Rear dérailleur woes.

My road bike has a 105 11spd rear mech, which I’m having issues with.

Firstly, I have fitted new cables to try and sort it already.

If i put in enough tension to get the chain to move up the block, it sticks on the way down. I initially thought the rear mech spring felt very weak, so i bought a new mech. . No difference.

Im thinking possibly the mech hangar?

Did you replace tge outer cables as well as the inners?

Yes. no noticeable stickiness in the cables either.

Maybe teaching you to suck eggs if so sorry

I seem to break more than my fair share of rear mechs on the trails so have replaced them more than I am happy with.

Make sure that the shifter is defiantly in top gear ( hit the trigger a load of times ) I have also trapped the cable in the with the maintenance stand on more than one occasion.

I set the limit screws without the chain on just push the mech for low gear and let it relax for high.

Set the adjuster on the shifter somewhere in the middle

Do up the cable, getting the tension here right here is the trick, no slack but no real tension.

Fit the chain if you have not done so

Run the through the gears on the work stand and use the adjuster on the shifter to tweak the changing.

I am not trained bike mech and there may well be a better way ( which I would be happy to learn )

Only once ( on someone else’s very old bike ) I have came across a broken shifter.

Righog – no need to apologise! Ive done pretty much as you have said. I build all my bikes from frames, so like you have set up quite a few.

This one has me scratching my head. It must be the cable snagging on something, but god knows if i can see where.

Too Late for an edit….Just realised road bike, not much difference but obv. the adjuster will not be on the shifter 🙂

Good luck Dan I am just heading out riding now, hopefully I will not total another mech tonight !

Are the ends of the outers smooth and open?
Chain the correct way?
B screw?
Cable passing to the correct side of the cinch bolt?
Cable run, kinked? How does it do under the bar tape?
Nothing else springs to mind.

Good luck,

APF

APF – the only thing I haven’t checked yet is the short run of outer under the bar tape to the inline barrel adjuster. Its only about 10″ long, but I’ll take it apart when I get a chance.

Are 11spd setups much fiddlier than 9/10 because of the narrower spacing?

Yes a little. I ended up fitting a fine barrel adjuster inline on my rear deraileur cable… Just could not get it spot on with the rather course adjustment on the frame barrel adjusters. Literally 1/8 of a turn on the adjuster is enough to throw it out of the “sweet spot”. However I am a bit anal and it still shifts fine up to a full turn out.

Definitly a little more sensitive than my 10 speed setups.

My bet would be b screw. Assuming (and It sounds like you have) ruled out all other options. Check the bend radius around rear mech…. 11 speed setups work best with a nice sweeping bend of outer.

A nice long run into the mech is a good suggestion.

APF

Have had similar problems in the past with a stretched chain – possibly worth a look if those adjustments don’t work.

This is the rear cable bend. too tight?

I have to admit I have found the b screw makes naff all difference, as opposed too my SLX or SRAM Rival, the 105 one seems to make no difference to the position of the jockey.

Looks fine that to be honest. b screw does make a difference but hard to quantify as it’s a dual spring… Unlike slx etc which drives the position of the guide pulley to a hard stop. B screw for me on my 105 11 speed setups adjusts what I call “snapieness” of the shift. Less tension on guide pulley (b screw turning anti clockwise) slows down the shift slightly and induces a bit of dwell. B screw tight (clockwise) almost all the way in, improves shift time.

As stevious says…. Have you checked chain wear? What chain? How old is cassette? Check guide pulley for play… Little bit of side to side play normal (and needed) but not too much!

I haven’t checked chain wear recently – it might be nearly due a change. Would that really change the shifting up & down the block? Its a 105 chain & cassette.

Basically, I have adjusted the High stop & cable so that the jockey sits right over the 11T with the cable just taught. If i then adjust tension to get the mech to rise nicely, as soon as I come off the large cog, the chain rubs the large cog & jumps. In the same gear on the way up, it doesn’t do it, which leads me to surmise it must be a sticky cable somewhere.

Thanks for that b-screw explanation. that makes sense.

Recently I found that a new Campag inner cable I fitted was too thick a gauge to run freely in the new Clarks cable outer I’d used and caused the same issue as yours.

Sounds like the mech hanger may be slightly bent as when it is in the large cog any misalignment will be amplified due to the angle of the mech cage

Ive ordered a new mech hanger, and a new chain is on its way.

Ive used the same inner/outer combo for ages on cables, so shouldn’t be that.

You can tell by eye if the hanger is bent (maybe not if it is twisted).

Chain wear shouldn’t cause it.

try a 1.1mm inner.

I’ve had a problem with my 105 mech. The pivot point had some pay in it, probably from a crash! ! Seems to effect the travel across the block & mahjong it non linear. I need a new mech really but the shifting is almost tight so it’ll do for now! !

Your new hanger might be bent too. Get the current one straightened properly. With a tool.

Thanks all – lots of things to ponder. I’m out of the country for a few days – will post up what the issue was once it’s sorted.

Internal routing?

Check cables are entering frame and exiting on the correct side and are not crossing over (rubbing together) mid downtube.

Have you tried pulling the cable in and out with your hand while shifting?

Dirty dog – it is, and I have checked. done that one before!!

Globalti – no, but that sounds a good idea to check if its a cable issue.

Shimano Polymer cable and SP41 housing?

If you’ve not changed the gear outer under the tape that would be my first port of call.

Two things I’d look at…..
If you have one of those plastic cable guides under the BB, I’d give that a clean and a spot of grease
Failing that, if you’ve retaped the bars make sure the cables have the largest radius they can get so that the outers don’t pinch.

*is glad to be on 8 and 9 speed*

Most usual reasons are…

1. Too tight a bend at the rear mech.
2. Radius of bars too tight, some gear cables are better than others at following tight bends. Don’t go mental on the electricians tape.
3. Mixing and matching inners and outers.
4. Dirty outer cable cuts.

i’ve had this very problem of late and it’s beaten me…

the issue is when the cable is taught against the bars and bar tape is applied… i though i was going mad for some time.

i’d indexed the gears perfectly, got the bike running like a dream, and finished off with the bar tape, then BOOM the derailleur wouldn’t drop back down the cogs (big to small)… in the end i took it to the bike shop for them to fix it… picking it up next week, can’t bloody wait

Well – still waiting for a new (2 actually) mech hangar to be sent from Italy, but I decided to completely strip and refit the drivetrain.

Finally, I have the culprit I think. Dirty Dog is the winner! I was sure it wasn’t the case, but when I undo the front mech cable, shifting is perfect. So there is a crossed cable internally 😳