Ghost shifting in rear
11-21-17 | 08:43 AM
#1
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Joined: Jun 2015
Posts: 997
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From: Western NC mountains
Bikes: Trek Domane gen 5, Marin Gestalt X10, Diamondback Century 3. Marin Four Corners
Ghost shifting in rear
Just got a new Marin four Corners. It has a 50/36/30 in front and 9 speed 11/32 in rear.
I'm having issues on the rear. I shift down (to a larger cog) and oftentimes it drops up a gear (to a smaller cog) This has happened consistently and usually on the larger 4 rear cogs. I will shift to a larger and it will drop back to a smaller. Here's the weird thing. Sometimes after I physically shift, it will on it's on shift back and forth. In other words, I'm pedaling along and it drops to a lower gear, then back up then back down.
It is as if the derailleur is indexing BETWEEN the rear cogs and it can't quite decide which one it is supposed to be on.
So I shifted to the smallest cog, loosened the cable lock nut and pulled the slack out of the cable. Still does it.
So I'm thinking I need to make an adjustment on the rear barrel adjustment. (?)
Do I adjust the barrel to tighten the cable tension or loosen, and does it tighten by turning counterclockwise or clockwise?
I should mention the limit screws seem to be dead on.
I'm having issues on the rear. I shift down (to a larger cog) and oftentimes it drops up a gear (to a smaller cog) This has happened consistently and usually on the larger 4 rear cogs. I will shift to a larger and it will drop back to a smaller. Here's the weird thing. Sometimes after I physically shift, it will on it's on shift back and forth. In other words, I'm pedaling along and it drops to a lower gear, then back up then back down.
It is as if the derailleur is indexing BETWEEN the rear cogs and it can't quite decide which one it is supposed to be on.
So I shifted to the smallest cog, loosened the cable lock nut and pulled the slack out of the cable. Still does it.
So I'm thinking I need to make an adjustment on the rear barrel adjustment. (?)
Do I adjust the barrel to tighten the cable tension or loosen, and does it tighten by turning counterclockwise or clockwise?
I should mention the limit screws seem to be dead on.
11-21-17 | 09:30 AM
#3
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Joined: Feb 2012
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From: Rochester, NY
Bikes: Stewart S&S coupled sport tourer, Stewart Sunday light, Stewart Commuting, Stewart Touring, Co Motion Tandem, Stewart 3-Spd, Stewart Track, Fuji Finest, Mongoose Tomac ATB, GT Bravado ATB, JCP Folder, Stewart 650B ATB
To bring the rear der inwards (more to the lower gears or larger cogs) you do what is actually lengthening the cable casing. If the inner cable was fixed at both ends then it's tension would increase too. But since the cable is attached to a spring loaded end (the der parallelogram spring) the "tension" won't change much. What will change is the rear der's position WRT the controller's "click point".
This adjustment, what I call an index adjustment, is one of the most basic ones we do many times a day. It's an adjustment that requires no tools (we hope your bike has threaded barrel adjusters) and one that can be reversed as easily as it was changed. The key is to remember which way and how far you turned the barrel. If you can't remember then write it down. Seriously, because even pros will turn the barrel the wrong way sometimes.
So go ahead and try. If you can see the ends of the fixed and the rotating parts of the barrel you can actually see the increased length of the barrel's overall length. After making a barrel change, that is recorded/remembered, pedal the bike to see what result is gained. This process of trial a bit of barrel change then test the bike is far easier to do if the bike can be stationary and the rear wheel off the ground. (A loop of cord around the seat and a ceiling joist, a trainer stand with the resistance off, a repair stand, a friend) so you can pedal and also closely watch the der moving the chain over the rear cogs. The goal is to have the der pulley directly below each cog after each shift has been done. A slight push/pull on the der, when at this balanced cable adjustment, will start to scuff the next larger cog or try to climb off the cog the chain is on. Release the push/pull and the pulley re centers under the intended cog. If this is all done and using the controller (lever) but you can't shift into the lowest gear then your index adjustment is likely one whole cog off. So just reverse what you did. This is why you want to remember what you did, how much of how many barrel turns, so you can go back and try again.
Cable caused ghost shifting usually is a slowly degrading process. Ride by ride the cable/casing system is changing bit by bit and at some point the collective bits are enough to cause a skip due to the pulley no longer being directly under the intended cog. A sensitive rider can often feel this degradation before skipping has started and might only need to turn the barrel less then a full turn to keep up with cable "stretch" (actually casing compression). A rider who wasn't so sensitive or proactive might need to turn the barrel more then a turn, two or more turns suggest an extreme case.
If the skipping came on suddenly, and the rider is sensitive, then there might have been an incident like a fall down of the bike (I've even fixed bikes that were impacted by soccer balls and trash cans) may have happened and the entire rear der might have been bent inward. If this has happened then besides the, now, misalignment between the intended cog and where the bent der places the pulley there's also the chance that the der can now overlap with the spokes when shifted to the large cog. Not good! Most modern bikes have an attachment tab called the hanger that is purposely weaker then the frame, can bend under relatively little pressure and can be either realigned or replaced as needed.
There are other reasons that a bike will ghost shift but with a new bike these other causes that are extreme wear related are not likely to be at play (yet).
The OP said the bike is new. cable settling in is expected on a new bike. This is but one reason that LBSs will offer a free after sale service at no cost, to retune the bike after initial break in periods. If the bike was bought at a shop then I strongly suggest taking the shop up on this offer. Because there's a number of other aspects of safe and sound mechanical function that also are bedding in and should have an experienced hand correct/confirm their condition/tuning/adjustment. If the bike wasn't bought from a LBS, or the shop sucks and doesn't offer after sale service then the single best source for mechanical help is possibly Park's Big Blue Book. Andy.
This adjustment, what I call an index adjustment, is one of the most basic ones we do many times a day. It's an adjustment that requires no tools (we hope your bike has threaded barrel adjusters) and one that can be reversed as easily as it was changed. The key is to remember which way and how far you turned the barrel. If you can't remember then write it down. Seriously, because even pros will turn the barrel the wrong way sometimes.
So go ahead and try. If you can see the ends of the fixed and the rotating parts of the barrel you can actually see the increased length of the barrel's overall length. After making a barrel change, that is recorded/remembered, pedal the bike to see what result is gained. This process of trial a bit of barrel change then test the bike is far easier to do if the bike can be stationary and the rear wheel off the ground. (A loop of cord around the seat and a ceiling joist, a trainer stand with the resistance off, a repair stand, a friend) so you can pedal and also closely watch the der moving the chain over the rear cogs. The goal is to have the der pulley directly below each cog after each shift has been done. A slight push/pull on the der, when at this balanced cable adjustment, will start to scuff the next larger cog or try to climb off the cog the chain is on. Release the push/pull and the pulley re centers under the intended cog. If this is all done and using the controller (lever) but you can't shift into the lowest gear then your index adjustment is likely one whole cog off. So just reverse what you did. This is why you want to remember what you did, how much of how many barrel turns, so you can go back and try again.
Cable caused ghost shifting usually is a slowly degrading process. Ride by ride the cable/casing system is changing bit by bit and at some point the collective bits are enough to cause a skip due to the pulley no longer being directly under the intended cog. A sensitive rider can often feel this degradation before skipping has started and might only need to turn the barrel less then a full turn to keep up with cable "stretch" (actually casing compression). A rider who wasn't so sensitive or proactive might need to turn the barrel more then a turn, two or more turns suggest an extreme case.
If the skipping came on suddenly, and the rider is sensitive, then there might have been an incident like a fall down of the bike (I've even fixed bikes that were impacted by soccer balls and trash cans) may have happened and the entire rear der might have been bent inward. If this has happened then besides the, now, misalignment between the intended cog and where the bent der places the pulley there's also the chance that the der can now overlap with the spokes when shifted to the large cog. Not good! Most modern bikes have an attachment tab called the hanger that is purposely weaker then the frame, can bend under relatively little pressure and can be either realigned or replaced as needed.
There are other reasons that a bike will ghost shift but with a new bike these other causes that are extreme wear related are not likely to be at play (yet).
The OP said the bike is new. cable settling in is expected on a new bike. This is but one reason that LBSs will offer a free after sale service at no cost, to retune the bike after initial break in periods. If the bike was bought at a shop then I strongly suggest taking the shop up on this offer. Because there's a number of other aspects of safe and sound mechanical function that also are bedding in and should have an experienced hand correct/confirm their condition/tuning/adjustment. If the bike wasn't bought from a LBS, or the shop sucks and doesn't offer after sale service then the single best source for mechanical help is possibly Park's Big Blue Book. Andy.
Last edited by Andrew R Stewart; 11-21-17 at 09:33 AM. Reason: added item
11-21-17 | 11:56 AM
#4
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Joined: Jun 2010
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From: NW,Oregon Coast
Bikes: 8
With the redesign of hyperglide tooth profiles lowering tooth height, and the addition of stamping ramps in the sides of cogs,
the ghost shifting is a part of the side effects.. you using index shifting? check into your LBS,
first thing I'd check into is derailleur hanger being aligned , with the shop tool made for the purpose.
...
the ghost shifting is a part of the side effects.. you using index shifting? check into your LBS,
first thing I'd check into is derailleur hanger being aligned , with the shop tool made for the purpose.
...
11-21-17 | 01:19 PM
#5
Thread Starter
Senior Member
Joined: Jun 2015
Posts: 997
Likes: 61
From: Western NC mountains
Bikes: Trek Domane gen 5, Marin Gestalt X10, Diamondback Century 3. Marin Four Corners
To bring the rear der inwards (more to the lower gears or larger cogs) you do what is actually lengthening the cable casing. If the inner cable was fixed at both ends then it's tension would increase too. But since the cable is attached to a spring loaded end (the der parallelogram spring) the "tension" won't change much. What will change is the rear der's position WRT the controller's "click point".
This adjustment, what I call an index adjustment, is one of the most basic ones we do many times a day. It's an adjustment that requires no tools (we hope your bike has threaded barrel adjusters) and one that can be reversed as easily as it was changed. The key is to remember which way and how far you turned the barrel. If you can't remember then write it down. Seriously, because even pros will turn the barrel the wrong way sometimes.
So go ahead and try. If you can see the ends of the fixed and the rotating parts of the barrel you can actually see the increased length of the barrel's overall length. After making a barrel change, that is recorded/remembered, pedal the bike to see what result is gained. This process of trial a bit of barrel change then test the bike is far easier to do if the bike can be stationary and the rear wheel off the ground. (A loop of cord around the seat and a ceiling joist, a trainer stand with the resistance off, a repair stand, a friend) so you can pedal and also closely watch the der moving the chain over the rear cogs. The goal is to have the der pulley directly below each cog after each shift has been done. A slight push/pull on the der, when at this balanced cable adjustment, will start to scuff the next larger cog or try to climb off the cog the chain is on. Release the push/pull and the pulley re centers under the intended cog. If this is all done and using the controller (lever) but you can't shift into the lowest gear then your index adjustment is likely one whole cog off. So just reverse what you did. This is why you want to remember what you did, how much of how many barrel turns, so you can go back and try again.
Cable caused ghost shifting usually is a slowly degrading process. Ride by ride the cable/casing system is changing bit by bit and at some point the collective bits are enough to cause a skip due to the pulley no longer being directly under the intended cog. A sensitive rider can often feel this degradation before skipping has started and might only need to turn the barrel less then a full turn to keep up with cable "stretch" (actually casing compression). A rider who wasn't so sensitive or proactive might need to turn the barrel more then a turn, two or more turns suggest an extreme case.
If the skipping came on suddenly, and the rider is sensitive, then there might have been an incident like a fall down of the bike (I've even fixed bikes that were impacted by soccer balls and trash cans) may have happened and the entire rear der might have been bent inward. If this has happened then besides the, now, misalignment between the intended cog and where the bent der places the pulley there's also the chance that the der can now overlap with the spokes when shifted to the large cog. Not good! Most modern bikes have an attachment tab called the hanger that is purposely weaker then the frame, can bend under relatively little pressure and can be either realigned or replaced as needed.
There are other reasons that a bike will ghost shift but with a new bike these other causes that are extreme wear related are not likely to be at play (yet).
The OP said the bike is new. cable settling in is expected on a new bike. This is but one reason that LBSs will offer a free after sale service at no cost, to retune the bike after initial break in periods. If the bike was bought at a shop then I strongly suggest taking the shop up on this offer. Because there's a number of other aspects of safe and sound mechanical function that also are bedding in and should have an experienced hand correct/confirm their condition/tuning/adjustment. If the bike wasn't bought from a LBS, or the shop sucks and doesn't offer after sale service then the single best source for mechanical help is possibly Park's Big Blue Book. Andy.
This adjustment, what I call an index adjustment, is one of the most basic ones we do many times a day. It's an adjustment that requires no tools (we hope your bike has threaded barrel adjusters) and one that can be reversed as easily as it was changed. The key is to remember which way and how far you turned the barrel. If you can't remember then write it down. Seriously, because even pros will turn the barrel the wrong way sometimes.
So go ahead and try. If you can see the ends of the fixed and the rotating parts of the barrel you can actually see the increased length of the barrel's overall length. After making a barrel change, that is recorded/remembered, pedal the bike to see what result is gained. This process of trial a bit of barrel change then test the bike is far easier to do if the bike can be stationary and the rear wheel off the ground. (A loop of cord around the seat and a ceiling joist, a trainer stand with the resistance off, a repair stand, a friend) so you can pedal and also closely watch the der moving the chain over the rear cogs. The goal is to have the der pulley directly below each cog after each shift has been done. A slight push/pull on the der, when at this balanced cable adjustment, will start to scuff the next larger cog or try to climb off the cog the chain is on. Release the push/pull and the pulley re centers under the intended cog. If this is all done and using the controller (lever) but you can't shift into the lowest gear then your index adjustment is likely one whole cog off. So just reverse what you did. This is why you want to remember what you did, how much of how many barrel turns, so you can go back and try again.
Cable caused ghost shifting usually is a slowly degrading process. Ride by ride the cable/casing system is changing bit by bit and at some point the collective bits are enough to cause a skip due to the pulley no longer being directly under the intended cog. A sensitive rider can often feel this degradation before skipping has started and might only need to turn the barrel less then a full turn to keep up with cable "stretch" (actually casing compression). A rider who wasn't so sensitive or proactive might need to turn the barrel more then a turn, two or more turns suggest an extreme case.
If the skipping came on suddenly, and the rider is sensitive, then there might have been an incident like a fall down of the bike (I've even fixed bikes that were impacted by soccer balls and trash cans) may have happened and the entire rear der might have been bent inward. If this has happened then besides the, now, misalignment between the intended cog and where the bent der places the pulley there's also the chance that the der can now overlap with the spokes when shifted to the large cog. Not good! Most modern bikes have an attachment tab called the hanger that is purposely weaker then the frame, can bend under relatively little pressure and can be either realigned or replaced as needed.
There are other reasons that a bike will ghost shift but with a new bike these other causes that are extreme wear related are not likely to be at play (yet).
The OP said the bike is new. cable settling in is expected on a new bike. This is but one reason that LBSs will offer a free after sale service at no cost, to retune the bike after initial break in periods. If the bike was bought at a shop then I strongly suggest taking the shop up on this offer. Because there's a number of other aspects of safe and sound mechanical function that also are bedding in and should have an experienced hand correct/confirm their condition/tuning/adjustment. If the bike wasn't bought from a LBS, or the shop sucks and doesn't offer after sale service then the single best source for mechanical help is possibly Park's Big Blue Book. Andy.
11-23-17 | 06:52 AM
#6
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Joined: Feb 2004
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From: St Peters, Missouri
Bikes: Catrike 559 I own some others but they don't get ridden very much.
Whenever I encounter a problem that doesn't immediately succumb to normal tuning the first thing that I do is to check to see that all the parts are in the proper order. A slightly tweaked derailleur hanger wouldn't surprise me at all. It's relatively easy to check and no amount of tuning will fix your problem is the hanger is indeed wonky.
If that's not the problem, it's still good to be able to positively eliminate it.
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My greatest fear is all of my kids standing around my coffin and talking about "how sensible" dad was.
11-23-17 | 07:06 AM
#7
Mechanic/Tourist
Joined: Apr 2007
Posts: 7,522
Likes: 12
From: Syracuse, NY
Bikes: 2008 Novara Randonee - love it. Previous bikes:Motobecane Mirage, 1972 Moto Grand Jubilee (my fave), Jackson Rake 16, 1983 C'dale ST500.
This is one case where I definitely would have the hanger checked, as well as double-checking the cables for free movement and the housings for proper length, termination and seating. I would also advise you to check the seller's warranty/guarantee provisions. They may provide an allowance for repair costs for original problems.
11-24-17 | 08:13 AM
#9
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Joined: Jul 2010
Posts: 13,912
Likes: 1,242
From: Montreal Canada
mr goatee, as someone else suggested, check out on youtube the parktools video series. Park Tools make some of teh best bike tools and have an excellent set of a bunch of "how to" vids, well filmed, good sound, clear instructions and a good presenter.
https://www.youtube.com/user/parktoolcompany/featured
take the time looking at some while doing the actual thing in question, and they are a great learning tool.
Kudos to Park Tools making these vids, they really area a great resource and a great help in learning and improving bike mechanic skills, they have been for me. I even looked at one not that long ago when a friend came over to redo his cables and housings and to redo his bar tape. It had been a while since I had retaped a dropbar and as always with something I hadnt done much and or in a long time, I forgot the details, so their vid refreshed the memory and just made for a better job with the new tape.
you'll see the rd adjustment video on the main page I think,
https://www.youtube.com/user/parktoolcompany/featured
take the time looking at some while doing the actual thing in question, and they are a great learning tool.
Kudos to Park Tools making these vids, they really area a great resource and a great help in learning and improving bike mechanic skills, they have been for me. I even looked at one not that long ago when a friend came over to redo his cables and housings and to redo his bar tape. It had been a while since I had retaped a dropbar and as always with something I hadnt done much and or in a long time, I forgot the details, so their vid refreshed the memory and just made for a better job with the new tape.
you'll see the rd adjustment video on the main page I think,
11-24-17 | 08:54 AM
#10
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Joined: Oct 2014
Posts: 14,164
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From: Portland, OR
Bikes: (2) ti TiCycles, 2007 w/ triple and 2011 fixed, 1979 Peter Mooney, ~1983 Trek 420 now fixed and ~1973 Raleigh Carlton Competition gravel grinder
Just got a new Marin four Corners. It has a 50/36/30 in front and 9 speed 11/32 in rear.
I'm having issues on the rear. I shift down (to a larger cog) and oftentimes it drops up a gear (to a smaller cog) This has happened consistently and usually on the larger 4 rear cogs. I will shift to a larger and it will drop back to a smaller. Here's the weird thing. Sometimes after I physically shift, it will on it's on shift back and forth. In other words, I'm pedaling along and it drops to a lower gear, then back up then back down.
It is as if the derailleur is indexing BETWEEN the rear cogs and it can't quite decide which one it is supposed to be on.
So I shifted to the smallest cog, loosened the cable lock nut and pulled the slack out of the cable. Still does it.
So I'm thinking I need to make an adjustment on the rear barrel adjustment. (?)
Do I adjust the barrel to tighten the cable tension or loosen, and does it tighten by turning counterclockwise or clockwise?
I should mention the limit screws seem to be dead on.
I'm having issues on the rear. I shift down (to a larger cog) and oftentimes it drops up a gear (to a smaller cog) This has happened consistently and usually on the larger 4 rear cogs. I will shift to a larger and it will drop back to a smaller. Here's the weird thing. Sometimes after I physically shift, it will on it's on shift back and forth. In other words, I'm pedaling along and it drops to a lower gear, then back up then back down.
It is as if the derailleur is indexing BETWEEN the rear cogs and it can't quite decide which one it is supposed to be on.
So I shifted to the smallest cog, loosened the cable lock nut and pulled the slack out of the cable. Still does it.
So I'm thinking I need to make an adjustment on the rear barrel adjustment. (?)
Do I adjust the barrel to tighten the cable tension or loosen, and does it tighten by turning counterclockwise or clockwise?
I should mention the limit screws seem to be dead on.
And, yes, the rear barrel adjust is the tool to stop this. Backing it out will tighten the cable, speed shifting to bigger cogs and lessen dropping unintended to smaller cogs. (Push the derailleur body toward the wheel to slack the cable whole you turn the barrel. Easier on the threads.)
Ben
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