Tech Ghost shifting...driving me nuts!

Karl

Maximum Pace
Feb 7, 2011
315
135
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Yokohama
#1
Sorry if this is a repeated theme. Searched the forums and didn't find anything... so please indulge me if this has been done.

I have a Felt-Speed 22 cross bike. It is getting a bit old, but it is a trusty steed... or has been till recently. The insurmountable problem is 'ghost shifting'.

Relevant info...

symptoms... ghost shifting only when on small front chain ring. Large ring, no problem.
shifts OK on the inner cassette rings but in on the 4th and 5th ring, never settles in, then on 2 outer rings settles in again.

To date, I've....

replaced the small ring on my compact double, replaced chain at same time.
replaced the derailleur hanger
replaced the rear derailleur
adjusted it myself, and in case of operator headspace error, took to bike shop and they adjusted it too.

problem persists

I'm kind of running out of options. No crashes so no bent frame. I'd work with it, except on a double, I need those gears. Besides, not fun when bike decides to shift at a bad time.... balance being what it is.

Sooooo... any suggestions?


PS. I'm not a particularly active member here but I lurk and read your ride reports carefully. Whether you know it or not, you've saved me from taking some particularly bad routes in favor of much better ones, plus, I've scarfed up the pleasant little shortcuts through the countryside that avoid the worst of the traffic. So... to those who post this ride info... many thanks.
 
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George5

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Oct 16, 2014
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#4
What prompted the change of just the inner chainring?
Why did you replace the hanger and deraiiler if there wasn't a crash? Why didn't you replace the rear cluster at the same time? Not asking out of a sense of "duh" but just to get the pre change condition

I think you have too much slack in the chain and with slightly worn sprockets ( are they?) in the middle of your cluster they are skipping without the tension provided by the large chainset. OR check your B screw, if the rear cluster is fairly new that most likely will be your problem. Where are you located and perhaps we can suggest another mechanic to go to.
 
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Karl

Maximum Pace
Feb 7, 2011
315
135
63
Yokohama
#7
I'm out at Aobadai. The mech at the Coggey shop is not too bad, far as I can tell. Knows his stuff.

I replaced the inner ring about a year ago because it was worn out and skipping. Replaced the rear cassette and chain at the same time.

I replaced the hanger because I had another at hand and wanted to see if the swap out would solve the problem. It didn't.

Have checked the chain for wear. Nada.

Haven't yet replaced the cable and inner housing. I'll give that a try.

I've swapped out my 1 year old cassette with my older one. Get the same shifting pattern in the same two rings on the rear cassette.

Soo.... I'm thinking I'll bite the bullet and try a new chain and rear cassette swap if replacing the inner cable and housing doesn't resolve it.

I'll get back with you all ... Thanks for your help.

If it doesn't fix it... anyone want to buy a bike? (just kidding)
 

George5

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Oct 16, 2014
385
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#8
I doubt replacing the cables will do anything as it isn't ghost shifting on the big chainring. check your chain length and the B screw. You might want to try another mechanic straight away as you aren't saving yourself any money by randomly replacing parts and another guy might look at the problem from another prospective. Tell the mechanic what you have done thus far. goodluck. there are a heap of bike shops in Aoba ku and Yokohama.
 

Karl

Maximum Pace
Feb 7, 2011
315
135
63
Yokohama
#9
Thanks to all for the help.

It is a pretty annoying problem and I'd like to tackle it from the pt of view of logic, vs brute force (replacing parts and hoping for the best). The fact that the ghost shifting happens at exactly the same place on two different cassettes, and it is exactly the gearing I use most often, has me favoring the 'wear' theory, although visually, those gears on the cassettes don't look any more worn than the others. I've rechecked the B-screw settings and chain length. Good to go. Checked chain wear, still at .5.

One final idea... my shifters are old as well. Could it be that the indexing is somehow screwed up? Ever heard of such a thing?

You're probably right (George5), I guess it's time to try to find another mechanic who is willing to work through this with me.

Again... thanks for all the ideas. Hope to have it resolved by Friday so I can take it up in the mountains on the weekend.
 

D'Pioneer

Far beyond the black horizon
Oct 9, 2015
458
229
83
#10
You're probably right (George5), I guess it's time to try to find another mechanic who is willing to work through this with me.
No, do it yourself. Fixing bikes is easy and just a process of elimination. You have already demonstrated that you are more than qualified to do this, so carry on the quest for the truth yourself.

I'd like to tackle it from the pt of view of logic
Great, so let's concisely evaluate the current state of play and work out the next logical steps.

So far you have ruled out;

-Chain wear
-Mech angle (via hanger bending etc)
-Mech itself
-Small ring on the chainset
-Shifting indexing
-B Screw
-Chain length

Next steps;

-Take the rear wheel off, so the rear mech is sitting in mid air and the chain is loose, then click up and down the gears all the way. Pay very close attention to any stiffness or shifting issues at all points. As you have a new rear mech, this will indicate an issue elsewhere in the system which can then be addressed (cables, or shifters)
-Swap the cassette (putting the logical process to one side for a second, I reckon it is this; cassettes wear out just like any other part)

Try those, then get back to us.

Technical notes;

-Shifting problems will always become more apparent when in the smaller ring on the front of the bike, due to the rear mech cage being less tensioned (pulled forward). A tensioned mech cage will 'iron out' or mask shifting problems. When in the small ring, the mech is at a relatively lower tension and relaxed position, so irregularities can be easily felt. This is why, for example, you always adjust the B-screw when in the small ring on the front.
-Teeth dont need to look worn to actually be worn.
 

Karl

Maximum Pace
Feb 7, 2011
315
135
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Yokohama
#11
Thanks for the ideas. I really like working on my bikes and keeping them in top shape. I figure I'm not too bad at it anymore, but this problem has defied all my efforts. I'll definitely give your ideas a try before raising the white flag and searching for a better mechanic. I've got lots of miles on both my cassettes now, and even though they don't look worn, maybe it's time to replace them anyway.

Anyway... I'll give your ideas a try and let you know. Thanks again.
 

leicaman

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Sep 20, 2012
2,535
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Asakadai, Saitama
#12
Ah, I thought you had replaced your cassette with a new one and it was still doing it. If I were you, new cassette, then new cables+housing (probably a good idea to do this anyway if you haven't done it for a while). If that doesn't fix it, just buy @saibot 's crazy value bike and never look back ;)
 
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D'Pioneer

Far beyond the black horizon
Oct 9, 2015
458
229
83
#15
Well then, is the scary lady making the chain shift up or down to the next cog on the cassette without touching the shifters, or she haunting the chain so it slips off the teeth on the same cog and jolts forward, as if possessed, with the pedal stroke?
 
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Karl

Maximum Pace
Feb 7, 2011
315
135
63
Yokohama
#16
It kinda works like this. Smooth shifting from the big gear on rear cassette thru the next 4. Then on smaller gears 5 and 6, it doesn't seat properly on the gears. Seems to have a mind of its own and wanders back and forth. Just weird....possessed? Then back to normal on two outer gears.

Should I consider a bike exorcism?
 

D'Pioneer

Far beyond the black horizon
Oct 9, 2015
458
229
83
#17
Please confirm the following;

-there are 8 cogs on the cassette
-cogs 5 and 6 are the issue
-no other cogs have a problem
-the chain jumps between cogs 5 and 6 when pedalling

More specific questions;

-When you are in cog 5, does the chain jump to cog 6?
-when you are in cog 6, does the chain jump to cog 5?
-is the problem any different in its severity when shifting down into the 5 - 6 range from cogs 1,2,3,4, than is it when shifting up into to 5 - 6 from cogs 7 and 8?
 

Karl

Maximum Pace
Feb 7, 2011
315
135
63
Yokohama
#18
Uhh... good questions. Can't say that I've been that careful to notice exactly how it jumps. It'll have to wait till Friday before I can have time to check it out more carefully, though.

For now though, it is a 9-speed. Best as I can remember, what happens is that shifting from cog 5 to 6, it rides on the top of the next cog and, at its worst, skips 6 altogether. Seats on 7 then OK for 8 and 9. If I'm starting from dead stop and I'm on cogs 6 or 7, it often skips around as well and under strain of starting off, it is pretty unreliable. I stay on my larger front ring much more so I can use the bike w/o the problem, but not a good solution.

Anyway... it'll have to wait till Friday when I have time to work/play with it.

Thanks for the good questions.
 

D'Pioneer

Far beyond the black horizon
Oct 9, 2015
458
229
83
#19
I suspect this is a cable/shifter setup or wear issue. The problems you are having are indexing based and as you have replaced the rear mech and hanger it can't be that

Do the steps I told you including shifting up and down with the rear wheel off and post results here.

We'll get this sorted for you.
 
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