Just won't shift right
 

I recently replaced my 8sp sora/tiagra with 9sp tiagra/105. I can not get the new rear derailleur to shift correctly. I replaced all the housing/cable and lubed the cable with cable lube. The high and low are set perfect and the B adjustment is good as well. I have been playing with the cable tension for several days now trying to get the thing to shift correctly and I just can't get it. I put it on the second smallest cog. Then adjust it until it shifts perfectly to the next cog up. I then shift down to my smallest cog and back up to the top cog and everything seems like its great. Then when I try to shift back down from the largest cog the first click does nothing. The second click moves to the next cog down and will fall onto the next one and jump back and forth as you pedal. After the 3rd or 4th cog down it shifts smoothly until the smallest cog. I don't know what to try next. I think I've tried every adjustment position on the derailleur's fine adjustment screw. I am looking for a little advice. Any ideas?

it sounds like the derailleur hanger might not be perfectly aligned, or there is something inhibiting the cable movement, either sticky residue from sports drinks on the cable guide under the BB, or the lube you used is too thick, or there is too much of it in the housing. or the housing is slightly crimped at the ends where it was cut. or, the housing could be either too long or too short. the two lengths when it comes out of the shifters should overlap so there is a gap of about 1.5-2" at it's widest point. also, the last section of housing at the rear of the bike should have a natural curve to it, so it lines up with the RD barrel adjuster perfectly, but it shouldn't be so long that it flops around.

1. inspect the hanger
2. inspect the cable guide under the BB
3. check lengths of housing
4. drip some tri-flow into the cable housing to try to thin out the lube if it's too thick.

What do you mean 9s tiagra/105? A 105 chain and cassette on a tiagra RD? I did similar upgrades from 8 to 9 on both my mtb and my roadie a couple of months ago with the same exact problems on both. For my mountain bike I ended up taking out the cassette and tightening the screw/pin that holds the first 6 or so cogs together and then running through all the adj screws again and for my roadie I ended pushing the RD into the correct position for riding on the small cog before tightening the nut that holds the cable (needed two sets of hands for this). The number of chain links might be a factor, but I'm not sure (its a ? I just posted). Other than that I don't know what to say except for I know how frustrating it to not have it work after going through all the adjustments.

Oh, did you set all you tension adjustment thingeys (I have 3: in line barrel, downtube, and the screw on the RD) to the lowest level when tightening the cable to the RD? I find it helps a lil in later adjustments

Also check the cable routing at the rear derailleur fixing bolt.

Be sure the shifter is in the smallest cog position, flip the small lever several times and pull all of the slack out before attaching the cable. Be sure the cable is seated all the way in the shifter.

And it sounds as if you may have too much cable tension.

Al

Before I spend anymore time thinking about this answer one question:

Do your shifters and cassette match? Are you using a 9-speed cassette and 9-speed shifters?

Hey, make sure the cable is anchored to the derailleur the way it's supposed to go. Check the instruction sheet. If the cable is clamped on the wrong side of the anchoring bolt, it will pull slightly too much or too little (I forget which) with every shift, and will give bizarre results like you describe.

Also, I didn't think you were supposed to lube SIS cable.

I realize it's been a while, but I just had to say thanks for the help. It turned out to be the location of the anchor point on the dérailleur. It was just a bit further back than it should have been. I didn't think it would have made a difference with as close as it was to where it was supposed to be. But alas it wasn't perfect and it needed to be.

Thanks for all the responses and helping me nail it. You guys rock!