Bicycle Mechanics - Front Derailleur Capacity

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Yan
03-21-09, 08:28 PM
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?

Panthers007
03-21-09, 09:44 PM
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.
AEO
03-21-09, 10:05 PM
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

adriano
06-16-09, 11:06 AM
do you think i could push a ten speed double front derailleur between 18 teeth?
AEO
06-16-09, 11:33 AM
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.
Al1943
06-16-09, 11:37 AM
A 24t chainring seems awfully small.
10 Wheels
06-16-09, 11:39 AM
Mine works Fine.
50-39-24, with a 14-25 cassette.
demoncyclist
06-16-09, 11:39 AM
For loaded touring, a 24T granny ring makes sense.