Koyote

I've had this problem with a road bike for a few years, and have asked a couple mechanics to look into - usually when the bike is in a shop for other work. So far, no one has solved it.

Ten-year old Shimano 10-speed groupset with compact crankset. Bike shifts fine on the top 6-7 cogs (biggest cogs/lowest gears). When I try to shift down the cassette past the sixth or seventh cog (so, trying to shift to higher gears), chain won't drop down to next cog immediately, if at all -- usually I have to click the shifter again, and then the chain will drop two cogs. Shifting up the cassette (to smaller gears) works fine.

Following has been tried:
-Derailleur hanger alignment checked (3-4 times).
-New cable.
-New chain (replaced regularly anyway).
-New cassette (normal replacement)
-New RD.

I've even tried a different wheelset. Nothing works.

Ideas from the BF brain trust?

Thanks in advance!

Elvo

New shifter

Bill Kapaun

To me, that's a classic case of too much cable friction.
Did you replace the housing too?

noglider 

Spray lubricant into the shifter every day for several days.

Koyote

Tried it. No effect.

HTupolev

Is the derailleur possibly getting gunked up with anything that would weaken the action of the return spring?

Does the chainring you're in impact whether the problem occurs?

What's the chain gap like? Is the distance between the rear derailleur's jockey pulley and the spot where the chain contacts the cassette cog reasonable - and not excessively large - in all gears?

Koyote

That occurred to me, but the problem started when the Ultegra shifter had <10k miles. Do they really crap out that young?

Koyote

RD is clean. Problem occurs on both chainrings. Chain gap (chain length) is good.

Koyote

Good idea, and cheap.

Elvo

Ultegra 6800 is known to chew up cables at the shifter and have some of the strands get stuck in the mechanism.

Koyote

Not just Ultegra! My fairly new bike has 11sp 105, and did that to the RD cable at only 4,000 miles. First time I've had a cable fail (usually they just get replaced for old age), and first time I'd heard of that happening -- but the mechanic said it's not uncommon.

BUT, the Ultegra shifter has never had a cable failure. The cables have only been replaced for normal wear and tear, and to try to solve this problem. Still think it could be a bad shifter?

HTupolev

Chain gap can be affected by chain length, but it's not purely a matter of chain length. It's heavily controlled by the rear derailleur's b-screw as well, and by the geometry of the derailleur and the shape of the cassette.

Not necessarily, but things can happen to them.

Have you tried lubing the shifter by hitting it with a bit of oil lubricant? If that doesn't do anything, you could also try blasting it with spray degreaser and then re-lubing.

Spoonrobot 

Bike mechanics often suffer from a lack of diagnostic tools. I have a set of 9/10/11 speed downtube shifters mounted on handlebar clamps so I can test situations like yours to rule out the shifter itself being the issue. If you can't find a mechanic that has a set it may be worth your while to buy even just a cheap set of friction shifters to test for yourself.

Replacing cables without doing the housing is being exceeding frugal for no reason. The two should almost always be done together.

I've solved the same issue several times with unusual culprits being:

• dropouts out of alignment (side to side as well as forward to rear)
• dropout faces not on the same plane
• rear triangle out of alignment (due to crash that happened outside of owner's knowledge)
• derailleur hanger twisted (don't just check up/down)
• broken ratchet tooth inside shifter

rccardr 

Koyote

Thanks for all of the advice and suggestions, everyone!

I have one more event to ride this year, then will take it to a shop since cable and housing replacement is beyond my abilities. Will start there and see if it solves the problem, and/or whether the mechanic has any other ideas. Will post back here in a couple months, hopefully.

Speedway2

One of my bikes started doing what I call "ghost shifting"(after many months hanging from the rafters). Similar to what you're experiencing.

Since it wasn't my primary bike I didn't need to fix it right away. I ended up replacing the front and rear gear cables/housings, cleaned and lubed the shifters...voila problems solved!

Might have been a situation of dried lube in the shifters and gummed up cables.....

GZano

I had a similar situation. Thought it might be the cable but it was not. It ended up simply being the cable housing. I guess they must ware a bit internally. Had about 20K miles on the housings.

andrewclaus

If the bike has external cables with slotted stops, it's easy enough to try components one at a time. With bike in stand, shift into low, stop pedaling, shift into high, then you can pull one housing out of a stop.

Pull all housings out and inspect for friction and kinks, especially the rear loop.

Work shifter while pulling lightly on the cable to feel the shifter action.

Push cable end out of shifter to inspect for fraying.

With shifter in high, reinstall housings, then shift manually by pulling the cable away from the frame at the down tube or top tube. See if you can recreate the problem with the shifter out of the circuit.

jimincalif

mtbikerinpa

Easy diagnostic, disconnect the cable from the derailleur. If you can finger the unit and it springs back through the offending gears then it is not that. If it still is hesitant than it could be the spring in the derailleur or lube. I just went through that with my commuter and it was a bur in the cable housing up at the base of the shifting lever but it wasn't apparent til i went up one segment at a time. if that doesn't change it, then I would go shifter.

79pmooney

My first thought.

A simple test - throw the bike on a stand. Undo the cable clamp on the rear derailleur. Now pedal the bike and push the derailleur to shift into the biggest cog. Ease off on the derailleur to shift one cog at a time. Does the shifting hang up as before when you get to cogs 6 and 7? If yes, the cableisn't your issue,

If the derailleur now shifts smoothly, time for detective work. Something somewhere is interfering with the slide of the cable. A possible way of finding the issue would be to take this now dis-connected cable and pull on it as you shift. You should be able to feel the same issue the derailleur is seeing. If yes, pull the cable out of the housing between the chainstay and the derailleur. Repeat. The issue still there? Keep pulling the next segment of cable out of the next housing or guide. When the cable finally runs free at every shift you know you just went past the issue. Look for something interfering whit the cable. It may be a bend the cable must make as it goes into or out of a cable housing. It may be a wire of the housing hitting the cable. (A housing that has been cut with most cable cutters will need the cut cleaned up to avoid just that, Many of us fill the metal smooth. Many of us routinely push a sharpened spoke into the housing to bend back offenders. I often do both, Always look. Those sharpened spokes, with one end bent to a nice handle are in every Portland mechanic's toolbox and is called here "pokey tools". They have lots of other uses, but this alone justifies their existence.)

If you get all the way to the shifter and don't find anything, ie the probem is still there, then it is time to diagnose the shifter itself. But I'm betting you will have already found the problem - unless the issue is how the cable (and housing) come off the shifter itself. You may have to unwrap your bar tape and look I had you go through all of the above first because it all goes fast, is easy and doesn't require replacing anything unless it is bad. And if the issue is under the tape or in the shifter, you are redoing all the first anyway.

Now, if the derailleur flunks the first test, then you know it is the issue. Skip the rest. Has the derailleur been damaged? (Bike falling over, crash?) Is the pivot and parallelogram hinges lubed? When you push the the body in like you did at the beginning of the test, do you feel any resistance that isn't the spring? Cable and housing run clean into the derailleur body?

A lot to look at, But I am 99% sure you will find the issue. (And maybe you can see why I still love those oh-so-simple downtube shifters. One small cable bend at the bottom bracket. One cable housing at the rear derailleur. Nothing out of sight. And those shifters - some of the simplest, most reliable things man has invented.)

Ben

daoswald

I had a similar issue that was driving me nuts, and that eluded mechanics as well.

It turned out that there was sand in my right shifter (Shimano 105). "The incident" occurred ten years ago when I went off the MUP near Santa Monica, CA, and ended up brifter-down into the beach. I cleaned it up at the time, or so I thought, and it worked great for many years. Suddenly this year things started getting bad. But the symptoms were hard to trace back to the shifter. Finally I cleaned it out with WD40 while the bike was hanging nose-down. About ten pounds of sand came out of the shifter from places I didn't even know existed. It was like watching Michael Carbonara pull sixteen hamburgers out of a small bag. Then it was fine, for about a week when the problem returned. So I hung the bike nose-down again and this time spent about an hour blowing the shifter out with compressed air. This time I created a sandstorm the likes of which the Sahara has never seen. After I dug my vehicles out of the sand drifts and unburied my shoes I took the bike for a spin and the shifting was flawless.

Ok, in seriousness, there was probably about a thumble-full of sand that came out over the course of several cleanings, alternating between WD40 and the compressed air. But I'm convinced it only took one or two poorly placed grains to cause the shifting to be bad.

Clean out your shifter. If necessary, remove it from the bike and clean it even better.

I also discovered my chain was longer than necessary, resulting in a tension imbalance that required I trim down on the b-screw more than was necessary once I moved to a slightly shorter chain. This also improved my shift quality a little.

Shimagnolo

The symptoms described sound exactly what I've had every time an RD shift cable starts fraying inside the shifter.
The last time it happened, there was an interesting twist:
On threading the new cable through the last segment of housing (between chainstay and RD), it felt very tight;
So I pulled it back out of the housing, and found a single loose strand of cable was still inside the housing.
That is the first time I've found broken strands outside of the shifter.

Zef

Did the shop check rear derailleur alignment at the 3 and 9 o'clock positions as well as at 12 and 6 o'clock positions? it could be your hanger is out of alignment in the horizontal plane but not the vertical plane.

It could also be that the housing loop from your chainstay to the rear derailleur is not large enough in diameter (read: use a longer length of housing). I had a similar issue with a campy record 10 speed rear derailleur and did a bunch of reading/research and found that the traditional size loop needed to be enlarged as the smaller loop diameter caused enough friction to muck up shifting.

-J

velorider562

If the shifting gets worse between the higher vs lower gears, then it might be the lower limit screw. The cable tension ensures the derailleur moves a fixed amount, but if the starting point is not correct by the time the derailleur gets to the larger cogs the derailleur is off by a small amount. Try unscrewing the lower limit screw a half turn and see what the impact is.

The lower limit screw is frequently neglected but is critical for precise shifts.