The B

Howdy

I posted on roadbike... no solution... so I figured I'd try here.

105 10-speed rear derailleur is shifting super slow/sloppy/or not at all. Through the cogs, it will refuse to shift down without coaxing the shifter, or if trying to shift up it will require an extra click and then click-back, or just jump the cog I wanted entirely.

What I've done:

Cleaned the **** out of it, re-set limiters (original symptom was just refusal to go into 12 cog, thought it might have gotten outta whack)
Inspected, cleaned, lubed cable and housing, verified cable has no breaks or kinks all the way through to the shifter stud
Reattached, tensioned, and adjusted for tension
Checked derailleur hanger- was slightly bent. Straightened
Adjusted B screw
for what it's worth (I have no idea) I TRIED to gage the amount of cable being payed out/taken up by shifter, and it seemed consistent, but all I did was put a scale (machinists ruler) on the thing and tried to eyeball-verify... It seemed consistent to me
Re-checked cable runs freely through both housing
Re-lubed housing
Rammed head against wall
Stared at it
Cursed it
took it off and put it back on
Re-tensioned it again
checked alignment again
and on
and on

What am I missing?

Thanks

Jeff Wills

Are all the cable housing ferrules in place and in good condition?

FBinNY 

The key to a problem like this is to isolate the cause to either the RD, levers, or cables.

Start with the RD by shifting to high, then shift through the gears by drawing the bare wire away from the downtube like a bow string. Other than a question of your touch and trim, it should respond cleanly and crisply in one step shifts for either direction, with no binding or jerking as you do so. Test the 2nd high to high shift this way a number of times, because that's were they sometimes like to hang up.

If it doesn't pass these test, there's a good chance that there's cable binding in the chainstay/RD loop which is the first to go in most systems. Or it could be a derailleur adjustment, such as the B screw letting it ride too close to the cassette. Also know that an older chain or a poorly lubed one (not saying this just because I sell chain lube) often shift poorly, so lube the chain.

Once you've cleared the RD and RD cable loop, it's time to test the levers. Shift the RD to low, and let it hang from the sprocket, or if it won't, tie it to the wheel with a piece o string (do not turn pedals for a while). Now test the lever in both directions using the bowstring method to keep tension in the system. You should feel clean solid movement for each click. If it feels gummy or not solid, spray the levers out with WD-40 or something in case dried grease is gumming them up, let them dry completely and lube with a teflon oil or aerosol grease.

Lastly, if you haven't isolated the cause, return the system to normal, adjust trim for clean down shifts (toward big cogs) and see if the upshifts are OK. If the upshifts delay, try a one click upshift followed by plucking the wire away from the frame like a guitar string. Pluck hard, and if that makes the difference in completing the shift and trimming right your problem is probably in the handlebar to frame housing loop. BTW- I often do this test first because it's easy and so revealing.

So there you have it, divide and isolate, then look closer at the suspected area.

venturi95

Please tell me how you straightened the derailleur hanger.

The B

Update

Der shifts up and down great, pulling on the down-tube cable by hand. So I guess that answers that question, FB - problem must be on the front of the bike.

I notice that when shifting up from multiple gears, the clicks on the up-shift lever go from sharp and snappy to softer and almost mushy, like it's losing cable tension. If I shift down from 12t to 13t, then click back to 12, it's a sharp click going back into 12. But if I click through the range from a few cogs over, by the time I get to 12, it's barely clicking at all.

I remember that back when we got our first cold snap, the right shifter stopped clicking below around 20F degrees. Once I figured out that it was the cold doing it, I just forgot about it- it usually doesnn't get that cold around here and I keep the bike inside. But obviously that means the grease inside is probably gone gummy..... so remembering this, I gave it a nice good zap of WD40 last night and let it soak. Today, it does seem to click better, and shifting seems to be improved... but it's still not right.

So I guess next move is to check the cable housing up front again... I already cleaned and lubed it up really good (it was clean to begin with) and verified the cable runs smoothly when it was disconnected... housing runs along about as smoothly as I think you could ask for, but maybe something is binding once the ferrule goes back into the cable boss? Or maybe it's the shifter...


Edit - Edited the original post title to reflect the fact that it isn't a der problem at all.

The B

Conclusion -

Just replaced the housing.... bike now shifts like new.

So I don't know how much of the other things I did helped, but apparently the front housing was the main culprit, if not the exclusive culprit.

Funny how that works... cable looked perfectly good to me, cable ran through it like buttery silkness when disconnected... but the inside liner must have been rubbed out or something, 'cause installed and under tension, it was hanging me up.

Thanks for help, gentlemen.

FBinNY 

As you see, the key is to divide and isolate, then rule in or out.

Retro Grouch 

That's always my first thought too. With a 10-speed cassette it doesn't have to be very far out of whack to screw up your index shifting.

The B

I used a steel straight edge and a scale to gauge it, and then used a piece of bar stock to torque it. It's certainly more awkward than using a hanger bar, but works almost as good (or as good, if you're really patient)

onbike 1939

Using a logical progression may be slow, but you do know that you're going to get there in the end.

rydabent

The "B" screw if very important in how your bike shifts. It is probably the most misunderstood adj on the bike. Contrary to conventional wisdom it is NOT a chain "tension" screw.

The "B" screw needs to be adjusted for a clearance between the jockey wheel and the largest cog on the cassette. For instance the distance between the jockey wheel on my Sram 7 RD is stated to be 6mm. The best way to measure that clearance is with a 6mm allen wrench in my case. Adjusted to the proper clearance it will assure quick crisp shifts, and will not let the chain bind or jam between the largest cog and the jockey wheel.

The B

I adjusted it for 2-3mm of clearance between the pulley tooth and largest cog tooth... I'm told that's the best distance, in general, to give it enough clearance but still allow the sharp torque on the chain required for quick shifting