Problems with SRAM Attack + XT rear der.
I just got a new rig (Yeti 575) with XT rear der. and SRAM Attack shifters. I'm having problems with shifting on the rear. When I shift to a higher gear (i.e. smaller cog) in the rear, everything is crisp and fine. However, when I shift to a lower gear (i.e. larger cog) in the back, the chain skips around, and doesn't seem to want to settle into gear. It's especially bad when really hammering hard, e.g. climbing. No amount of playing with the barrel adjusters seems to help. The guys in my LBS said something about "full length housing = bad" and that "SRAM Attack doesn't work well". I've run SRAM 9.0 on my old bike and LOVED it. HELP ME- this mis-shifting is driving me NUTS!!
Assuming that you are using all new cassette and chain, I can only think of 2 things going wrong here. 1) Chainline maybe off or 2) The overtravel limit adjustment on the derailleur is set too tight.
If this is worst in the "Big-Big" combo (big chainring and big cog) could be your chainline is too far out. If the granny-granny combo works problem free, i'd say live with it and don't crosschain anymore.
Parktools has a good description on how to adjust the rear derailleur. If its none of these then ya could be the cables. You using a normal high derailleur? I could see the cables messing with the big cog there but not with the old style normal low.
This doesn't make a lot of sense to me- if the chainline were off, then why would it shift from larger cogs to smaller cogs with no problem? Also, I should be clear: the problem occurs in almost any gear, not just the granny. It occurs anytime I shift from a smaller cog to a larger cog. I'm pretty sure it's a normal high.
Originally Posted by Ratt
Oh i misread "larger" cog as "largest" cog. But a chainline too far out tends to pull the chain off the larger cog to the smaller cog or chainring too easily, especially if they are worn.
Originally Posted by Puzman
Ok theory #3: you have binding in the cable somewhere (at the derailleur, housing, cable itself, or at the shifter). Maybe one of the cut ends of the housing was not cleared properly and is slightly crushed or the cable is just not moving freely. This would be consistent with a "rapid rise" rear derailleur because to shift to the larger cogs you release cable (needing free movement) and to go to the smaller cogs you take up cable (the tension will over come the binding).
Theory #4: You are experiencing ghost shifting, when the suspension moves ever so slightly the derailleur will move causing shifts or rattling like it wants to shift. Usually this is caused by making the loops where there will be movement (mostly main frame to rear triangle) too straight. There needs to be loops in these areas to keep the the cable the same length throughout the suspension stroke.
My vote goes to #3, i have never seen a 575 up close so i don't know how the cables are routed but if you release the cable from the derailleur end and with your hand add some slight tension to the cable, shift through the gears and see if you can perceive any binding as you shift up and down. Shift to your largest cog and slide the cable housing back and forth over the cable and see if you can perceive any binding
Full length cable housing is the best way to keep a cable clean and shifting smoothly in muddy enviroments. When I was running V-brakes i ran a full length shifter housing in the hydro brakeline holders on my frame, it shifted fine.
Here's something to ponder;
Gripshift started with 2:1 cable actuation. Because they were (and still are) made of plastic, they would wear fast, and the 2:1 actuation would MAGNIFY the effects of this wear and result in crappy performance.
This is why SRAM went to 1:1 actuation, it better masks the deficiancies of plastic internals and detents. Wear is no longer "magnified" and while it will still happen, it will simply take "longer" to wear out.
So when you go back to attack/rocket shifters, you very well may not get that same performance that you got with ESP.
I'm sure your setup CAN work fine, but any problems in it are going to be magnified as a result of this 2:1 actuation.
There's a lot of trouble shooting required to fix problems like these.
Check derailer/hangar alignement.
Replace rear loop.
Replace all cables/housing.
Replace cassette to troubleshoot current cassette (sometimes you get one that just doesn't want to shift, happened last week).
I know in my heart that Ellsworth bikes are more durable by as much as double. AND they are all lighter...Tony Ellsworth
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