Source
r/bikewrench•
commentor2

Poor shifting despite new components

EDIT: thanks everyone. So the derailleur hanger was a little out of alignment. I fixed that and adjusted the B-tension to close the gap between the top jockey wheel and the cogs and it is much better, at least on the repair stand.

Original post: I have an Ultegra 6700 bike with about 3000 miles and have just replaced pretty much everything except the rear derailleur: shifter, cable and housing, chain, cassette.

No matter what I do with the cable tension, rear shifting is poor. It sounds and feels good once in a particular gear but going between cogs often requires over-shifting then going back. I have a newer bike with 105 that is much better. Is it possible the derailleur has worn out?

Posted Nov 16, 2017, 2:42 PM UTC · edited

1222
huntthequiet•

A need for over-shift normally means one of two things:

  • bad cable/housing quality including excess friction in the cables (especially so with Shimano 10-speed, which is more sensitive to cable quality than any other system because it pulls less cable per shift), or
  • the upper pulley is too far from the cassette, thereby preventing the derailleur from getting the sharp chain angle needed for smart shifting. Usually this can be fixed by B-tension adjustment.
17
valgonzarp•

I used to get it a lot until I noticed my jockey wheels are totally ruined

2
pigcupid•

7900/6700/5700 have notoriously poor shifting, but it can be improved with some tricks. Once you follow all the other advice here (make sure your hanger is straight, etc.), then I suggest you take a look at the cables and housing.

When this series was new, Shimano specced a PTFE-coated shift cable and housing which was included only one nylon ferrule, while the rest were CNCed aluminum. This was designed to aid in the shifting by reducing the friction from the lever and stiffening the shifts at the frame, but even this didn't help too much. After 9000 came out, and Shimano introduced their polymer cables (Shimano SP41 housing didn't change), I began putting these new cables on the previous generation of Shimano shifters, and I found this and a very clean routing of the housing (often crossing them in front of the headtube, so that the cables crossed again on the downtube) made a huge difference, that often means this generation of Shimano can shift beautifully.

tl;dr - Use slick cables, and good housing with very clean bends. Shimano has trickled it all the way down the line to budget Optislik Cables, while other manufacturers like Jagwire responded with their own Teflon cables, and now their new high-polish stainless steel cable (which which I have no experience).

11
ride_whenever•

For reference, the jagwire high-polish shit all over any other cables.

Better than the polymer cables by a mile.

2
pigcupid•

Noted! I was looking at ordering some for when I re-cable my bike. Do you know the difference between the Pro-Polished and the Ultra-Slick?

1
ride_whenever•

The ultra are what I use, they’re the first uncoated cable that feels as smooth as the coated shimano ones, with none of the coating issues.

1
commentor2OP•

This stuff?

http://jagwire.com/products/diy-cable-kits/2017road-elite-link-shift-kit

1
ride_whenever•

The first one here

The link kit is amazing, like proper amazing, but soooooooo expensive.

2
commentor2OP•

Thanks, I did use SP41 for the new cables/housing.

1
D0rk4L•

Highly unlikely it's the derailleur, unless it's bent. Have you checked the derailleur hanger alignment?

7
commentor2OP•

No but I should do that. Excuse to buy another tool!

3
D0rk4L•

Another thing to consider. Did you do the cables/housing yourself? A common issue is not cleaning up the ends of the housing. Filing them flat and making sure the inner sheath is re-opened after being cut. Those can both add drag to the cable which will inhibit shifting.

2
commentor2OP•

Yeah, I did them myself with a Dremel and deburred and cleaned up the ends of the cut housing. It seemed pretty smooth when I installed.

3
Trouterspayce•

Was also going to suggest checking the derailleur hanger. Can easily go out of whack if your bike falls over on the drive side, or especially if you have a crash.

1
Ride_at_Dawn•

Does your cassette have the same amount of sprockets as your previous one?

1
commentor2OP•

Yup, CS-6700 just like the original.

1
Drxgue•

Right, but CS-6700 comes in different ranges. Do the ranges match?

1
commentor2OP•

Yes, the same range as well

1
TML_SUCK•

The shifter is a 6700 10 speed shifter? Is the derailleur hanger bent? Any kinks or tight bends in the cable housing?

1
commentor2OP•

Yup, same model shifter. Cable housing is installed pretty well I think. Someone else suggested derailleur hanger as well and that seems like a good idea.

1
texastoasty•

Check condition of jockey wheels and tightness of the fastener

1
manys•

It still sounds like too-tight cable to me.

0