jlaw

Hello mechanics!

I understand the how the rear derailleur, Hi/Lo screw, barrel adjuster, and B screw are supposed to work and how to adjust them. I've also watched the Park Tools and Art's Cyclery videos re: this several times.

Here's my situation:

I put the chain on the large chainring and the small cog. Then I make sure that there is no tension on the shift cable. After that I adjust the Hi screw so that the chain rides properly on the small cog. Next, I take up tension using the barrel adjuster (counter-clockwise) until the chain starts to lightly hit the second smallest cog - then I back the barrel off (clockwise) until the chain once again just rides properly on the smallest cog. Everything works up to this point.

Next, I shift up one gear to the second smallest cog, third smallest, etc - and use the barrel each time to adjust as nec.

The problem is that I can get the four smallest cogs to shift well as a group - and I can get the 6 largest cogs to shift well as a group, but I can't run through all 10 without significant issues. It appears that the adjustments in one group mess-up the shifting in the other and vice-versa.

I'm running Dura Ace 7900 DT shifters with a Shimano 105 RD and a Nashbar 10 speed cassette (11-32).

I took the photos shown below. It looks to me that the derailleur cage is skewed noticeably when the chain is on the smaller cog.

Opinions? Ideas?

Thanks.

GrainBrain

Can't really tell anything from the pictures, but I always make sure to have some tension in the small cog. Usually I'll back the high limit out, and make sure the shift cable isn't slack. I'll set the barrel adjuster in the middle. Then I'll adjust the high screw in till it starts to make noise, then back it out. There should still be tension on the cable.

Shimano recommends you fine tune indexing between the second highest cog and third highest cog with the barrel adjuster.

Troul 

Adjust the barrel first and then turn the h L limit screws.

ThermionicScott 

It does appear that the tension pulley end of the cage is skewed outward a bit. One giveaway of a bent derailleur hanger is indexing that works better in one chainring versus another.

jlaw

I've decided that I've spent enough time frustrating myself with this. I think you may be correct so I'm going to take it to my LBS to have them check the alignment of the RD. Thanks.

cyccommute 

Your problem has nothing to do with anything on the derailer. Your hanger is bent...twisted, actually. It's very easy to see the problem from your photos. No amount of fiddling with limit screws or barrels is going to fix it. You need to carefully bend it back in alignment. If you have a derailer alignment gauge, it takes about 5 minutes but that's not a tool that the common home mechanic has. Take it to a shop.

By the way, I see 3 to 10 of these a month at my local co-op. It's the second thing I check when someone comes in complaining of poor shifting. I had to do 3 of them last Saturday alone.

On another note: Kudos for the good pictures. All too often people take pictures from weird angles and/or out of focus. Your's clearly show the problem.

dsbrantjr

Yes, clear, well-focused and well-lighted photos, taken at sensible angles, can go a long way towards helping us help the OPs.

toddbiker

Straighten/Align Bent Derailleur Hanger Without Special Tool

TimothyH

There is no need to adjust index on every sprocket.

Adjust it on one sprocket in the middle of the cassette and it should be good for all sprockets.

If it is adjusted properly on one sprocket but doesn't index properly on another then something else is wrong.


-Tim-

gsa103

Shimano procedure is to index on the 3-2 shift (1 being the largest cog). When you push on the shift lever you should hear the chain clicking but not actually shift until the shifter actually clicks.

Vefer

Um, the Dura Ace shifters only play nice with other Dura Ace parts. They are slightly different pull ratios and spacings.

Kontact

Nope. DA 9 and 10 speed work with all other Shimano road 9 and 10. You're thinking of 7400.

jlaw

I took the bike to my LBS today and the mechanic found two issues.

1) The RD that I installed was an 11 speed RD - which I knew - but I thought the RD was simply a dumb, spring-loaded mechanism that will pull the amount of cable that the 10 speed shifter tells it to. According to the mechanic the geometry of an 11 speed RD makes it specific to 11 speed cassettes. So, he popped on a 10 speed RD and was able to adjust the index successfully.

2) The RD hanger was misaligned (horizontally) by about 1.5 inches when the alignment tool measurements from 9 o'clock and 3 o'clock were compared. The 12 o'clock and 6 o'clock meaurements were pretty close. The horizontal misalignment may have been partly due to me putting a new 130mm hub into a 126mm rear spacing - but the hanger was also tweaked a little besides. I held the bike and he horsed the alignment tool a bit and got it close to equal.

Conclusion - the bike now shifts flawlessly! It clunks down through the gears like a Harley I once had.

Thanks for the help and RIDE ON!

ThermionicScott 

Always good to hear the rest of the story!

02Giant 

I did this with my last steel frame build, works like a charm.
I cold set the stays, paralleled the dropouts, and used a spare wheel to align the hanger. Shifting is so smooth.

rydabent

No doubt the rear dropout or RD is bent.