After replacing my chain I thought I would adjust my rear derailleur as it had been running a little noisily. First I carefully set the High and Low stops. With the chain running around the smallest sprocket I tweaked the Adjusting Barrel until it changed up to the second smallest sprocket and back again sweetly. I then clicked up a gear, turned the pedals and watched the chain hop up a gear. Here's the problem: As I get towards the largest sprocket the indexing goes out and the changes are erratic (this happens on approximately the last 3 sprockets). If I trim these in with the Adjusting Barrel the changes are poor back at the smallest sprockets!
I would be very grateful for some guidance here please.
Can it be that the index distance can be a fraction out which is accumulating as I go up through the gears? Is there an adjustment in the levers for the index amount?
(Sep 2, 2012 05:29 AM)TDC Wrote: ..... With the chain running around the smallest sprocket I tweaked the Adjusting Barrel until it changed up to the second smallest sprocket and back again sweetly. .......
This is the problem, the cable adjusting barrel should be tweaked with the chain running in the middle sprocket at the back, and middle (if a triple) or larger (double) at the front.
The smallest and largest cogs smoothness as the back is controlled bye the H/L limit screws, not the indexing.
Sheldon has some discussion on this - I am just feeling too lazy this morning to find a link for you.
Thank you for your prompt reply. I did adjust the B-Tension screw. My new bike's chain was too long, though I didn't know that for a while, and so I had to adjust the top jockey wheel away from the largest sprocket.
Some weeks ago I read the Shimano document again which you referenced and checked the chain length and found I needed to remove a link. I have since replaced the chain so I will look more carefully at the B-Tension adjustment.
Out of curiosity, how would this affect the indexing? I assumed that it would control the distance of the sprung assembly from the sprockets on a vertical plane.
Thanks for your suggestion. I'll get out in the garage and try that later.
Sep 2, 2012 10:32 AM
Veteran Member Illinois
Joined: Mar 2011
I use these steps to fine tune drivetrain shifting issues in the rear.
1. make sure all cable and housing and caps are in perfect condition and free moving in both directions. do not assume
2. True the rear wheel if it needs it and make sure it is seated correctly
3 .this is often overlooked because it takes a tool that the average joe may not have, but easily bought compared to a visit to the bike shop. the derailluer alignment tool use this to make sure that your hanger is in spec. I you are to dial the sweetness this is a must. do not assume.
4. set your high limit screw so that your pulley is slightly off center toward
the outside about 1 to 1.5 mm of the smallest cog.Set your low limit directly under the largest cog
5. make sure all housing is seated and shifter is relaxed and barrel adjuster is screwed in. Connect cable but do not push on derailluer by accident.
6. pedal and shift once. if it does not hit the second gear bring it back to high gear. if there is noticeable slack in cable reattach. if it hits the next gear, slowly 1/4 turn the barrel until you start to hear chatter then back off 1/4 turn to just where the chatter stops. run up and down the gears and see what she does. if it is firm to the lowest gear back out the low limit 1/4 turn till it hit normal.
the tech docs are available on shimano,s site for more info
the biggest mistake is having a derailluer out of alignment, the pully directly under the highest cog and an unknown bad cable, housing or cap snag
Thank you for a very comprehensive and helpful answer. Two items jump out: Cables and pulley alignment.
I will look for some guidance on cleaning and lubricating the cables. I had noticed that the inline barrel adjustment, where my cable appears from the bar tape, for my rear derailleur doesn't appear to actually adjust like the rear adjuster does. I can't find any information on setting these up but I wondered if it could be wound right off the thread and impeding the cable's movement a little.
I can completely understand how even a small mis-alignment of the rear mech' would have quite an effect on the indexing. It's not a cheap tool to buy just to check!
Good advice though. Thanks.
Sep 3, 2012 01:49 PM
Veteran Member Illinois
Joined: Mar 2011
lets see some pics of your setup. I assume you have brifters. Yes I know that particular tool costs but it is the way to go to fine tune like a pro.
maybe disconnect your cable and pull the housing out of the boss and see if you get movement out of your barrel adjusters.
you mentioned replacing your chain, if this was the start of your problem it may be time to replace your rear cluster also. keep digging
and see if your cable moves free with only light handheld tension.
Unless I missed it you did not mention your chain ring configuration so I will assume you have two rings. Be careful not to try to adjust your rear when shifting to extremes, i.e. big chainring to big sprocket and small chainring to small sprocket. These gear combinations should be avoided while riding and can really throw you off if you are attempting to regulate your RD. You should be able to adjust up to the first and second of the sprocket extremes with the appropriate chain ring using the advice given previously for setting the limit screws.
Also, make sure to make small changes and shift through the gears often as it may take a full circuit for your adjustments to take effect.
A quick update after last night's 'fettling'. Following Painkiller's advice I thoroughly cleaned and lightly lubricated my cables, including the inline barrel adjusters which I have now understood having taken them apart and cleaned them. I then started over again following the Shimano instructions carefully.
My setup is a Cannondale Synapse with Shimano 105 (5700) double FSA chainring front and standard 10 speed set at the rear. I have just fitted a new KMC X10SL chain.
I find that having set the high stop I then ensure I am in the highest gear using the lever with the cable slack, then carefully take in the slack and tighten the cable. I then click the lever to the next gear and while slowly turning the pedal wind the barrel adjuster until the chain hops up onto the second gear. I then wind the barrel adjuster 1 1/2 turns anti-clockwise to begin with and check the other gears.
Moving down the gears to the lowest (largest sprocket) all is well. When I try to return to the second lowest gear the chain is not quite pushed far enough and the chain rides up and the the teeth of the sprockets sit under the edge plates of the chain. To tune this out I wound the adjuster barrel back, clockwise, a quarter turn at a time until the down change is good.
Here's the problem, as I then return back to the highest gear the running becomes increasingly noisy. When back at the highest gear (smallest sprocket) and I try to change back down 1 gear it doesn't move. In winding the barrel adjuster back just far enough to allow for the down change at the lowest gear it now doesn't allow for a change up at the highest gear!
Sorry my reply is a bit long. B-tension could be the issue or hanger mis-alignment or is it possible to put a KMC X10SL chain on the wrong way around? My previous Shimano chain had a front and back face.
I'll send some photos later. Thanks for making your way this far.
The weight of opinion appears to suggest mis-alignment of the rear derailleur so I've ordered the Park Tool DAG-2 alignment tool (£45 inc. VAT from Tweaks Cycles). When it arrives later in the week I'll post my findings.
My Park Tool Derailleur Hanger alignment tool arrived yesterday and I tried it on my bike last night. As suggested my hanger was mis-aligned (about 1cm difference 3 O'clock to 9 O'clock and a little less top to bottom).
A few thoughts to those who have been reading this thread with similar issues:
My Cannondale is less than a year old and, to my knowledge, has never had the slightest knock to the rear derailleur. I think that the rear derailleur has never been aligned correctly but I think that the original Shimano chain is more forgiving than my recently fitted KMC X10SL chain. Perhaps the Shimano chain is slightly slimmer.
Using the Park Tool DAG-2 to lever the hanger into alignment I did wonder if this could stress the slim carbon rear forks?
Anyway, after putting it back together I set the indexing from scratch again and this time it changed all the way up and back down again without the chain riding up onto the sprockets on the lower (larger) gears.
Thank you everyone who took the trouble to contribute to this result.
Sep 12, 2012 12:52 AM
Veteran Member Illinois
Joined: Mar 2011
I am glad it worked out for you. I check every bike I do new or used because you are right, they quite often come in out of alignment. sorry for
the pain of having to buy it but in the long run you will be glad you did.
did want to mention one thing,, if you still have some trouble the next thing to replace would be your rear cassette, it may be getting worn also.
Hi. I did wonder about the rear cassette as it still 'chatters' as I turn the crank. The noise appears to be mostly coming from the two pulley sprockets, particularly in low gears when the hanger is wound up. They don't look worn though. I'll get out on the road at the weekend and see how it all runs.