tuning the gears

Sprool

New bike's well into its 3rd week now and nearly 200 miles clocked up. Still struggling to tweak the gears for smooth changes and no rubbing, esp the front derailleur - its a tripe ring crank, tiagra shifters (with a trim position), 105 on the back, 9-speed Sram cassette.
Trouble is, I tweak the barrel adjusters by the brakes in my workshop, get it running sweet then after a short time on the road its rubbing again. Can it be that the cables are still stretching? Seems more likely to me that the barrel adjusters are returning to their earlier position. When I'm rotating the barrel adjuster I'm not convinced I'm achieving much! Any clues? Bike's a Scott S30 2011.

Anonymous

have you tried the barrel adjuster on the rear dérailleur? Just where the cable goes into it?

woodywmb

Sprool wrote:

rubbing, esp the front derailleur - its a trip(l)e ring crank

It won't be the barrel adjuster on the rear if it's the front derailleur. Triples are harder to get right because of the chain angles created within the derailleur cage. So you have to persevere. Always have your chain on the middle ring when altering the adjuster. Look down as you turn it and watch the cage move backwards and forwards. Pull the exposed section of cable as it runs under the top tube or down tube. This enables you to experiment with the precise setting of the derailleur. Oil up the adjuster and grease the cable at the point where it runs under the bottom bracket. You will then get more movement as you cycle along. Try the bike on a long straight road with no traffic. Turn the adjuster at the shifter as you pedal and change gears up and down. This will let you experience how it's operating under pressure. (No pressure in the workshop when you're not in the saddle). Even the bike shops can't guarantee it will work completely out on the road after a bit of fettling in their workshop. Keep at it and you'll master the procedure.

Sprool

i can get them tuned in ok for a short time, but I fear the barrel adjustment is slipping so after 5 miles its back where it was again making the chain rubbing grating sound. Is it normal for barrel adjusters to slip back or am i still getting cable stretch?

night_porter

Woodywmb wrote:

Sprool wrote:

rubbing, esp the front derailleur - its a trip(l)e ring crank

Try the bike on a long straight road with no traffic. Turn the adjuster at the shifter as you pedal and change gears up and down. This will let you experience how it's operating under pressure. (No pressure in the workshop when you're not in the saddle). Even the bike shops can't guarantee it will work completely out on the road after a bit of fettling in their workshop. Keep at it and you'll master the procedure.

+1

It could be that the cable adjusters are at their limit though or the allen bolt holding the cables is not tight enough.

Then you will need to adjust the cable and tighten properly, if you do this make sure that the barrel adjusters are all the way in before you tighten so that you have maximum adjustment in the future.

Sprool

thanks i'll check that out.

CiB

It could be the barrel adjusters. I ran Ultegra until earlier this year and regularly saw the same issue, that the fine adjustment on the barrels didn't stick for long and they always seemed to wind back to min adjustment over a few weeks, unnoticed. In the end it was easier to adjust by trial & error at the clamp + adjustment at the rear mech. It took a bit of faffing but once it was right it was right and stayed right.

Best tip is chuck em away & buy some Di2 instead. No cables to stretch & adjust; indexing is an absolute doddle that you do once and then leave, or do it now & again for the fun of it.

HoHoHoBlueGiant

+1 for the barrel adjusters winding themselves back in. My Giant has Tiagra and does exactly the same.

I don't use them now, just get the cable tension correct using the cable clamp.

It was rather frustrating until I worked out what was happening.

Sprool

Dont think I can justify expense of Di2s on a £700 bike. Maybe some better barrel adjusters that stay put?
Thanks for the comments. I've screwed both adjusters at the brifters down to min, as well as the adjuster on the rear derailleur, then taken up a couple of mm slack at the allen bolts. Rear one is fine as theres the adjustment there but the crank ring front derailleur has no other fine tuning than the barrel adjuster thats slipping as I ride. LBS says its just cables stretching but I'm pretty sure thats not going to happen after nearly 200 miles. Its due its first service now anyway so I'll have another chat with them when I take it in next week.

Sprool

quick test run with tweaked cables and barrel adjusters at minimum. That's finally how the gears ought to be shifting! No movement during the ride, clean and positive. Now what remains is a pair of useless barrel adjusters that slip and no way of decently fine-tuning the front derailleur.

CiB

Can you not do the same trick on the front mech? All you're trying to achieve is the correct cable tension when it's on the smallest ring - i.e. probably v little or even close to zero tension at that point. That's all the barrel adjusters give you.

Perhaps you could ride it around, adjusting the barrels till it feels right. When you get that, drop in onto the smallest ring & feel how much tension there is then wind the barrels down to zero and adjust the cable on the front mech clamp till you achieve the same zen-like perfection. That should do it. Might take a few stabs at it but it'll be right when you've done it.

slowondefy2

The barrel adjusters on my 2010 Tiagra shifters move on their own as well. Generally it's only the rear mech shifter that moves. To be honest I've not made any efforts to fix the adjuster in position, I simply keep it adjusted whilst I'm riding - I find it easy enough. Rough roads are the worst, it's the vibration that makes it turn. It's pretty annoying but I forget to fix it when I'm back home!

Sprool

Anything I can do to prevent the barrel adjusters slipping back again when adjusted? Maybe replace them with something that has a ratchet? I want to retain the convenience of trimming them but can't keep stopping every mile to retighten them. Maybe a bit of insulating tape to make the thread bite more?

woodywmb

Never ever heard of this before now. The adjuster should always be under pressure and therefore wouldn't move as a result of vibration. The adjuster itself is designed not to move of its own accord. I have checked with Shimano's distributors and they have never heard of slippage with today's adjusters. Can you provide more information - picture, serial number, detailed description of what's happening? In fact can the other posters provide more detail about their experiences? Also, you can replace the cable and insert a higher quality inline adjuster anywhere that suits you or the frame.
http://www.chainreactioncycles.com/Mode ... tAodWn0AqQ

Monty Dog

Could be down to sloppy threads in the frame-bosses? Wrapping a turn of PTFE plumbers tape should keep them snug - but like previous poster, it's not something that I've come across. Also, have you made sure the outers are fully seated? Pull down on an exposed length of inner cable (gloved hand helps) and then try re-setting the gears, undo the cable clamp bolt if needed. Also start with all mech-adjusters fully wound-in.

Sprool

http://www.ebay.co.uk/itm/New-Jagwire-M ... 4a7&_uhb=1
These are the type of barrel adjusters the Scott S30 came fitted with, (identical but unbranded) on the Tiagra 4500 Brifters. I have since found some more posts on other forums about these little chaps slipping with road vibration, so I'm guessing this may not be that rare. You can adjust them in the garage before you set off, and see the extra amount of black sleeve protruding when its tightened. After a few miles its vibrated back in again slackening the cable and the protruding black sleeve has gone again. I have ordered a pair of Jagwire Rocket II adjusters to try out, they at least have a sort of ratchet lock like the adjuster at the back of the rear derailleur mechanism. The outers are fully seated, because you can visually see the amount of tightening with the inner black sleeve, and it going back in again with some road vibration, I know there is nothing else going on with cable seating or cable stretching. It is the barrel adjuster rotating back in again.

slowondefy2

FYI, my barrel adjusters are also Jagwire as fitted to my Tiagra Giant Defy 2. They look a bit different to the above, they're like this.

gazhilla

Can you get them set up and try a drop of locative threadlock? It is a glue that sets but with a bit of force unlocked! Might help . Easy way to check if unwinding is setting up then two dots of tip ex, one on adjuster and one on cable in line. Ride out and see if it moves.

Sprool

It moves. You can see it in the length of sleeve poking out. I put a notch on them and you can see its rotated after a short ride.
Trouble with threadlock is that I then lose adjustability once the bond is broken. Thinking maybe the PTFE tape might gum it up enough to give more resistance to rotation, but still allow some adjustment when needed.
Poor design annoys me.

CiB

Sprool is right. I used to notice it on mine, that the inner would have gone back inside the outer after some miles. That's why I suggested leaving them and spending some time adjusting the gears without involving these barrel things. They clearly don't work as expected so it's easier to ignore them and leave them out of the equation. The fact that they work for some people isn't much help to those who find them unwinding.

Sprool

I've completely unscrewed the barrel adjuster and wrapped a thin section of insulating tape round the inner thread then screwed the outer adjuster back on, it's certainly harder to turn, I'll see next time I take the bike out if its enough friction to make it stay put once adjusted.