Phil Lefever

Hi all,

Here is a little niggle from my latest build. All components are brand new.

Bianchi Titanium XL frame
DA 7800-SS
DA 12/25 cassette
CN-7800 Chain

The issue is that the rear derailleur won't shift to the small cog (if I pull out on the cage I can force it sometimes). I have the high gear limit screw backed out fully and the cable is slack.

It strikes me that the hanger/dropout might be too thin (.260") not spacing the derailleur out far enough. The thought of shimming the derailleur mounting bolt has occurred to me. My other bikes have thicker hangers...

Anyone else seen this problem? How is it best resolved?

Thanks for any sage advice!

Phil

HillRider

Another possibility is to realign the rear hub by switching spacers to put the small cog further inboard. You could even reduce the wheel dish if you do it.

Quijibo187

Just another thought, is the derailer hangar bent in a bit? That would cause what you're experiencing too.

kgatwork

Check that the cable hold down is in the correct position on the derrailluer.

rm -rf

His cable is slack, so there must be some other problem.

Steve Katzman

You could realign the hub but you would make the wheel incompatible with other bikes. Also you would have to redish the wheel which would increase the wheel dish - not reduce it.

My guess is that the derailleur hanger is slightly bent. Get a tool on it and check for parallelism.

If that doesn't work, I don't see anything, in principle, wrong with using a thin spacer under the derailleur mounting bolt.

roadfix

^^^ +1 .....I vote for checking the hanger alignment first.

kgatwork

I had the same problem when I installed my DA rear derrailuer. I initially installed the DA rear correctly and when I added cable donuts, in inadvertantly installed the clamp the wrong way and as a result I could not get to the smallest cog. I adjusted it to try make up but to no avail until I inspected the clamping mechanism. The cable was slack but the cable clamping mechanism when installed incorrectly prevents the derrailuer from fully extending outwards.

Chances are he looked at the slack cable on the chainstay not between the rear derrailuer adjuster and the clamping mechanism.

HillRider

Baaah, your right! I don't know what I was thinking but respacing the cassette more inboard will indeed increase the required dish.

Phil Lefever

Thanks for all the help guys!

It appears that kgatwork wins the prize with the been-there-done-that-got-the-Tshirt experience.

The cable clamp on the derailleur has a tab bent up at 90 degrees. I had the tab oriented parallel with the wheel on the back side of the derailleur which fouls against the body preventing adequate outward travel to hit the high cog. With the tab orientated perpendicular to the wheel towards the rear of the derailleur (as shown in the manual! duh) it works fine business

Time for a little riding!

73 all

Phil

kgatwork

Thanks for the response, I was wondering if I was right. I'm glad it was that simple!

mrteddiamond

Hmm -- I've been having a similar problem -- never would have thought to check derailleur clamp. Props, kgatwork!!