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nrs ghost shift under load????

924 views 14 replies 8 participants last post by  AndrewTO 
#1 ·
01 nrs ghosts shifts under load. brand new drive train ... XT, XTR chain TRUVATIVE STYLO CRANKSET.... what now??? deal with it? or is there a simple fix?

thanks, ben
 
#2 ·
maybe post up a photo of your cabling, particularly the outer cabling as it passes from the toptube to the seatstay.

are the ends of the outer cables firmly and fully inserted into the frame lugs? any slop there can lead to probs.

:)
 
#3 ·
The NRS design "tops-out" the suspension during hard pedaling (giving it that hardtail
like snap) This can also add slight tension to the rear derailleur cable causing ghost shifting.

Slightly decrease the cable tension at the barrel adjuster on the shifters, or on the derailleur.

Or, possibly due to cable routing, tension may be going slack slightly - in this case
just add a bit of tension with the adjuster.

Either way, it is definitly a cable tension adjustment problem.

I used to have a ghost shifting NRS myself, but it's smooth running now :)
 
#4 ·
One more thought

deoreo said:
The NRS design "tops-out" the suspension during hard pedaling (giving it that hardtail
like snap) This can also add slight tension to the rear derailleur cable causing ghost shifting.

Slightly decrease the cable tension at the barrel adjuster on the shifters, or on the derailleur.

Or, possibly due to cable routing, tension may be going slack slightly - in this case
just add a bit of tension with the adjuster.

Either way, it is definitly a cable tension adjustment problem.

I used to have a ghost shifting NRS myself, but it's smooth running now :)
If possible, make these adjustments from the barrel adjuster on the shifter while riding. Saves a lot of time getting off the bike, adjusting the barrel on the derailler, get back on the bike, skips again, repeat process, etc., etc.

Get my point?

Bob
 
#5 ·
laackund said:
01 nrs ghosts shifts under load. brand new drive train ... XT, XTR chain TRUVATIVE STYLO CRANKSET.... what now??? deal with it? or is there a simple fix?

thanks, ben
i have heard the rear end on the earlier model NRS' are flexy, which changes the cable tension (the cable stops on the seatstay either get closer or farther away). try running full housing from the back of the top tube all the way to the derailer, and make sure the loop at the end of the seat stay to the derailer is big enough. 2004 model NRS' had full length housing just as i described for whatever that's worth.
 
#6 ·
i have an 01 nrs and it is very flexy (and creaky when dirty). but i've never had a problem with ghost shifting. instead i have a problem with the chain falling off the small chainring when riding over rocky terrain. even with the limit screw set correctly and plenty of tension on the chain, it will fall off if i'm bouncing around enough.
 
#7 ·
To add to the numerous good points;

full length RD cable housing has been a fix as reported by some

changing to a SRAM shifter/RD combo has also had good results

NOT saying that either will/won't work, but something to look into when the other options are un-successfully exhausted.
 
#9 ·
angryasian said:
What about the other years? Did Giant only have this problem with the early year's? I know about the difference's with the dropout locations, but what about the rest of the seatstay?

Don't get me wrong - I believe what you say, that's why I posted what I did. I just wanna know about the rest of the line. I'm still learning about it. ;)
 
#10 ·
AndrewTO said:
What about the other years? Did Giant only have this problem with the early year's? I know about the difference's with the dropout locations, but what about the rest of the seatstay?

Don't get me wrong - I believe what you say, that's why I posted what I did. I just wanna know about the rest of the line. I'm still learning about it. ;)
Giant changed the rear end design in '04. I haven't heard much about ghost shifting issues after the change so it's likely that the seatstay has been stiffened up. If you have one of these later models but still have ghost shifting issues, it would be easy enough to temporarily bypass the seatstay housing stops just to check it out.
 
#11 ·
angryasian said:
Giant changed the rear end design in '04. I haven't heard much about ghost shifting issues after the change so it's likely that the seatstay has been stiffened up. If you have one of these later models but still have ghost shifting issues, it would be easy enough to temporarily bypass the seatstay housing stops just to check it out.
interesting. i have an '05 NRS, otherwise the same as the '04. the outer cable/housing is already 1 piece, from the toptube all the way to the RD, so it seems Giant addressed this issue with the exact fix that's been suggested.

a quick look through the Giant archives of NRS's, and indeed the pre-'04 models feature a 2-piece outer cable housing: toptube->seatstay and seatstay->RD.

:)
 
#12 ·
angryasian said:
If this is the case, how is it that on my 2001 NRS I had to decrease cable tension
to eliminate the ghost shifting?

Set up normally, I had no problem on flat, rolling terrain, but any significant steep
caused ghost shifting.

I have a very steep granny ring hill in my back yard, so I could really get to the
bottom of this problem. While pedaling up this hill, I could actually watch the
cassette and see the chain want to skip to the next lowest gear (ie: up the cassette).

So I had to slightly decrease the cable tension, since I did that it has since worked
perfect.

My take on this, (but I am not an engineer) is that because pedaling forces try
to top out the suspension, the seatstay is bowing, but the cable stops are
being pulled apart - think of the dropout being pulled towards the seat tube.

So I still say, try the cable tension first, but a full outer rear cable is also a solution.
 
#14 ·
sorry it took so long to answer replys, out of town for the weekend.... anyway, after reading posts this morning i checked it out in the kitchen. i locked out the fork and brakes; when i stood on the pedals and tried to drive them forward, i could see the chain stay bowing outward a little bit. it seemed to be the most pronounced at the pivot below the cassette. the non drive side bowed some too, but it didnt appear to as much. after taking off the wheel and dismantling half of the rear triangle, i isolated that pivot to look for any play. no lateral movement, seemed to move in intended direction w/o any extra friction.... i havent tried the full length housing yet, would you suggest just using zip ties to keep it in place? also i dont have a digital camera, but ill see what i can do about borrowing one.

thanks for the help... hopefully this helps narrow things down
 
#15 ·
laackund said:
sorry it took so long to answer replys, out of town for the weekend.... anyway, after reading posts this morning i checked it out in the kitchen. i locked out the fork and brakes; when i stood on the pedals and tried to drive them forward, i could see the chain stay bowing outward a little bit. it seemed to be the most pronounced at the pivot below the cassette. the non drive side bowed some too, but it didnt appear to as much. after taking off the wheel and dismantling half of the rear triangle, i isolated that pivot to look for any play. no lateral movement, seemed to move in intended direction w/o any extra friction.... i havent tried the full length housing yet, would you suggest just using zip ties to keep it in place? also i dont have a digital camera, but ill see what i can do about borrowing one.

thanks for the help... hopefully this helps narrow things down
Some have suggested using either zip ties or opening up the cable stops with a dremel. Myself I can't say because I don't have much time with this mod, but i'm trying the zip-tie method first simply because I don't like permanent mod's unless I know they're worth it (my weight and riding style may not necessitate this mod for all I know).

Cable, housing and zip tie can all be had for cheap - especially if you snagged a couple of zip tie's while you were in the kitchen. :p :D ;)
 
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