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Old 03-21-09, 08:28 PM   #1
Yan 
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Front Derailleur Capacity

I'm building a 3x9 speed touring bike with 50-38-24 chainrings. The people in the touring forums recommend the 9 speed Tiagra front derailleur, because it has a comparatively wide cage that minimized chain rub.

My setup has a 26 tooth difference between the highest and lowest chainrings. Shimano's tech docs say that the Tiagra front derailleur has a 20 tooth capacity. Will it still work, and if not, what is a better front derailleur?
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Old 03-21-09, 09:44 PM   #2
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Shimano's Max Tooth Diff. crud is wildly inaccurate. It will likely work fine - but I never did this with a Tiagra. Done it with others in going over Shimano's stated MAX. No problems yet.
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Old 03-21-09, 10:05 PM   #3
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it should work fine, I have a 105 double FD pushing a 26-36-46 and there's plenty of space left in the cage for a 50-38-24
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Old 06-16-09, 11:06 AM   #4
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do you think i could push a ten speed double front derailleur between 18 teeth?
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Old 06-16-09, 11:33 AM   #5
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between two chainrings or three?

between three, you can exceed 20 teeth provided you don't go beyond 14~16T difference between each cog.
between two, the shifting can be really horrid simply due to the teeth difference.
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Old 06-16-09, 11:37 AM   #6
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A 24t chainring seems awfully small.
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Old 06-16-09, 11:39 AM   #7
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Mine works Fine.
50-39-24, with a 14-25 cassette.
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Old 06-16-09, 11:39 AM   #8
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For loaded touring, a 24T granny ring makes sense.
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