Gear shifting issues

[Russell]

I’m having trouble with the gears.  Quite often, but not always, the gears skip, refuse to shift, ghost shift and generally cause annoyance.

I’ve had several goes at tweaking them but not been able to get them reliable.

I know I need to get the derailleur hanger alignment checked; I used a piece of string over the chain on the large sprocket and then over the lower jockey wheel and the alignment was not perfect.  This method won’t check the left right alignment either.

So, will a misaligned hanger cause these problems?

If, just suppose the hanger is a bit flexible, will that cause these problems?

The bike is newish and not done that many miles so component wear should not be an issue.  All components are from the same manufacturers groupset.

Thanks

R

[LEE]

Last time I experienced that was sticky cable...just before it snapped.

[Brucey]

just because a bike is fairly new it doesn't mean that the cables are going to be perfect; they are typically installed in a hurry and without adequate lubrication. Provided they work OK when the bike is PDI'd, they won't see any further attention before you get the bike, meaning that it is pot luck whether the cables stay good for weeks, months, or years.

I'd set the hanger alignment correctly if it is wrong, check other stuff (adjustments, B tension settings etc) and check/replace the cables, in that order.

cheers

[Russell]

I'll look at the hanger alignment.  It's either pop down to local shop at the weekend and have it done there or splash £32 on a X-Tools tool.  It sounds as though it may need checking more frequently than I would have thought so maybe I'll splash out on one.

Thanks

[Brucey]

BTW you should check the chain for stiff/bad/cracked links too....

cheers

[Biggsy]

Hanger alignment isn't always easy to judge without a proper gauge as some mechs are designed to hang at a funny-looking angle.  It's unlikely to be wrong with a newish bike that hasn't crashed anyway, I would hope.  Flex should not be an issue for the hanger either.

[Samuel D]

Unless the hanger can be seen by eye to be obviously out of alignment, I doubt it would have a significant effect on shifting performance. That has been my experience anyway. Perfect alignment does reduce the last bit of unnecessary chain noise.

What is “newish”? Has the bicycle been ridden in the rain or stored outside? Are the cable housings made by Shimano? Are they the right length? Are the housings cut square and finished with a file and awl? I’d blame the cables if everything else is correctly adjusted.

I’ve never seen a new bicycle with good cables, by the way; this seems to be a job you have to do yourself if you want it done properly.

You don’t say whether everything else is properly adjusted, though. I’d start there. Follow Shimano’s PDF instructions on si.shimano.com, not some random YouTube video.

[LEE]

Last time I experienced that was sticky cable...just before it snapped.

BTW.. Every time I've replaced gear cables I always wished I'd done it sooner.  They generally deteriorate slowly, so you don't realise the sifting is getting worse.

New cables usually results in a moment of joy when you get back out on the road and everything is a slick as a slick thing again.

[LittleSkink]

Had similar frustrations on our tandem - it has low miles but previous owner wasnt exactly the dotting kind. In order of what I have done . . .

Sprayed everything with GT85 and gave it a good clean - almost no improvement

Amazingly - to me anyhow - swapping the chain made no difference even though the old one was a rusty as you like

Replaced cables with Stainless, new outers and ferrules - solved most of the problems, only cost a few quid doing it myself carefully (not yet found a bike shop who can/will take their time and do it "just so")

Swapping from Revoshift to proper trigger shifters helped a little again, but still have some reluctance in upshifting, ie when cable is relaxing, not being pulled

The rear hanger measured fine but what while checking it did notice was a lot of play in the rear mech - thats next on the hit list but the dearest item by far, and shifting is 98% good now . . .

[Russell]

Had a good old go with this issue over the weekend.  I bought an Xtools gear hanger alingnment tool from Chain Reaction (I read the reviews over the pivot play and wasn't disappointed) and found not to my surprise that the hanger was out of alignment.  The titanium hanger is so soft that it took no effort to re-align.  It is 9mmx2mm at it's waisted middle.

The gears change was better but still not good so I investigated further and found that where the cable passes inder the bottom bracket the shop had used a piece of brake outer (spiral wound) as a guide.  This had either been bent into an angle on installation or taken up the angle under tension.  It was presenting considerable resistance to the gear inner sliding through it.

I changed this to a piece of outer that seemed more flexible and now, on the workstand at least, the gears appear to be working correctly.  There was no opportunity to ride it this weekend.

So, questions:

What does the team think about the cross section of the hanger?
How could the under bottom bracket guide be improved?

[Samuel D]

I don’t like the look of that set-up, because the section of cable housing may bend differently as the cable tension varies with the stroke of the derailleur, thus throwing off the indexing.

I would seek to replace that with an inflexible metal tube (e.g. a suitably cut and reshaped V-brake noodle), so that the shape doesn’t change with cable tension.

Can you replace the whole ensemble with a continuous piece of housing from shifter to derailleur?

What frame is this?

[Torslanda]

My approach would be to put the chain on the middle sprocket at the rear and eyeball the chainline over the sprocketand thru the derailleur cage. It needs to be plumb and central.

Don't rule out replacing the hanger, especially if the derailleur cage is vertical but skewed left or right, they will only put up with a certain amount of twisting.

The cable arrangement appears somewhat Heath Robinson. It's not easy to tell from the pics but I'm guessing there should be some kind of ferrule to fit those loops, the kind used on brake outers in old school drop bar levers. Given those short pices of outer are not anchored it would be almost impossible to guarantee the cable stays evenly tensioned across the range of the gearshift. If I'm right, there's your problem.

If the ferrules I mentioned above fit the loops on the eccentric BB then I might be tempted to use a full run of 5mm outer from the shifter, bypassing the downtube stops and fit inline adjusters. Workmanlike but not beautiful. Alternatively consult the frame maker to see if there is a dedicated fit solution. I can't see if it is feasible to fit a conventional 'shoe' as found on the majority of under bracket routed bikes.

Would be interested to hear the solution suggested...

ETA: Cross posted with Samuel D. He can obviously type faster . . .

[Russell]

I don’t like the look of that set-up, because the section of cable housing may bend differently as the cable tension varies with the stroke of the derailleur, thus throwing off the indexing.

Agreed, hence my question.

I would seek to replace that with an inflexible metal tube (e.g. a suitably cut and reshaped V-brake noodle), so that the shape doesn’t change with cable tension.

Good thought

Can you replace the whole ensemble with a continuous piece of housing from shifter to derailleur?

I would rather not as being a tandem frame.....

What frame is this?

A new titanium tandem frame from a reputable dealer.  The frames are sourced in the Far East (not XACD but the name escapes me for now).

[Torslanda]

If you're inclined a shot of the underside of the BB in plan might help.

[Russell]

As you'll appreciate that will require some logistics so may not be immediate!

BTW, I'm thinking cut down brake noodle and Sugru.

[Torslanda]

As you'll appreciate that will require some logistics so may not be immediate!

BTW, I'm thinking cut down brake noodle and Sugru.

No problem.

May I suggest using a flexible noodle? It still sounds a bit bodgetastic! Which is why I'm suggesting contacting the framebuilder/importer direct as they may have a neater solution...

[Brucey]

a couple of questions

1) what gear system are you using?

2) do the cables feel 'stretchy'?

3) how well do you think the cable is running though each cable run?

cheers

[Russell]

1:  Shimano 105 10s throughout
2:  Not that I have noticed
3:  Apart from the now replaced 'noodle' under the BB they feel OK.

As I said up thread, the tweeks and 'noodle' change at the weekend appeared to offer an improvement while on the workstand (well, workmate and rope stand anyway!) but we have yet to ride it.  I did the test using the drag brake to offer load to the system.

[Russell]

Photos as promised.  The angle the gear cables turn through is 139deg and the guides are 9mm od and approx 7mm id.

[Torslanda]

The stop on the end of a v-brake noodle is 5mm O/D. Obviously you can't fit a conventional 'saddle' under the eccentric shell which is why I'm convinced the should be some fitting that plugs into the loops to guide the cable through its direction change. Have you been in touch with the manufacturer?

[Brucey]

I agree in the normal run of things I'd expect a frame manufacturer to have a better plan than that.  I have fitted guides that are of similar ilk to frames, but of a different size so that they will accept pneumatic tubing as a snug fit.  This works pretty well as a cable guide, but I don't think those fittings are the right size for that.

Re the iffy shifting;  shimano 'road' 10s is the most finicky system IMHO. (Daft question; you do have a matched set of parts, right?  Tiagra 4700 uses a different shift ratio to other 10s stuff...).  On a tandem the amount of stretch you can get in the long cable between the system parts and a length of draggy housing is enough to mean that the gears won't run sweetly; ~1mm out at the mech is plenty enough to cause problems.

  The cable housing run that can cause most trouble is the one at the rear mech. If it is (say) cut short so that the housing has a kink at the cable stop or the mech, it will most likely cause troubles. If the housing near the shifter is bad, it will also cause trouble, but it won't be quite the same.   

If you run out of other ideas, go back and check the housing ends are prepped nicely, and/or try fitting a coated inner, or use different cable lube. 11s cable sets come with a little tail ferrule to fit in the rear mech; this fits most 10s mechs too and it makes the cable run smoother, so fitting one of those wouldn't be a bad idea either.

cheers

[Brucey]

I had an idea; 3/32" bore flexible hydraulic brake hose is a little under 6mm OD, and has a pretty slick liner to it, that won't move.

I reckon a couple of short lengths of that would do the job under your BB. To secure it, I reckon a tapered wind of insulation tape could be used to make it a ram-jam fit. Because the hose is strong and springy, it can be made a very tight fit in the guides and it won't collapse down onto the inner cable.

cheers

[Torslanda]

So we're sitting here suggesting bodges  to make several thousand pounds worth of tandem change gear properly?

Anyone else find this incongruous?

I despair . . .

[Polar Bear]

Those guides under the BB I believe are designed for continuous run outer cables / hydraulic pipes and usually seen with disk brakes.   They look to me entirely unsuitable for exposed cabling in the manner that you have it.

Has somebody ballsed up the frame spec?         

[Polar Bear]

Oh, and as a bodge, perhaps a very short section of outer held in place with some sugru or similar.