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Old 06-08-07, 03:23 PM
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themetalman
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chain

i went from a 39/53 chain crank to a 34/50 do i need to remove some chain links....i have a long derailer inthe back because i run a 29 casset..
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Old 06-08-07, 03:28 PM
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If your derailleur can still wrap the chain in all useable gears without the chain rubbing on the bottom of the pulleys you don't "need" to, esp if you may go back to the original or go to a larger low end in the rear. Shifting may be marginally better with the chain properly sized but very minor diff. Always a minor risk in breaking a chain that is working fine.
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Old 06-08-07, 03:55 PM
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Originally Posted by themetalman
.i have a long derailer inthe back because i run a 29 casset..
The length of the dérailleur arm (cage) has nothing to do with the size of the cassette rings. If you paid for it when putting on a larger cassette, then you wasted money.
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Old 06-08-07, 04:05 PM
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Originally Posted by DMF
The length of the dérailleur arm (cage) has nothing to do with the size of the cassette rings. If you paid for it when putting on a larger cassette, then you wasted money.
Applesauce
Originally Posted by Sheldon_Brown
Derailers come in long, medium and short cage versions. Shimano designates them: SGS (long), GS (medium), and SS (short.) The short cage ("road") ones only work with narrow range ("road") cassettes, because they don't have enough capacity to take up chain slack for use with a wide range cassette. Short and medium cage derailers are also limited in terms of the largest rear sprocket that they can clear without having the jockey pulley rub on the sprocket. Generally, SS & GS rear derailers won't work properly with rear sprockets larger than 30 teeth.

Long-cage (SGS) derailers have greater takeup capacity, and work with all types of cassettes. Long-cage derailers are commonly called "mountain" derailers currently, though in the past, this style of derailer was known as a "touring" derailer. (The marketeers retired the use of "touring" as a buzzword in the late '80s when mountain bikes became the hot item.)
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Old 06-08-07, 07:11 PM
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Originally Posted by themetalman
i went from a 39/53 chain crank to a 34/50 do i need to remove some chain links....i have a long derailer inthe back because i run a 29 casset..

On the smaller chainring you've lost 5 teeth over the whole circumference of the sprocket, considering the chain is wrapped around roughly half the sprocket this is a loss of on 2.5 teeth for the chain wrap or 1.25". However on the larger sprocket you've only dropped down 3 teeth or 1.5 teeth for the chain wrap so when in the larger ring the chain would only be long by 3/4". Since the chain can't be shortened by this amount, leave it as it is as the deraileur should take up this difference.

The above only holds true as long as the chain length was at a reasonable length to begin with on the larger rings (39/53). If the chain was on the limit of being on the short or long side, then there's room for adjustment on the chain length.

Originally Posted by cny-bikeman
If your derailleur can still wrap the chain in all useable gears without the chain rubbing on the bottom of the pulleys you don't "need" to, esp if you may go back to the original or go to a larger low end in the rear. Shifting may be marginally better with the chain properly sized but very minor diff. Always a minor risk in breaking a chain that is working fine.
This is the best solution. Use the chain as is and run the bike through the gears before deciding to shorten the chain.

Last edited by ryder47; 06-08-07 at 08:25 PM.
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