Bicycle Mechanics - Dura Ace 10sp rear derailleur - 11-23 issues

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PDA
Yoeri
08-27-07, 08:32 AM
Hi
yesterday I wanted to change my 12-25 to a 11-23 and I had troubles adjusting my rear derailleur so that that the chain would run smoothly on my 11. I tried everything up to adding/removing spacers (do you actually need spacers between your biggest cog and the wheel?).
It kept on bouncing up and down my 11 and regardless the adjustments I made on the derailleur it kept on doing the same. I changed it back to my 12-25 and no more troubles and it runs like butter....

wheelset: Zipp 404's (tubular)

Any thoughts what I do wrong?

Thanks!!

Yoeri
Hong Kong.

DMF
08-27-07, 10:27 AM
Did you use an 11T lockring? Or did you re-use the 12T lockring from the old cassette?
Yoeri
08-28-07, 09:23 AM
huh...there is a difference between the lockring for the 11 and the 12 cog set?
Might that be what caused it? what is the difference between them?

yoeri

zac
08-28-07, 09:30 AM
Yeah there is a difference in the lockring, but also your B setting will need to be adjusted.
mantis
08-28-07, 09:41 AM
Another possibility is the wrap around "tab" on the pressure plate that holds the cable in place under the hex screw. It can come income in contact with the derailleur swing arm and prevent the cage from moving over far enough to ceter over the smallest cog, regardless of the limit travel setting. It happened to me on my DA 7800 when I added a 1mm spacer between the wheel and cogs.

The fix is to simply rotate that pressure plate 90 degrees so the tab points aft and it will not interfere with the derailleur action.
DMF
08-28-07, 09:49 AM
11T lockring is smaller than 12T lockring. 12T lockring on an 11 will not let the chain seat fully on the teeth and it won't stay there.

On 9-speed the 11T has "11T" stamped on the face. The 12T has nothing (other than the "Shimano" etc..). Not sure about 10-speed but it's probably the same.

B-screw should be checked but isn't critical. I make this swap all the time without any readjustment.
Yoeri
08-28-07, 06:41 PM
Thanks guys for all the comments... first time I use bikeforums.net... but not the last time!

cheers
yoeri
Bob Dopolina
08-28-07, 08:22 PM
Definitely the lockring. Definitely. Yeah.
p4nh4ndle
08-28-07, 09:24 PM
Definitely the lockring. Definitely. Yeah.

http://photos1.blogger.com/blogger/2088/2881/1600/RainMan_28.jpg

definitely the lockring. definitely. yeah.