badbikemechanic

+1

There is so much bad info here that I would recommend the op just take it to a competent bike shop and watch as the mechanic fixes it. Shimano ders are set outbound from the lowest cog and I think that is why he is having a problem shifting to the smaller cogs. Some folks don't realize that. Of course we are all staring at the bike through a internet board so it's hard to tell for sure.

A der adjustment runs 5-10$ money well spent imo

Al1943

It's nearly 3 years old, plenty of time to gunk up the shifters, especially if ridden in rain, happened to my 9-speed D-A shifters.

wrk101

+1 While I have used WD40 to free up shifters, its WAY down my list of options, as it is not a cure all. Making sure hanger is straight, making sure RD is not bent, installing fresh cables and housings all come before the WD40.

+1 Repairing over the internet? I would take it to a shop I trusted.

badbikemechanic

It certainly won't hurt anything, but based on the op's description I really don't think it is the problem. If it was gunk in there causing the issue you would probably have shifting issues intermittently on all cogs but the op clearly stated it is only happening at the lower cogs which suggests some other things. If it was a bent der hanger he wouldn't have bad shifts just on the lower cogs either, it would be unpredictably ghost shifting and its kind of obvious if you bend your hanger e.g. dumping the bike.

Based on my read the first things I would look at is the low stop screw, cable tension (of course), the length of housing going to the rear der., buildup of gunk in the cables (bike stores slick up cables for a reason -you buy more cables), and kinks or fraying in the the hosing.

My recommendation is that the op take it to a bike mechanic and ask to watch them fix it. If they won't go to another bike store. It's hard fixing bikes over the internet.

mechBgon

We were charging more than $5 to adjust derailleurs back in the '80s. Also note that the OP has already had the bike to his LBS twice.

Kimmo 

When I say the indexing stops are unaffected, I mean that the shifter always feeds an identical amount of cable for a given shift, if it makes the shift. Gummy grease does not throw the indexing out of calibration, it just stops the indexing from happening.

If you want to continue contradicting me, maybe overhaul some STIs first.

badbikemechanic

If this is the case than take the bike to a COMPETENT lbs.

badbikemechanic

Do you throw this link out there everytime you want to make a point? Nice epeen, but those shifters you overhauled are from the 90's. As you know that generation of SIS seizes up all the time road or atb. It is cool that you got in there and fixed it, but a cheaper more reliable solution would be to replace if a good dose of degreaser didn't free them up.

Based on the op's description of the problem - shifting problems that occur when shifting down not up- I would say it's not the shifters seizing up. When the shifters seize you can't shift down or up and it occurs unpredictably. Again throw some degreaser in there it's not going to hurt anything, but I highly doubt it will solve the problem.

badbikemechanic

Just read your post. It is definitely not the b screw. Demand they fix it or give you a refund.

Al1943

My issue with what you said is "if STI's are shifting, they are shifting properly", because this statement is not correct. STI's with hardened grease and/or dirt often shift sluggishly due to excess friction but may still shift. This condition is similar to poor shifting performance when the cables and housings need replacing. With dirty shifters the slow shifting response may be in either direction, like the OP's problem. With worn or dirty cables and housings sluggish shifting is more noticeable on out-bound shifts because a rider can apply more tension to the cable than the derailleur spring.

Kimmo 

Pff, as if Shimano has changed the principle STI operates on. Same principle, same issues; as long as both levers move in the same direction they'll keep using a variation on that 90s mechanism. The biggest change they've made is in the gear cable routing.

And replacing my levers would have been cheaper than overhauling them? Why am I even replying to this? They're still going strong, BTW...

No, it isn't similar. It's totally distinguishable by feel. If a shifter's failing, it's not a case of excess effort to shift to bigger cogs and sluggish shifting to smaller cogs; the lever/s will usually move without catching the shift mechanism, or do it intermittently. In which case, you'll feel almost no resistance and hear no click. Occasionally they may jam.

Geez.

Al1943

What you are saying does not agree with my experience with STI shifters. In many cases excess effort is needed to shift a dirty shifter.
And I said that shifter problems can be in either or both directions whereas that is usually not true with cable problems, so we seem to agree on that.
As I said above, my issue with your post #21 was that you said "if their shifting, they're shifting properly". That's not right, they can work poorly when dirty.
Also in post #21 you said they aren't intermittent, but now in post #36 you say they can be.

Kimmo 

In post #21 I said the OP's shifter's aren't intermittent. Or at least that's not what he described.

Therefore in this instance WD40 won't help IMO. Intermittent shifting is the failure mode. If the shifters aren't intermittent, I bet they're working fine.

And even if somehow they become stiff from crud (which would surprise me, given what I know of their workings), they won't put the derailleur in the wrong place if they do make a shift. Remember, the thread title worries about 'shifter calibration'. This is not an issue.

Unless maybe someone's tried to lube them with glue...

Al1943

Well Kimmo we agree on some things. I don't see any way that dirt or corrosion could change the indexing "shifter calibration" as the OP puts it.
My first recommendation to the OP was to take the bike back to the LBS that he had already paid to fix the bike. It seemed to me that the "calibration" issue could be a poorly routed cable at the derailleur or a bent derailleur, or derailleur hanger. After the return trip to the LBS he said that the bike seemed to be fixed at first but then started having problems again my thought was to try a WD40 flush because it can't hurt, it's cheap, and it might really help. Since he and the LBS seem to agree that the derailleur is pretty beat up I'm now thinking that the derailleur may be the real problem but I'd still try the WD40 first, then new cables and housings before spending money on a new derailleur.

Kimmo 

IMO it should be possible to determine if the derailleur's okay by checking it for for slop and straightness. The condition of cables can also be ascertained by inspection and feeling for friction.

An experienced eye should be able to evaluate those bits fairly well; there'd still be a slight amount of uncertainty, but it would eliminate the one dodgy element if only one element is responsible. Or, it could be a slight contribution of inaccuracy from each element, which is always a PITA...

But I'm almost certain the shifters aren't at fault.

joeturner

Although this is pretty much bringing this back from the dead, I figured I'd give an update on the situation. I basically dealt with having to shift twice until a week ago when I got an Ultegra RD for super cheap, installed that, calibrated and BAM, it's been great ever since. It seems that the heart of the issue was the derailleur itself, and not so much anything else.

Kimmo 

Yeah, if you have Shimano, swapping out the RD makes sense if you need to diagnose a persistent hassle; almost any Shimano RD should be compatible.