City Guy

HI

Working on my 2017 Giant Contend, rear shifting was inconsistent and was time to replace bar tape and after approx 17,000 km, decided to replace all cables and housings and time for another new chain (Shimano 11 speed Ultegra). However, unable to adjust rear derailleur for consistent shifting. So new chain, new Jagwire stainless cables and housings .Limit screws set properly and derailleur hanger aligned correctly.

When adjusting the rear derailleur, shifting is inconsistent, will shift up perfectly from 11 cog to 32 cog, then halfway down cassette, won't shift to next smallest cog until I reduce cable tension, then makes the shift. Then when finally down to smallest cog, won't shift up to larger cogs until cable tension is increased, then same scenario on shifting down. Can't adjust cable tension for proper shifting through entire range of 11-32 cassette.

I have checked for all the issues I can think of, cable heads seated properly in shifter, smooth cable travel, checked hanger alignment again, checked limit screws again made sure new chain was 11 speed.
Any ideas?
The only cause I can think of is possibly a worn STI shifter, Do these STI shift levers (internal mechanism) wear to the point of inconsistent and poor shifting performance?

Thanks in advance for any ideas, much appreciated> Max

Crankycrank

Check if the cassette lockring is tight. If the cassette was taken apart some dirt may have gotten between the spacers when put back on. Shifting can hesitate if the cassette is worn and will usually give you a clue by skipping on some of the cogs with a new chain but not always. Shifters rarely wear out in 17k km but could need a flush and lube. Make sure the derailleur moves freely without cable tension. Check the B-tension screw which is not likely out of adjustment if not damaged or a new, different gearing cassette was installed recently but check just to be sure. Jockey wheels worn or bolts not tight? Is the wheel mounted straight in the frame and bearings not loose? That's all I can think of for now.

dsbrantjr

Shifting up but not down or vice versa sounds like a symptom of excess friction in the system. Check that the housing ends are properly prepared, with square ends, clear openings and no reinforcing wire ends sticking out. Make certain that the lengths are correct so that the ends enter their sockets square; this is especially important for the last run of housing going into the derailleur.
Ensure that the housing is firmly seated in the shifter and has not been dislodged by the bar tape. Make certain that the proper ferrules are fitted where needed and are undamaged.
Check the derailleur for wear (sloppy pivots).

Iride01 

When you put the cable in the holdfast did you ensure the shifter was shifted all the way to the 11th gear by repeatedly pushing the small paddle and pulling on the bare cable until it wouldn't go any further?

Sort of sounds like the shifter is in the 10th gear position when you are setting the cable with the DR in the 11th position.

You didn't mess with the low limit screw did you?

City Guy

Hi

Thanks all for the suggestions. I will check all the and make sure suggestions are implemented. Since cables and housings are new, perhaps this a likely problem I'll check thoroughly for any excess friction. Also fairly certain cable was attached with shifter in smallest cog position, but will check again.

THANK YOU ALL, Max

Andrew R Stewart 

Also check for the shift cable being clamped to the der properly. It's easy to mess up which side of the anchor bolt and "washer" (often with a tab) the cable is to be placed. Andy (who is surprised that no one has mentioned the beloved hanger alignment aspect)

dsbrantjr

The OP states that the hanger is in correct alignment.

City Guy

Hi Al,,

This afternoon I re-checked all the items that were suggested, and found nothing that was mentioned as a possible cause.

At this point I can only think the STI lever is causing the problem. I understand these 105 STI R7000 levers are not serviceable and I may try to degrease/clean the internals from outside the lever, and re-grease with a spray grease that was mentioned in another post avout STI shifting issues.

Thanks again for all the suggestions and advice.

SoSmellyAir

In addition to all points noted above:

(1) Did you accidentally use a brake cable as a shifter cable? Maybe try Shimano's own shifter cable. The rear derailleur should have a barrel adjuster built in and so does not need a cable with a barrel adjuster.
(2) Does your new cable path follow the exact same path as before? Or is it tangled with another cable in the frame? If you had trouble routing it, you may have trouble shifting it (according to a mechanic at a local bike shop).
(3) Did you leave a nice, big, fat, not too tight radius loop of cable from where it exits the right chain stay to where it enters the rear derailleur? (The same mechanic explained the need for this when I asked him to shorten the loop on my bike for aesthetic reasons.)
(4) Are your rear derailleur pulleys, especially the guide pulley (top one), worn out? (Even if not, an upgrade to Ultegra pulleys is only around $20. That gains you 1/4 watt!)
(5) Check to make sure that there is absolutely no movement of any cog in the cassette relative to the freehub. Try removing and disassembling the rear cassette, washing and drying the individual pieces, then reassembling and reinstalling it. It is easy (especially working in less well lit conditions at night) to mess up the rotational alignment of the outermost cog (11T in the case of a 11-32 cassette) because the splined freehub does not extend through the entire width of the cog. This leads to the outermost cog being out of alignment and the rest of the cogs being slightly loose.

I also second Andrew R. Stewart's point above re: checking on how the cable is routed through and clamped onto the rear derailleur.

I have the prior generation of 105 (5800) derailleurs, and for adjusting the rear derailleur, I follow Calvin Jones of Park Tools' video:

Rear Derailleur Adjustment | Park Tool

City Guy

Hi

Thanks for suggestions, Checked all 5 suggestions and no issue found, and derailleur hanger is aligned correctly. Still suspect the problem is with STI shifter.

SoSmellyAir

Have you ever crashed or dropped the bike on that side?

Maybe just buy the following and redo the shift cable again.

Shimano OptiSlik Inner Shift Cable [Y60198100] at WesternBikeworks

Otherwise you have no option other than to visit a local bike shop.

mrrabbit 

1. Disconnect all rear housing and cable.
1a. Check and correct rear wheel dish.
1b. Align derailleur hanger parallel to properly dished and installed wheel.
2. Use your hand to manipulate the derailleur to the uppermost position, hold and set the limit screw as noted in the documentation.
3. Let derailleur rest to lowest position. Set the limit screw as noted in the documentation.
4. Install housing and cable...no tension, but no slack either. Should stay on smallest cog with no slack or tension.
5. Bring derailleur up to 5 or 6th cog position, adjust barrels until cog position correlates with shifter position.
6. Test shifting 1 UP and 1 DOWN - adjust barrels to make minor adjustments.
7. Shift front.
8. Test shifting 1 UP and 1 DOWN - adjust barrels to make minor adjustments.
9. Shift to largest cog, make sure limit is correct.
10. Shift to smallest cog, make sure it shifts to smallest cog on its own with NO assistance AND limit is correct.

Road test...

=8-|