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Old 04-22-09, 04:20 PM   #1
longhaur
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Changing from a 3 ring to a 2 ring Crankset. Do I need to buy new Shift Levers?

Currently have FSA 3 ring crankset and going to a Sram 2 ring. Local bike store states I need to buy a new front derailleur, and shift levers since the old 105's were for the 3 ring crankset. I was thinking I might have to buy the front derailleur but do not want to change the shift levers due to the major cost.

Please, any advise on this issue will help.
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Old 04-22-09, 04:23 PM   #2
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They're wrong on both counts. While triple cranks (3 rings) can be finnicky with indexed shifting for STI levers, and you need to worry about compability, most front derailers can be set up to shift well enough on a double crank with STI levers. And if you're using down-tube or bar-end shifters, that discussion is moot anyway.

Are they trying to rip you off or just stupid?
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Old 04-22-09, 05:31 PM   #3
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You can set up your derailer and shifter to work with a double crankset. The end point adjustments on the derailer will take care of it, then you just use the 1 and 2 positions of your shifter.
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Old 04-22-09, 05:37 PM   #4
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All 105 shifters are double/triple compatible, in fact they are the same part number.
As to the front derailleur, it's probably worth trying the old derailleur. The instructions for setting up a double shifter are the same as for a triple shifter. Good instructions can be found at http://wwwparktool.com, and they are the same as Shimano's instructions.

Al
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Old 04-22-09, 05:46 PM   #5
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How many cogs do you have on the back?

Shimano 9-speed STI shifters are rated for either double or triple cranksets. They have different part numbers for 8-speed and 10-speed STIs.
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Old 04-22-09, 05:53 PM   #6
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Originally Posted by Retro Grouch View Post
How many cogs do you have on the back?

Shimano 9-speed STI shifters are rated for either double or triple cranksets. They have different part numbers for 8-speed and 10-speed STIs.
That's a good point but he seems to be saying that he wants to stay with the old shifters and change only the crankset. That should work with the possible exception that the front derailleur will be less than ideal.
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Old 04-23-09, 11:28 AM   #7
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A triple FD on a double crank less than ideal?

moved
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Old 04-23-09, 04:31 PM   #8
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Originally Posted by timcupery View Post
They're wrong on both counts. While triple cranks (3 rings) can be finnicky with indexed shifting for STI levers, and you need to worry about compability, most front derailers can be set up to shift well enough on a double crank with STI levers. And if you're using down-tube or bar-end shifters, that discussion is moot anyway.

Are they trying to rip you off or just stupid?
+1

Usually the problem is going from a double to a triple. A triple requires more travel in the front derailleur and in the amount of cable the shifters pull.

You'll have to set the limiting screws differently for the double, and you'll have to master the art of front derailleur adjustment, but it should work okay with what you have.
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