will a 3x10 speed front derailer work with an 3x8 speed?

kenlawrence
kenlawrence Posts: 17
edited January 2014 in MTB buying advice
Hi guys, I need to buy a new front derailer and just been looking on the chain reaction website and a lot of them seem to be 10 speed, does this just mean it will work with a maximum of ten gears at the rear or only 10 gears at the rear? And if it is 10 only, why is this? How does it know what's up the back?

Thank you!

Comments

  • benpinnick
    benpinnick Posts: 4,148
    It will work, but you'll probably lose a gear from the range you'd otherwise have (eg. On the granny ring you'd normal have 1-6 without rubbing, using a 10spd mech you'd probably only get 1-5) I wouldn't let this put you off though, it will still be perfectly usable.
    A Flock of Birds
    + some other bikes.
  • jimothy78
    jimothy78 Posts: 1,407
    The cage the chain passes through is narrower with 10 speed, and so although it will work, you'll get more rubbing. I have an old 6/7/8 speed (they all use the same width chain) derailleur in the garage you could have for a couple of quid. Will dig it out later and send you the details if you're interested.
  • kenlawrence
    kenlawrence Posts: 17
    Ok, so all my 8 gears will still work at the rear? or id loose a gear so only be able to use 7 up the back? And they might not be as smooth as they would be with a 8 speed front due to rubbing? Just want yo make sure I know what you mean as I'm very new to the biking scene and don't want to buy something that won't work properly, thanks,
  • kenlawrence
    kenlawrence Posts: 17
    Ok, so why is the cage narrower out of interest? Are ten speed chains thinner? And yes would be interested, basically my situation is some friends and I are cycling across Thailand in the summer so I'm in the throws of getting a Bike I bought second hand up to scratch as it needs to be working very well as Bike shops are going to be very very few and far between. I wouldn't be against a second hand one but do you think it might be safer with a new one given my situation? Thanks
  • The Rookie
    The Rookie Posts: 27,812
    10 speed chains are narrower as the 10 speed cassette is the same overall width as an 8, the gears are closer together so the chain is narrower to make sure it only sits on one gear at a time!

    You can get away with a 9 speed, it is still slightly thinner than an 8, but works just fine.
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.

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