Rear derailleur will not shift to high gear

[acs5166]

I have a DuraAce rear derailleur (RD-7800) and a Ultegra 10-speed cassette on a Jamis frame with Easton EA90SL wheels. The derailleur will not adjust to the high gear even with the cable disconnected and the high adjust fully out.

The chain stops at the second highest gear. There are no spacers between the cassette and the hub. I tried a Mavic rear wheel to see if the spacing might be different and it had the same issue.

Any ideas why the rear derailleur won't come out more?

Thanks - Jack

[cyclerUK]

Has it worked O.K. before?
Has something been changed?

Check the hanger isn't bent or derailleur isn't damaged.
Has something (a stone) got inside the parallelogram?

[acs5166]

(07-11-2010, 04:19 AM)cyclerUK Wrote:  Has it worked O.K. before?
Has something been changed?

Check the hanger isn't bent or derailleur isn't damaged.
Has something (a stone) got inside the parallelogram?

No, it has never worked. I assembled the bike using a new frame. The hanger looks straight. The derailleur was from Ebay and supposedly new - although I can't verify that except it was clean. I've been riding it this way for a few months and have now become frustrated enough to try to fix it.

BUT - I think you just solved my problem!!! I checked to see if there was anything sticking or obstructing inside the parallelogram just now and I noticed a wear mark on the bottom side where the tab of the washer that compresses the cable has been hitting. I had it turned 90 degrees off. If you look at the Shimano instructions there is a big circle with an cross through it warning not to position it like I had it.

THANKS!!! I can't believe I missed this.

--- Jack