Bicycle Mechanics - Do I need a new rear derailer if I switch to 9 speed cassette (was 7)?

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tonyc
07-10-04, 11:04 AM
Hi, do I need to buy a new rear derailer if I plan to go with a 9 speed cassette/chain and my bike originally was built for 7 speeds?

Thanks

Retro Grouch
07-10-04, 12:26 PM
Hi, do I need to buy a new rear derailer if I plan to go with a 9 speed cassette/chain and my bike originally was built for 7 speeds?

Thanks

No but you might have to get a new front derailleur. The rear derailleur guides the chain from the middle. The front guides the chain from the sides. The nine speed front derailleur has a cage that's just a touch narrower than previous ones. I've found it necessary to use a nine speed front derailleur with a triple crankset, but I'm told it isn't always necessary with a double crankset.
John E
07-10-04, 02:11 PM
First try out the new chain, cogset, and index shifter with your old rings and derailleurs. You may be pleasantly surprised.

pogoman
07-12-04, 12:30 PM
You may also want to look into your frame. My bike was originally for a 6 speed cassette and could be upgraded to 7 however, the frame won't fit a 9 or 10 cassete. at least that's what the mechanic said.
Seaners
07-13-04, 05:36 PM
you'll want to swap out the pulley wheels in your rear derailleur as the 7 speed ones are wider than 9speed (and 8speed) and aren't strictly speaking suitable for nine-speed chains.
DieselDan
07-13-04, 07:55 PM
Check your freehub. 8/9 speed freehubs are wider then 7 speed.