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Old 10-26-06, 03:28 AM   #1
cs1
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STI Compatible ft der

I was planning on moving an old Deore group to a road bike frame I have. Will this front der http://www.nashbar.com/profile.cfm?c...Shimano%20Sale Work with 7 sp STI? If not anyone know where I can source a 28.6 triple ft der? My crank has 46 tooth chainring. Most road ft der's I've seen specify somewhere in the 50-53 tooth range. Thanks

Tim
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Old 10-26-06, 05:16 AM   #2
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STI road shifters have a different ratio. The derailleur will try to move from the small ring almost all the way to the large ring on 1 click. I presently run a 105 front derailleur on a 48 tooth large ring and it works fine and might work with a 46. Otherwise you could look for a crankset in the 26, 36, 48 range.
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Old 10-26-06, 03:44 PM   #3
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Quote:
Originally Posted by maddmaxx
STI road shifters have a different ratio. The derailleur will try to move from the small ring almost all the way to the large ring on 1 click. I presently run a 105 front derailleur on a 48 tooth large ring and it works fine and might work with a 46. Otherwise you could look for a crankset in the 26, 36, 48 range.
Thanks, I know the ratio is different. I was looking for a der that could handle a 46 for 48 tooth chainring. The woods are full of one that can handle a 50 or 53. If I used barons, it would be a moot point.

Tim
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Old 10-26-06, 05:39 PM   #4
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Quote:
Originally Posted by cs1
Thanks, I know the ratio is different. I was looking for a der that could handle a 46 for 48 tooth chainring.
Tim
The bike I ride most these days has a 105 FD and 46 chainring. Not even the slightest problem.
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Old 10-27-06, 03:26 AM   #5
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The bike I ride most these days has a 105 FD and 46 chainring. Not even the slightest problem.
Are you using a triple or double. 105 ders are very affordable.

Tim
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Old 10-27-06, 11:58 AM   #6
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Originally Posted by cs1
Are you using a triple or double. 105 ders are very affordable.

Tim
I'm using the 105 double, with a 46/36 RSX double crankset. Can't say whether the triple version would work as well, but I don't know why it wouldn't.
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Old 10-27-06, 12:30 PM   #7
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I've run a 44*32*22 on two different bikes with a 105 FD and a Tiagra FD with STI. It took just a little bit of tuning, but no real problems. Yea, it looks sort of strange, the curve of the derailer doesn't come close to matching the curve of the chainring, but it's more than functional. Shifts UP the Crank aren't as smooth and slick as my Ultegra bike, but I've never had it fail.

Steve W.
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Old 10-28-06, 05:30 PM   #8
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I curently have 44*32*22 with Tiagra FD and 9 speed STI.

Shifting is fine, although I have to trim the FD while in middle chainring and inner/outermost sprockets. This is because the der' is about 5mm higher than it should due to the location of the seat tube bottle mount braze on.
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Old 10-29-06, 04:49 AM   #9
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Originally Posted by Sholto
I curently have 44*32*22 with Tiagra FD and 9 speed STI.

Shifting is fine, although I have to trim the FD while in middle chainring and inner/outermost sprockets. This is because the der' is about 5mm higher than it should due to the location of the seat tube bottle mount braze on.
I would imagine that a 46 or 48 tooth chainringe would put the der in a better position then. Thanks, Tiagra der's are very affordable.

Tim
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