# 7 speed STX-RC rear derailleur help



## javguy (Mar 16, 2007)

My rear derailleur has little spring tension on the lower pulley. I'm debating trying to disassemble it and try to rotate another twist into the spring to increase the tension or replace it. I can't find any STX-RCs anywhere and I may not be able to try my repair. Anybody know where I can get a 7 speed rear STX-RC derailleur? If I can't repair it, then I'll have to upgrade. I'm trying to learn whether other derailleurs will be compatible with my 7 speed cassette or whether I'll have to get an 8 or 9 speed cassette and new derailleur. If I have to do the latter, will I have to replace my hub or just dish my wheel a bit to adjust to the wider cassette? Are the 8 or 9 speed cassettes wide enough to cause significant/problematic stress on my 1994 Haro Escape frame that I have to worry about it breaking?


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## crisillo (Jul 3, 2004)

other Shimano derailleurs should work fine (8-9 speed), since the shifter is the one that determines how much it should move/how many gears (given the same cable pull ratio, which is the same for all shimano shfting gear so far)


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## donalson (Apr 13, 2004)

stx-rc was a 7/8 speed... i still have mine from the time i trashed the stx on my '95 bike back in the day... the shifter controls weather it is a 7 or 8 speed... 

don't know about going to 8spd cassette for sure but i've read the 7 speeds had a spacer in them so remove the spacer and you can use the 8 spd... which means it may also be 9 spd compatable... 

all that being said... you shouldn't have a problem finding an older 7/8 speed bits... 

i'm sure somone else will chime in... 
good luck man
mark


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## FrankinMich (Dec 17, 2005)

*Don't over complicate things*



javguy said:


> My rear derailleur has little spring tension on the lower pulley. I'm debating trying to disassemble it and try to rotate another twist into the spring to increase the tension or replace it. I can't find any STX-RCs anywhere and I may not be able to try my repair. Anybody know where I can get a 7 speed rear STX-RC derailleur? If I can't repair it, then I'll have to upgrade. I'm trying to learn whether other derailleurs will be compatible with my 7 speed cassette or whether I'll have to get an 8 or 9 speed cassette and new derailleur. If I have to do the latter, will I have to replace my hub or just dish my wheel a bit to adjust to the wider cassette? Are the 8 or 9 speed cassettes wide enough to cause significant/problematic stress on my 1994 Haro Escape frame that I have to worry about it breaking?


A derailleur is essentially a 'dumb' device that moves where the shifter tells it to go. I replaced an old 7 speed Alivio rear derailleur with an LX level "9 speed" derailleur and had no problems. If you want to upgrade to an 8 or 9 speed system, you will need new shifters, a new rear hub/wheel, a new cassette, and a new chain. As long as your rear drop out spacing is 130 mm, the 8 or 9 speed drivetrain should work fine.


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## javguy (Mar 16, 2007)

What about cage length? Does this matter for my application?


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## FrankinMich (Dec 17, 2005)

*Cage length*

As I recall, most seven speed cassettes topped out with something around an 11-28T configuration. Modern 9 speed, long cage derailleurs can handle up to an 11-34T when running a typical MTB triple chain ring (44-32-22T). You could probably get away with a medium cage rear derailleur, but they are hard to find. Do not use a short cage derailleur unless you are running a double chain ring crank (i.e. no big chain ring).


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## logbiter (Dec 30, 2003)

javguy said:


> What about cage length? Does this matter for my application?


short cage will work fine, if you're careful to not cross chain (big chainring-big cog/small-small). I prefer short/med cages for their snappier shifting.


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## crisillo (Jul 3, 2004)

logbiter said:


> short cage will work fine, if you're careful to not cross chain (big chainring-big cog/small-small). I prefer short/med cages for their snappier shifting.


I agree on the med cage (GS in Shimano speak)...a real short cage (like the Sram short cage or the one in the new Saint (SS), will not be able to take the slack)


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## ssbn742 (Feb 7, 2005)

PM sent.


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