.21 mm’s can cause a lot of frustration!

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srshultz

Active Member
I bought a used Dura Ace, 10 speed cassette for my Cannondale Six/13 and installed it immediately. After adjusting the rear derailleur for a few minutes, I was having a sloppy 4 to 5 cog up shift. Down shift was fine. Took a 40 mile ride and made several small cable tension adjustments but couldn’t get the right shifts between 4 and 5. At home, I tore it apart and carefully checked each gear for warp and damage. No issues.

Reassembled the bike and still had the same issue. Another ride to test it. No good. Took it all apart again and still couldn’t find anything obvious. While reassembling the cassette I laid in the 5 gear and picked up the spacer and it felt a bit different. Out comes the micrometer and the measurement was 2.56! 10 speed spacers are 2.35. 2.56 is a 9 speed spacer. Put in the correct spacer and problem solved.

I may be the only one on the planet that has had this experience but if you have shift problems between just two cogs here is a probable cause.
 
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