? on moving FD when I swap standard double for compact double
08-22-12, 10:56 AM
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? on moving FD when I swap standard double for compact double
Ok,trying to setup a bike for a long racw with major climbing. Switching it to a compact double is one thing I am doing. I know I will need to drop the FD a tad. Can that be done without messing with the cable? Seems like the answer should be yes but I am not sure. And how do I check chain length to see is I need to shorten it? Will continue to run the same 11-25 cassette in the rear I think although I am considering a 12-27. thanks!
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08-22-12, 11:28 AM
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I know I will need to drop the FD a tad. Can that be done without messing with the cable?
08-22-12, 02:06 PM
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The radial difference between a typical 53T big ring and a compact 50T big ring is 5.8 mm or about 1/4". So if you don't lower your front derailleur it will be that distance too high, which is quite a bit. It will probably shift, but not very well.
08-22-12, 02:28 PM
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With the chain on the smallest chainring and smallest cassette cog there should be no slack in the chain. The rear derailleur should not be at the limit of its travel, the derailleur spring should continue to take all slack out of the chain.
If the chain is now long enough to handle the 53 - 25 combination, reducing the big ring size from a 53 to a 50 the chain will be long enough to handle the 50-27 combination. You should always check to see that the chain can shift smoothly onto any big to big combination.
I agree with the above that the derailleur should be lowered to where it is barely above the big chainring. With the front shifter in its lowest position and the barrel adjuster turned all the way down you will need to remove all slack from the cable and re-tighten the fixing bolt with the cable carefully positioned on the FD.
If the chain is now long enough to handle the 53 - 25 combination, reducing the big ring size from a 53 to a 50 the chain will be long enough to handle the 50-27 combination. You should always check to see that the chain can shift smoothly onto any big to big combination.
I agree with the above that the derailleur should be lowered to where it is barely above the big chainring. With the front shifter in its lowest position and the barrel adjuster turned all the way down you will need to remove all slack from the cable and re-tighten the fixing bolt with the cable carefully positioned on the FD.
08-22-12, 06:14 PM
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I would see how it shifts without lowering it first.
Sometimes they shift just great and sometimes not.
IF you don't have to lower it, it would make things MUCH simpler if you want to swap the existing crank back on.
"Technically", the Compact probably specifies a different FDER too. since the small ring is even "more" smaller than the large.
Give it a try without changing anything first.
Sometimes they shift just great and sometimes not.
IF you don't have to lower it, it would make things MUCH simpler if you want to swap the existing crank back on.
"Technically", the Compact probably specifies a different FDER too. since the small ring is even "more" smaller than the large.
Give it a try without changing anything first.
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