9 Speed Front Derailleur on 8 Speed Drivetrain?

morxy
morxy Posts: 114
edited March 2009 in Workshop
Can I fit a 9 speed front derailleur to my 8 speed drivetrain? I'm just worried the derailleur cage may be too narrow because 9 speed chains are narrower than 8 speed.

What I really want is a 31.8mm band on 8sp front derailleur. But I can't find them anywhere :(

Comments

  • maddog 2
    maddog 2 Posts: 8,114
    I think they are a tad narrower. More of an issue on triples than doubles. You could always run a 9spd chain. That will work okay on a 8spd cassette and free you up to fit a 9spd front mech.
    Facts are meaningless, you can use facts to prove anything that's remotely true! - Homer
  • topdude
    topdude Posts: 1,557
    Hi, it will work ok but the chain might rub on the cage if running on the outer extremes of the cassette.
    He is not the messiah, he is a very naughty boy !!
  • andy_wrx
    andy_wrx Posts: 3,396
    I run a 9sp Ultegra front derailleur on my 8sp TT bike.

    It does seem to need a fair bit of trimming as I move up and down the block, but then I'm running bar-end shifters, the front not indexed and it's no problem.
  • John.T
    John.T Posts: 3,698
  • morxy
    morxy Posts: 114
    I already get slight chain rub on the inside of my derailleur cage btw. So, who knows, maybe I already have a 9 speed derailleur! (Wouldn't surprise me as the bike initially had brake cable attached to the rear mech etc. :roll:)

    Luckily the rubbing's only noticeable in exteme gears though, and I can minimize that with trimming, so it's okay. It's a double, incidentally - 39/53.

    I ended up buying an 8-speed Sora mech with a braze on fitting from wiggle. Couldn't find any band ons. Will get that adapter too. Cheers.