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Derailleur swap - options for old ATB

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Derailleur swap - options for old ATB

Old 11-13-18, 11:12 AM
  #1  
Charliekeet
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Derailleur swap - options for old ATB

Picked up a 1989 Diamondback Ascent in a swap recently. Itís the one with the ďiridescent lilac smokeĒ paint job, which rules. But I digress...The only major issue I can see is that the rear derailleur (Shimano Exage Mountain, 6-speed) is broken: the cage arms were split apart, with the upper jockey wheel missing [guide pulley? Is that the right term?] entirely. It does screw back together at the pivot bolt where the wheel would be, though, just a missing wheel and maybe a washer-type piece that would go on the back of the wheel. Iím trying to work with what I have to replace it, since I assume itís not worth buying a guide wheel for this specific RD as Iím 0% concerned with restoring this to exact period spec, just to a well-functioning level.

What I have on hand for working derailleurs is:
1. Shimano RD-MC30 (90s STX I believe- lettering worn off) - I think was 7-spd?

2. Shimano RD-TX35 (Tourney, newer than the other one) - I think was 7-spd?

3. Shimano SIS something or other from sort of Ross 80s mtb, definitely 6-speed

Do either of the first two work completely normally with a 6-speed cassette? The STX certainly feels nicer. The old one I really donít want to spend the time cleaning.
Thanks for any help confirming, thoughts.
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Old 11-13-18, 11:18 AM
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If your RD shifter is friction rather than indexex, than any of the RDs should work.
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Old 11-13-18, 11:26 AM
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I am using an older 600 RD (6 speed) with an 8 speed indexed setup and it works fine. I suspect any of those will work as long as your shifters match the cassette. Or as stated above, you can always switch to friction.
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Old 11-13-18, 12:19 PM
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Originally Posted by oddjob2 View Post
If your RD shifter is friction rather than indexex, than any of the RDs should work.
Its a thumb shifter and is indexed, but I think it also has a lever that may switch to friction. Iíll check later.
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Old 11-13-18, 03:33 PM
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Any non-Dura Ace, non-Shadow SIS derailleur will work.

(and 7700-7800 DA will work)

https://www.sheldonbrown.com/dura-ace.html

97% of Shimano derailleurs made in the past 32 or so years will work fine.
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Old 11-13-18, 04:46 PM
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Good news. Thanks to all for the info & reassurance. Iíll try on that STX & proceed.
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