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Old 03-10-08, 09:08 AM   #1
DogBoy
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Crankset & Front Derailleur Compatibility

I've been mulling over the idea of upgrading from 7-sp to 9-sp. I already have an xt derailleur in the rear, so my thoughts are that I would simply need shifters/cable. I already have a cassette and a chain. Then I got to thinking about the crankset. The current crankset says for IG chains only. I believe it is designed to be compatible with 7-sp...so will the 9-sp chain be too narrow? Along the smae lines, will my nexus FD work with the narrower chain?

If I have to buy a new BB, Crankset, FD and shifters it is quite frankly not worth it to me.

Thanks.
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Old 03-10-08, 09:23 AM   #2
sch
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The likely result is that it will work with the crankset you have, depending
in part on how much mileage is already on the cranks. The teeth will be
a bit narrower after 3-6kmi such that the narrower chain is less likely to
be a problem than with a new 7spd CW. OTOH too much wear will cause
the chain to skip as most wear occurs between the teeth on the leading
edge. One speed differentials work best (7<->8) (8<->9) etc. The FD
should work ok as well, a little sloppier than before but should handle the
shifting.
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Old 03-10-08, 09:56 AM   #3
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You haven't said what you've got. If the shifters are indexed they'll need to be 9-speed Shimano.
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Old 03-10-08, 11:12 AM   #4
DogBoy
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I was planning on replacing the shifters. I've got 7-sp XT index/friction shifters. I already knew they wouldn't work. The concern was with the FD and the crankset. I think the answer from sch is that I probably "should" change the crankset, which to me means I would, which also means this is no longer the quick and dirty upgrade that I wanted.

Thanks for the info!
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Old 03-10-08, 03:12 PM   #5
Bill Kapaun
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Is your current Free Hub body long enough for a 9 speed? 8 speed and above use a longer body than 7 speed, although you can use a 7 speed cassette on those with a spacer.
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