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Ghost Shifting



 
 
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  #1  
Old October 2nd 18, 07:10 PM posted to rec.bicycles.tech
JBeattie
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Posts: 5,870
Default Ghost Shifting

O.K., reality check. I was riding in with my son this morning, and he had a sudden attack of ghost shifting or skipping of some sort. I was watching his rear wheel (my usual position, hunkered down behind him), and I didn't see chain skip.

IME, ghost shifting usually happens with a sticky cable at the BB, but what is the likelihood that this is a casette/chain issue? I changed the chain but not the cassette a month ago. It worked beautifully -- no skipping, but I'm wondering if you can hit a tipping point where the cassette goes and the chain is O.K., and you get shift issues. If the cassette is too worn, I usually get problems the moment I put on a new chain and not later.

-- Jay Beattie.
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  #2  
Old October 2nd 18, 07:17 PM posted to rec.bicycles.tech
[email protected]
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Posts: 1,261
Default Ghost Shifting

On Tuesday, October 2, 2018 at 11:10:59 AM UTC-7, jbeattie wrote:
O.K., reality check. I was riding in with my son this morning, and he had a sudden attack of ghost shifting or skipping of some sort. I was watching his rear wheel (my usual position, hunkered down behind him), and I didn't see chain skip.

IME, ghost shifting usually happens with a sticky cable at the BB, but what is the likelihood that this is a casette/chain issue? I changed the chain but not the cassette a month ago. It worked beautifully -- no skipping, but I'm wondering if you can hit a tipping point where the cassette goes and the chain is O.K., and you get shift issues. If the cassette is too worn, I usually get problems the moment I put on a new chain and not later.

-- Jay Beattie.


This isn't uncommon with Campy gear. You have to have, A. Perfect alignment of the rear derailleur on the cassette and B. The shifting ratchet cannot be overly worn.

The Japanese stuff usually doesn't have this problem. I don't remember pulling these things apart but while they are somewhat sensitive to misalignment I haven't seen a worn ratchet causing problems.

The rear derailleur has such spring pressure that I can't see sufficient drag from the bottom bracket wire guide causing any troubles.
  #3  
Old October 2nd 18, 09:44 PM posted to rec.bicycles.tech
AMuzi
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Posts: 13,447
Default Ghost Shifting

On 10/2/2018 1:10 PM, jbeattie wrote:
O.K., reality check. I was riding in with my son this morning, and he had a sudden attack of ghost shifting or skipping of some sort. I was watching his rear wheel (my usual position, hunkered down behind him), and I didn't see chain skip.

IME, ghost shifting usually happens with a sticky cable at the BB, but what is the likelihood that this is a casette/chain issue? I changed the chain but not the cassette a month ago. It worked beautifully -- no skipping, but I'm wondering if you can hit a tipping point where the cassette goes and the chain is O.K., and you get shift issues. If the cassette is too worn, I usually get problems the moment I put on a new chain and not later.

-- Jay Beattie.


Right, worn teeth is a different symptom from changing gears
randomly. See if the rim rocks side to side(bearing
problem) or if the cassette rocks on the body (CS lockring
problem). Also loose QR does that and odd noises.

Those are the most common things. Beyond those it's harder
to track; yes, cable troubles, split casing or ferrule,
internal shifter problem and so on.

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971


  #4  
Old October 3rd 18, 04:14 AM posted to rec.bicycles.tech
Frank Krygowski[_4_]
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Posts: 10,538
Default Ghost Shifting

On 10/2/2018 2:10 PM, jbeattie wrote:
O.K., reality check. I was riding in with my son this morning, and he had a sudden attack of ghost shifting or skipping of some sort. I was watching his rear wheel (my usual position, hunkered down behind him), and I didn't see chain skip.

IME, ghost shifting usually happens with a sticky cable at the BB, but what is the likelihood that this is a casette/chain issue? I changed the chain but not the cassette a month ago. It worked beautifully -- no skipping, but I'm wondering if you can hit a tipping point where the cassette goes and the chain is O.K., and you get shift issues. If the cassette is too worn, I usually get problems the moment I put on a new chain and not later.


I guess I don't understand. To me, "ghost shifting" always meant the
bike tries to at least partially shift to a different rear cog. My
folding bike does that sometimes until the cables settle in after being
folded for a while. If I look down, I can usually see the unbidden
attempt at a shift.

Did you see his chain move laterally? If not, I wouldn't call it ghost
shifting.

When I've put a new chain on a too-old cog and gotten chain skip, it's
always occurred only under heavy pedal pressure; and while it's probably
visible from the rear, I've never been able to actually see it happen.


--
- Frank Krygowski
  #6  
Old October 3rd 18, 05:04 PM posted to rec.bicycles.tech
JBeattie
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Posts: 5,870
Default Ghost Shifting

On Tuesday, October 2, 2018 at 8:14:46 PM UTC-7, Frank Krygowski wrote:
On 10/2/2018 2:10 PM, jbeattie wrote:
O.K., reality check. I was riding in with my son this morning, and he had a sudden attack of ghost shifting or skipping of some sort. I was watching his rear wheel (my usual position, hunkered down behind him), and I didn't see chain skip.

IME, ghost shifting usually happens with a sticky cable at the BB, but what is the likelihood that this is a casette/chain issue? I changed the chain but not the cassette a month ago. It worked beautifully -- no skipping, but I'm wondering if you can hit a tipping point where the cassette goes and the chain is O.K., and you get shift issues. If the cassette is too worn, I usually get problems the moment I put on a new chain and not later.


I guess I don't understand. To me, "ghost shifting" always meant the
bike tries to at least partially shift to a different rear cog. My
folding bike does that sometimes until the cables settle in after being
folded for a while. If I look down, I can usually see the unbidden
attempt at a shift.

Did you see his chain move laterally? If not, I wouldn't call it ghost
shifting.

When I've put a new chain on a too-old cog and gotten chain skip, it's
always occurred only under heavy pedal pressure; and while it's probably
visible from the rear, I've never been able to actually see it happen.


I was watching it this morning, and it isn't ghost shifting. It is skipping in 11/12. The chain is not moving laterally -- its just jumping on the cog. He's going to check derailleur tension at work (they have a shop there). The cassette is tight, and the only other explanation, IMO, would be worn cogs.

This is the Roubaix that was stolen and found by Bike Index and PPB. https://bikeindex.org/news/bike-inde...018-recoveries (the post with the mug shot -- the thief actually has a nice haricut). It had fairly low mileage and an OE cassette. I put a new 11sp chain on it when I rebuilt it because someone had side loaded the existing chain and popped a link or somehow popped a link. They also banged up the chain ring. When I installed the new chain, it shifted beautifully and still shifts beautifully on the stand. I checked it this morning. It may be the case that the cassette had more mileage on it than I recalled.

-- Jay Beattie.
  #7  
Old October 3rd 18, 05:27 PM posted to rec.bicycles.tech
Frank Krygowski[_4_]
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Posts: 10,538
Default Ghost Shifting

On 10/3/2018 12:04 PM, jbeattie wrote:
On Tuesday, October 2, 2018 at 8:14:46 PM UTC-7, Frank Krygowski wrote:
On 10/2/2018 2:10 PM, jbeattie wrote:
O.K., reality check. I was riding in with my son this morning, and he had a sudden attack of ghost shifting or skipping of some sort. I was watching his rear wheel (my usual position, hunkered down behind him), and I didn't see chain skip.

IME, ghost shifting usually happens with a sticky cable at the BB, but what is the likelihood that this is a casette/chain issue? I changed the chain but not the cassette a month ago. It worked beautifully -- no skipping, but I'm wondering if you can hit a tipping point where the cassette goes and the chain is O.K., and you get shift issues. If the cassette is too worn, I usually get problems the moment I put on a new chain and not later.


I guess I don't understand. To me, "ghost shifting" always meant the
bike tries to at least partially shift to a different rear cog. My
folding bike does that sometimes until the cables settle in after being
folded for a while. If I look down, I can usually see the unbidden
attempt at a shift.

Did you see his chain move laterally? If not, I wouldn't call it ghost
shifting.

When I've put a new chain on a too-old cog and gotten chain skip, it's
always occurred only under heavy pedal pressure; and while it's probably
visible from the rear, I've never been able to actually see it happen.


I was watching it this morning, and it isn't ghost shifting. It is skipping in 11/12. The chain is not moving laterally -- its just jumping on the cog. He's going to check derailleur tension at work (they have a shop there). The cassette is tight, and the only other explanation, IMO, would be worn cogs.


I'm betting on the worn cogs.

Someone (I forget who) sells a tool to test cogs for wear. It's like a
modified chain whip. You use its handle to apply lots of tension to its
short strand of chain and check whether the 3rd or 4th link still seats
smoothly on the cog teeth. I borrowed one once, then made my own by
modifying an extra chain whip.

But it's not infallible. And IME, when a cog is marginal the chain skips
can be frustratingly intermittent.


--
- Frank Krygowski
  #8  
Old October 3rd 18, 05:40 PM posted to rec.bicycles.tech
[email protected]
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Posts: 1,261
Default Ghost Shifting

On Wednesday, October 3, 2018 at 9:04:10 AM UTC-7, jbeattie wrote:
On Tuesday, October 2, 2018 at 8:14:46 PM UTC-7, Frank Krygowski wrote:
On 10/2/2018 2:10 PM, jbeattie wrote:
O.K., reality check. I was riding in with my son this morning, and he had a sudden attack of ghost shifting or skipping of some sort. I was watching his rear wheel (my usual position, hunkered down behind him), and I didn't see chain skip.

IME, ghost shifting usually happens with a sticky cable at the BB, but what is the likelihood that this is a casette/chain issue? I changed the chain but not the cassette a month ago. It worked beautifully -- no skipping, but I'm wondering if you can hit a tipping point where the cassette goes and the chain is O.K., and you get shift issues. If the cassette is too worn, I usually get problems the moment I put on a new chain and not later.


I guess I don't understand. To me, "ghost shifting" always meant the
bike tries to at least partially shift to a different rear cog. My
folding bike does that sometimes until the cables settle in after being
folded for a while. If I look down, I can usually see the unbidden
attempt at a shift.

Did you see his chain move laterally? If not, I wouldn't call it ghost
shifting.

When I've put a new chain on a too-old cog and gotten chain skip, it's
always occurred only under heavy pedal pressure; and while it's probably
visible from the rear, I've never been able to actually see it happen.


I was watching it this morning, and it isn't ghost shifting. It is skipping in 11/12. The chain is not moving laterally -- its just jumping on the cog. He's going to check derailleur tension at work (they have a shop there). The cassette is tight, and the only other explanation, IMO, would be worn cogs.

This is the Roubaix that was stolen and found by Bike Index and PPB. https://bikeindex.org/news/bike-inde...018-recoveries (the post with the mug shot -- the thief actually has a nice haricut). It had fairly low mileage and an OE cassette. I put a new 11sp chain on it when I rebuilt it because someone had side loaded the existing chain and popped a link or somehow popped a link. They also banged up the chain ring. When I installed the new chain, it shifted beautifully and still shifts beautifully on the stand. I checked it this morning. It may be the case that the cassette had more mileage on it than I recalled.

-- Jay Beattie.


This "jumping" is an attempt to shift. You have a very slight misalignment and the chain is catching the lift grooves on the cassette. If it is doing that while you are in the 11 simply take about 1/8th of a turn counterclockwise on the rear derailleur adjustment. NO MORE.

When you are close to correct the amount of misalignment that causes this is very small and you have to be careful that only slight adjustments are made to it.
  #9  
Old October 4th 18, 06:29 PM posted to rec.bicycles.tech
Mark J.
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Posts: 840
Default Ghost Shifting

On 10/3/2018 9:04 AM, jbeattie wrote:
On Tuesday, October 2, 2018 at 8:14:46 PM UTC-7, Frank Krygowski wrote:
On 10/2/2018 2:10 PM, jbeattie wrote:
O.K., reality check. I was riding in with my son this morning, and he had a sudden attack of ghost shifting or skipping of some sort. I was watching his rear wheel (my usual position, hunkered down behind him), and I didn't see chain skip.

IME, ghost shifting usually happens with a sticky cable at the BB, but what is the likelihood that this is a casette/chain issue? I changed the chain but not the cassette a month ago. It worked beautifully -- no skipping, but I'm wondering if you can hit a tipping point where the cassette goes and the chain is O.K., and you get shift issues. If the cassette is too worn, I usually get problems the moment I put on a new chain and not later.


I guess I don't understand. To me, "ghost shifting" always meant the
bike tries to at least partially shift to a different rear cog. My
folding bike does that sometimes until the cables settle in after being
folded for a while. If I look down, I can usually see the unbidden
attempt at a shift.

Did you see his chain move laterally? If not, I wouldn't call it ghost
shifting.

When I've put a new chain on a too-old cog and gotten chain skip, it's
always occurred only under heavy pedal pressure; and while it's probably
visible from the rear, I've never been able to actually see it happen.


I was watching it this morning, and it isn't ghost shifting. It is skipping in 11/12. The chain is not moving laterally -- its just jumping on the cog. He's going to check derailleur tension at work (they have a shop there). The cassette is tight, and the only other explanation, IMO, would be worn cogs.

This is the Roubaix that was stolen and found by Bike Index and PPB. https://bikeindex.org/news/bike-inde...018-recoveries (the post with the mug shot -- the thief actually has a nice haricut). It had fairly low mileage and an OE cassette. I put a new 11sp chain on it when I rebuilt it because someone had side loaded the existing chain and popped a link or somehow popped a link. They also banged up the chain ring. When I installed the new chain, it shifted beautifully and still shifts beautifully on the stand. I checked it this morning. It may be the case that the cassette had more mileage on it than I recalled.

-- Jay Beattie.


Don't rule out munged cogs, perhaps bent by whatever damaged the chain
while the bad guy had the bike. Who knows what bizarre treatment the
bike was subjected to?

Mark J.


  #10  
Old October 4th 18, 08:12 PM posted to rec.bicycles.tech
Duane[_2_]
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Posts: 401
Default Ghost Shifting

On 04/10/2018 1:29 PM, Mark J. wrote:
On 10/3/2018 9:04 AM, jbeattie wrote:
On Tuesday, October 2, 2018 at 8:14:46 PM UTC-7, Frank Krygowski wrote:
On 10/2/2018 2:10 PM, jbeattie wrote:
O.K., reality check.Â* I was riding in with my son this morning, and
he had a sudden attack of ghost shifting or skipping of some sort.
I was watching his rear wheel (my usual position, hunkered down
behind him), and I didn't see chain skip.

IME, ghost shifting usually happens with a sticky cable at the BB,
but what is the likelihood that this is a casette/chain issue?Â* I
changed the chain but not the cassette a month ago.Â* It worked
beautifully -- no skipping, but I'm wondering if you can hit a
tipping point where the cassette goes and the chain is O.K., and you
get shift issues. If the cassette is too worn, I usually get
problems the moment I put on a new chain and not later.

I guess I don't understand. To me, "ghost shifting" always meant the
bike tries to at least partially shift to a different rear cog. My
folding bike does that sometimes until the cables settle in after being
folded for a while. If I look down, I can usually see the unbidden
attempt at a shift.

Did you see his chain move laterally? If not, I wouldn't call it ghost
shifting.

When I've put a new chain on a too-old cog and gotten chain skip, it's
always occurred only under heavy pedal pressure; and while it's probably
visible from the rear, I've never been able to actually see it happen.


I was watching it this morning, and it isn't ghost shifting.Â* It is
skipping in 11/12. The chain is not moving laterally -- its just
jumping on the cog. He's going to check derailleur tension at work
(they have a shop there).Â* The cassette is tight, and the only other
explanation, IMO, would be worn cogs.

This is the Roubaix that was stolen and found by Bike Index and PPB.
https://bikeindex.org/news/bike-inde...018-recoveries (the
post with the mug shot -- the thief actually has a nice haricut).Â* It
had fairly low mileage and an OE cassette.Â* I put a new 11sp chain on
it when I rebuilt it because someone had side loaded the existing
chain and popped a link or somehow popped a link. They also banged up
the chain ring.Â*Â* When I installed the new chain, it shifted
beautifully and still shifts beautifully on the stand. I checked it
this morning. It may be the case that the cassette had more mileage on
it than I recalled.

-- Jay Beattie.


Don't rule out munged cogs, perhaps bent by whatever damaged the chain
while the bad guy had the bike.Â* Who knows what bizarre treatment the
bike was subjected to?

Mark J.



In my experience what often happens is that you let the chain go too
long and when you change the chain the cassettes are worn enough to
cause slip on the new chain.
 




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