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Compatability between 7 spd and 9 spd...(3 posts)

Compatability between 7 spd and 9 spd...spdplayr
Nov 30, 2001 9:00 AM
I am currently sporting a 7 speed crank and rings but I am installing 9 spd sti shifters and rear der. Will it work (yes i already have 9 speed wheels,cassette, and chain)? I've already done the 8 spd crank and 9 spd upgrade on my Mtn bike with no prob.

What about this? I also have a 7 spd front der on the bike now. What's the input on these issues.

This is for my commuter/ rainy day/on the trainer bike so i am trying to keep cost down.
Thanks in advance!
It'll workgrzy
Nov 30, 2001 10:27 AM
But not that well. the culprit will be the narrow 9 speed chain and the wider spacing between the 7 speed chainrings. Some say using a 9 speed inner chainring will close the gap and give you better shifting. You may never get the 7 speed front der to work very well at all due to the wide spacing of the cage. A 9 Sp front der. is a pretty inexpensive item. Since you've already done this on your MTB you pretty much know what to expect - it certainly won't be any worse thatn this. The only real difference between 8 and 7 speed, besides the extra cog, is the width of the rear cogset and the required dishing. You could find yourself fighting a little bit of a chainline issue whihc can really have an impact on shifting performance. Try it and if worse comes to worse buy the few select components to get the improvements you want.
re:front derailerRusty Coggs
Nov 30, 2001 5:40 PM
.....may be totally incompatible with STI. If the arm the cable attaches to is perpindicular to the derailer cage, it may be. If it isn't , it just won't be.