Damn Shifting!

[Ajax Bay]

Agree - entirely required, but ending up off the cassette has nothing to do with indexing - that's the point I was making (note that the OP makes no suggestion about chain " end[ing] up in the spokes or drop[ping] off the smallest [sprocket]").
His is a combo of indexing and making sure the ferrules are all firmly where they ought to be. All he's done is change the cable. There should be zero need to touch the H/L limit screws.

 

[keithmac]

Fill your boots.

 

[Lovacott]

Limit screws limit. They have no effect on indexing. The start point for correct indexing is actually the second smallest sprocket. Get that right and . . . happy days. Set the limit screws (with the cable still in tension) so the chain can drop onto the smallest sprocket (but not further) and so the chain can climb onto the largest sprocket (but not come off towards the spokes).
HTH

I open up my limit screws prior to indexing and then set them once I'm happy with the shifting. This prevents me from confusing limit stops with cable tension settings. I set the front limit afterwards by tightening the screws until the mech rubs the chain and then back off a quarter turn or so. The rear mech I set by tightening until I hear noise and then backing off until the noise goes.

The first time I indexed the front, I set the large ring limit a tad too tight before indexing and I ended up over tensioning the cable trying to force the mech over the the large ring making it hard to get my grip shifter to click into the 3 position. Setting the limits after indexing prevents this.

I also try to make sure I have a couple of turns left over in either direction on both barrel adjusters so that future adjustments can be done using just those. Generally, a quarter turn either way is all that is needed for a fine tune.

Not sure if it matters, but when I park up the bike, I don't leave it in gears which keep the cables fully tensioned?

Shimano provide very good online dealers manuals for their components which walk you through the full installation procedure and if followed to the letter, leave your indexing faultless. I'm fitting a new front mech this weekend and it has big ring spacing guide and a removable alignment block to aid installation. I'm quite looking forward to doing the job.

 

[Ajax Bay]

I open up my limit screws prior to indexing and then set them once I'm happy with the shifting.
Shimano provide very good online dealers manuals for their components which walk you through the full installation procedure and if followed to the letter, leave your indexing faultless.

Last bit agreed. But the routine you've found works for you is NOT the recommended Shimano installation procedure, is it? For a rear derailleur see pp17-18 of this: https://si.shimano.com/pdfs/dm/DM-MBRD001-06-ENG.pdf
(NB topic of thread) "if followed to the letter, [will] leave your indexing faultless.[/QUOTE]
Front one is different and hope you enjoy the 'job'.

 

[Lovacott]

Last bit agreed. But the routine you've found works for you is NOT the recommended Shimano installation procedure, is it? For a rear derailleur see pp17-18 of this: https://si.shimano.com/pdfs/dm/DM-MBRD001-06-ENG.pdf
(NB topic of thread) "if followed to the letter, [will] leave your indexing faultless.

I followed it to the letter last weekend including setting the stops in the shown sequence (my usual method though is to set the stops last so as not to confuse stop position with cable tension).

Indexing is great after last week but the front mech has a very weak return spring making changes down very slow (confirmed when my new mech arrived on Tuesday which has a spring which is almost impossible to move by hand).

The original mistake I was making was setting the stops as per instructions and then finding that subsequent shifting into one of the outermost gears wasn't working well and adjusting cable tension to try and compensate. At this point, I should have backed out the stop by a quarter turn first.

 

[T4tomo]

Its much easier to get the FD cable length correct with the LL screw in the correct place, ypu simply take all the slack out of he cable. UL doesn't matter and probably better dialed in last for the reason Lovacott mentions. i.e. Get FD height and angle etc sorted. set LL, set cable length, get happy with up and downshifts by tweaking barrel adjuster, dial in UL screw to stop it overshifting, make also need a fine tweak of LL screw at this point.

 

[Lovacott]

Its much easier to get the FD cable length correct with the LL screw in the correct place, ypu simply take all the slack out of he cable. UL doesn't matter and probably better dialed in last for the reason Lovacott mentions. i.e. Get FD height and angle etc sorted. set LL, set cable length, get happy with up and downshifts by tweaking barrel adjuster, dial in UL screw to stop it overshifting, make also need a fine tweak of LL screw at this point.

I've got a feel for how much cable slack I should have with the mechs in their completely relaxed state. Basically, it's a light pull through by hand. When I first started, I was pulling it taut with pliers before pinching up the cable. Obviously, this didn't work too well.

 

[nmfeb70]

Hi again everyone, apologies for not reading every reply but after a week or so the problem has returned. Despite the shifting being spot-on a few days ago, during my ride today it was hesitant in both directions - high or low, It seems to happen when I leave the bike for a day or two following a wet ride. I have eliminated the shifter and rear mech as the cause so I'm leaning towards a sticking cable inside the housing as the problem. I tried @DaveReading's suggestion and the cable seemed a bit stiff when pulled through the housing. I originally applied a little grease to the cable when replacing it, should I have applied a little lube instead? Thanks again, every bit of advice on here is invaluable!

 

[Lovacott]

during my ride today it was hesitant in both directions - high or low

Pulling the gears up (against the spring), a sticky cable will make shifting feel harder but the gears should not be hesitant.

Letting the gears out (going with the spring), a sticky cable can make the change sluggish.

I've fitted new inner cables recently due to fraying at the pinch bolts and I wiped them down with PTFE lubricant first. Anything oily or greasy can gunge up with muck.

Another thing which can make a cable stick is a fray catching on the inside of the outer cable (had this with my rear brake cable recently).

Cables are pretty cheap and don't take long to fit (make sure you have very good wire cutters though. Pliers won't do it cleanly).

 

[SkipdiverJohn]

I've had a weird erratic shifting fault which turned out to be excessive side float movement in a freewheel. You can adjust your gear cables until the cows come home but if the gear cogs are not staying in the same place it means nothing. Also check for unlikely problems such as a crack in the frame affecting the rigidity of the rear triangle.

 

[nmfeb70]

Pulling the gears up (against the spring), a sticky cable will make shifting feel harder but the gears should not be hesitant.

Letting the gears out (going with the spring), a sticky cable can make the change sluggish.

I've fitted new inner cables recently due to fraying at the pinch bolts and I wiped them down with PTFE lubricant first. Anything oily or greasy can gunge up with muck.

Another thing which can make a cable stick is a fray catching on the inside of the outer cable (had this with my rear brake cable recently).

Cables are pretty cheap and don't take long to fit (make sure you have very good wire cutters though. Pliers won't do it cleanly).

Could the wet weather have anything to do with it? I wipe the bike down but obviously not the inner cables. Could they seize after a day or two sitting still?

 

[Lovacott]

Could the wet weather have anything to do with it? I wipe the bike down but obviously not the inner cables. Could they seize after a day or two sitting still?

I don't notice any difference myself, but cables are totally exposed at some parts of the run so water must get inside the sheathing and cause a bit of rust if there is no coating on them (unless they are of a decent grade stainless steel). A few rides in the dry might smooth the cable off again where it contacts the sheathing but as soon as it gets wet again, new rust will form. In steel fabrication, most specifications allow 30 minutes maximum to get a primer coat onto a freshly shot blasted surface. Rusting happens very quickly.

I use cheap Clarks cables which are galvanised so I coat them with GT85 before I fit them and I give them a squirt every now and again (usually after I clean the bike on Saturday mornings).

If I pull on my cables by hand, I feel no resistance at all (no rub or anything else). If you are getting resistance with the cable disconnected from the mech, it's probably worse once the cable is tensioned because the contact pressure between the inner cable and sheathing will be greater.

The best way to find out for sure is to pull the cable out of the sheathing and have a look.

 

[Ajax Bay]

unless [cables] they are of a decent grade stainless steel
. . .
I use cheap Clarks cables which are galvanised

I recommend you take your own implicit advice and fit 'normal' stainless steel cables in future.
"Coating [cables] with GT85 before fitting them and giving them a squirt every now and again" is good practice for all cables.

I changed my rear gear cable and housing a week or so ago

If your cables are the normal stainless steel ones then, no, they do not rust let alone "seize" in a couple of days. This is most unlikely to be friction between the new cable and the new outer, except possibly at the cable outer ends. How did you cut the outers when fitting?

 

[Lovacott]

I recommend you take your own implicit advice and fit 'normal' stainless steel cables in future.

Over the last nine months, I've spent a fortune on my bike. I have a missus who hasn't been able to work and is on 80% pay and we have two kids to provide for (one at UNI who we are supporting financially as she can't get part time work at the moment). With the house being occupied a lot more than usual, heating and food bills have gone through the roof.

So although £40 each puncture proof tyres would be ideal and 316L marine grade cables would be lovely, I've had to try and keep my costs down.

So for me it's £2.50 cables, £12 tyres, £18 Chinese LED lights, entry level Shimano drivetrain parts, Clarks £7 chains and a £5 plastic box from B&Q secured with cable ties as a pannier box.

A galv cable does the job and GT85 along with a bit of TLC keeps them running smoothly.

Ultimately, I going to buy a better bike using the cycle to work scheme but until then, I just need to keep my current bike on the road.

 

[nmfeb70]

I recommend you take your own implicit advice and fit 'normal' stainless steel cables in future.
"Coating [cables] with GT85 before fitting them and giving them a squirt every now and again" is good practice for all cables.

If your cables are the normal stainless steel ones then, no, they do not rust let alone "seize" in a couple of days. This is most unlikely to be friction between the new cable and the new outer, except possibly at the cable outer ends. How did you cut the outers when fitting?

With a top quality pair of Draper cutters. It was as clean as a whistle.