit smoother, that's all. When you read something in print for the WHOLE WORLD to see, you tend to think it's the wide belief of most. I never think of a statement like that as the singular opinion of a writer....
Try running full length housing to see if that makes a difference.