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Ghost Shifting / Chain Jumps on cassette

2K views 15 replies 8 participants last post by  jonathancarlos 
#1 ·
I’m really hoping someone has some insight or advice on what to look for here.

The bike: 2006 IronHorse MKIII.

A Few drive train upgrades you should know about in case someone thinks it will make a difference.
LX HollowTech Cranks
DT Swiss 5.1/340 Wheel set
Shimano Dual Control hydraulic Disc brake / shifters levers.
XTR rear derailleur

The problem: In late December of 2007 the chain started to jump or Ghost Shift.

First Trip to a local bike shop, Replaced:
Chain
Cassette
Middle Front Chain Ring

Still Ghost Shifts…

Next trip to the local bike shop, Replaced:
Rear Derailleur (new XTR)
Derailleur Hanger

Still Ghost Shifts…

Next Trip…
Another New Chain… Then a 3rd (this time we tried a Shimano chain since everything else is Shimano).

Still Ghosts Shifts…

A trip to another local bike shop.
The mechanic feels the other shop cut the derailleur cable and housing to short before the barrel. So I replaced the cable and lengthened the housing before the barrel of the derailleur.

Worked great for about 40 miles… now Ghosts Shifts intermittently… no where nearly as bad as it was… but problem still exists…

I check my Chain Line last night: Front 50mm / Rear 38mm.

What should I be looking at next? What am I missing?

Thanks,
JC
 
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#5 ·
Yeah… I’ve really done a lot so far… but I’m determined to track it down. After I replaced the cable and put more length on the house between the last cable stop and derailleur the bike ran perfect for about 40 miles then jumped on me. So I adjusted the cable (it had stretched) and check the alignment on the derailleur hanger. Took it out for about 3 (10 miles each) loops at Laguna Seca over the weekend and it was erratic on the first loop, jumped about 3 times on the second loop and was perfect on the 3rd loop. So you can see it’s something intermitted.

Last night I took the shock off and ran the suspension through its range. Got no movement out of the derailleur… so I scratched that off my list.

My task tonight is I’m replacing ALL the housing with new Jagwire housing with new cable ends (the ones with brass inserts). Might have something binding up in the housing.
 
#7 ·
Yes on all. Had rear sway arm checked. Took my wheel down to a shop that I only use for Wheels… he’s good with wheels. He took apart my DT Swiss 340 hub and replaced the nipple… all looked good. The cogs are snug sided to side… but they do have a little play before engaging on the freewheel.
 
#10 ·
You've replaced the chain enough times to rule that out, but it's always important to ensure that all the links are good.

The derailleur MUST be moving. You've checked the frame and derailleur hanger for issues...
You had an improvement when you replaced some cable housing. So continue to look at the cable and shifter.
 
#12 ·
Tension the cable using the shifter adjustment until it is all aligned nicely.

Also if it only happens under a lot of pedaling stress, consider frame/pivot flex (I dont know if that bike is full suspension, just throwing out ideas) because the chain has a tendency to pull the right side of the swingarm towards the front.
 
#13 ·
I appreciate all the input here.

The update is I went ahead and replaced the rest of the house since I had only replaced the housing from the last cable stay and the derailleur. But the kicker is when I took the new housing piece off that I had just replaced… the end was messed up. So it was good to find something. Took it out for a quick 12 miler last night and tweaked on the cable tension until it ran pretty good. So I hope it’s down to just fine tuning now.

Keep you posted...

Again… thanks for everyone who’s jumped in.

JC
 
#14 ·
if it still isnt shifting well or ghost shifting-a severe problem could be flex in the rear stays. i crashed my bike hard and the left rear stay smacked hard into a rock. Got bent in a little and was flexing. It was time for a new drivetrain anywat so i put that on and it was still 'ghost shifting'. new frame was needed. Hoefully this is not the problem but it could be the cause if youve had a significant crash.
 
#16 ·
Not getting any better. Just got back from another ride and the chain was still jumping… a couple were real bad… did a complete shift. I look down in time to see it shift back in to the proper gear. Jumped to a larger ring... This means it had to pull on the cable. Not sure where to go from here. I’m wondering if having a normal rise derailleur on this DC system is a problem.


Chrisdp9... how did you check the frame for flex? Because I've tried to move the frame around and everything seems snug?
 
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