Hi Forumites!

Hopefully you guys can give me some insight as to what I'm missing:

Bike is well maintained, 10 speed 105 shifter, 10speed 105 rear derailleur, jagwire cable and housing. The 10spd cassette teeth are in good shape. Chain is in good shape. Jockey wheels spin freely, teeth seem unworn, and they engage the chain well. It's a ten speed chain, but not shimano. Chain is the right length.

Bike wouldn't shift properly on the cassette. I noticed that the cable tensioner was extend all the way out and wobbly. I ran it in and re-tensioned the cable so it was snug in the highest cog with the shifter in the most slack position. I didn't have much trouble getting it to shift crisply on the stand, but when rode it it would shift to lower gear (increased tension) smoothly, but when shifted to higher gear (decreased tension) it would hesitate and then klunk into place. Once shifted, it didn't make any complaining sounds, shift out or skip under high torque or anything else abnormal. But I found the shifting unacceptably rough for 105. Adjusting it to the point were it will shift to higher gears smoothly would result in lack of cable pull to shift to lower gears at all. I played with the dwell and it didn't significantly help. I have the b screw set so it doesn't rub but maintains the jockey wheel close to the cassette as it shifts. I tried it at various intervals before ending here.

I measured the chain, it's around 3 on a progold chain gauge. I measured its width with vernier calipers to make sure it was a 10spd chain and it matched an unused shimano 10spd chain I had. All links operate smoothly. I cleaned and relubed the chain and it didn't really help. The cable pulls smoothly and seems properly routed. The housing is all cut flush, as far as I can see. All the ferrules are in good shape. They are 4mm plastic. I couldn't find any weak parts on the housing or cable, unless it's under the bartape.

My only conclusion is I'm either missing something or the shifter itself is having some problem.

Thank you for any help, I really appreciate it!

You have not mentioned checking the derailleur itself, with the shift wire detached, for smooth, free motion.

Also check that motion of the loop of derailleur cable entering the derailleur is not hindered by grit or rust which tends to build up there and that the loop is properly sized.

It may also be time to check the condition of the cable housings under the bar tape and ensure that they have not pulled out of the shifter slightly.

It sounds like you are adjusting tension by feel only which won't get the shifting right. Start over from the very beginning of this guide Park Tool Co. » ParkTool Blog » Rear Derailler Adjustments (derailleur) especially note the part about setting the tension for the indexing.

I just bought a new Giant Anyroad 2 with the new 9 speed Sora and it had the same issues. On the smaller gears when shifting up it would miss the shift or only make a half shift. If you adjusted it where it wouldn't do that it through all the other gears out of whack. it took my LBS a couple of times to figure it out but it was the Jagwire housing. It would compress so the rear derailleur was slow to get moving. You were half way through the shift before the derailleur even moved. They recabled it with Shimano housing and that resolved the issue. I am not bashing Jagwire. They make good stuff and may even make Shimano cables for them so I don't know what the issue really was. But replacing the housing fixed the issue.

Housing doesn't compress. Not even the cheapest shifter housing. It may have been another problem with the housing or cables like bad routing or a kink but it certainly wasn't the housing's fault.User error or installation error.

You are probably right. If it was user error then that falls on Giant as it was a brand new bike. I know I had replaced the inner cable twice, and pulling on the cable it was nice and smooth. I had a spare 105 rear derailleur so I installed that which didn't help. I work by a different shop so I had them align the rear derailleur hanger but that didn't solve it either. So i went back to the LBS I bought it from so they could figure it out. Took them a while lol. Only after replacing the housing did the issue go away.

Have you tried cleaning the inside of the shifter with WD40? Shoot lots of it in there and see if it helps. Clean the c--p out of it.

As dsbrandtjr said, check for excess friction at the RD hinge pins. I had to soak mine in mineral spirits to free up the RD function.

Thank you for your good points. Yes, the derailleur seems to be functioning properly and smoothly when detached. The derailleur hanger is also true as far as I can tell. No grit buildup anywhere I could find. I am suspecting it might be under the handlebar tape too.

Sorry, I didn't mean to be confusing. This is basically identical to what I do. I've done it several times from the start (outermost cog and largest chainring, take off tension from cable, run in tensioner, give it a turn out, then tension the cable to 'snug', etc.) Sorry for the bad description. It shifts beautifully on the stand but when I go out to test ride it starts to shift otherwise.

I haven't tried new cable. That might be the solution, but I doubt it's brand specific.

I'll recheck the derailleur's range of motion, but I think it was good. I didn't clean the shifter. Didn't even come to mind, thanks!

Are you doing these steps specifically? Its not a matter of just tensioning until the cable is snug.