Road Mech on an MTB

glentressmonster
glentressmonster Posts: 26
edited September 2012 in MTB general
Back in the early 90s when I rode a fully rigid Rockhopper with a Biopace chainset (for those of you who remember them :wink: ) me and my mate fitted road rear mechs to our bikes. I think I had an Ultegra. They shifted way faster and crisper than the old MTB mechs of the day. Plus they were much lighter.

I have recently converted to a 2x9 setup and my rear mech is starting to get quite worn. I'm considering a short-cage mech to increase chain tension to make shifting nice and fast. Has anyone tried fitting a road mech? If so, what was the outcome?

Comments

  • benpinnick
    benpinnick Posts: 4,148
    Roadie mechs that are 9speed are still compatible, and as long as you have enough teeth in the cage length, it should work fine. That said, the short cage MTB ones are as short as most 2x9 setups can go, so probably a medium cage roadie mech required, and so no real point.
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  • nicklouse
    nicklouse Posts: 50,675
    glentressmonster wrote:
    . Has anyone tried fitting a road mech?
    you have and it worked and nothing has really changed.

    what has changed is everything has is some way improved.

    contry to popular belive a short cage mech does not improve shifting. a set up mech does though.

    10spd road mech have the same pull as 9spd kit.
    but TBH you would doe better fitting a suitable MTB 9spd mech.

    i remember upgrading my MTB to the Exage groupset with Biopace cranks.
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  • glentressmonster
    glentressmonster Posts: 26
    Surely, Nicklouse, a shorter cage = shorter chain, which ought to mean better shifting performance because it does not need such a heavy spring to keep the tension on the chain?
  • RevellRider
    RevellRider Posts: 1,794
    Using a short cage road mech to get better shifting on a 2x9 set up won't work. Something like an Ultegra rear mech is designed for a 28 tooth maximum on the rear cassette. Most 9 speed mtb cassette are 32 or 34 tooth, meaning that you have to adjust the B Stop screw all the way in to get it to clear. Compromising the shifting at the lower end of the cassette.

    Also, a short cage mech has a smaller capacity on the tooth difference. So if the OP is running an 11/34 cassette and a chainring difference of greater than 10 tooth the mech won't shift as well as it's designed to.

    Just buy a mid cage MTB mech. The Shadow technology on current generation Shimano mechs is fantastic
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  • YeehaaMcgee
    YeehaaMcgee Posts: 5,740
    glentressmonster wrote:
    Surely, Nicklouse, a shorter cage = shorter chain, which ought to mean better shifting performance because it does not need such a heavy spring to keep the tension on the chain?
    Nope, not at all. You still measure the chain the same way - and when you measure the chain, the rear mech is not part of the equation, at all.
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  • ilovedirt
    ilovedirt Posts: 5,798
    That and he needs a medium cage, a short cage won't be long enough.
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  • felix.london
    felix.london Posts: 4,067
    nicklouse wrote:

    i remember upgrading my MTB to the Exage groupset with Biopace cranks.

    My Ridgeback came with Exage and Biopace rings...mmmm..toe clips
    "Why have that extra tooth if you're not using it?" - Brian Lopes

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  • willy b
    willy b Posts: 4,125
    Ran a shortcage Ultegra mech on my 1x9 setup, with a 36 up front, and a 11:32 to teh rear. All worked well for around 100 miles until Mountain Mayhem mud snapped the mech, as I had a spare MTB XT mech I just fitted that.

    1x9.jpg

    So yes it works, i'd say maybe not as strong as a MTB mech though?
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  • glentressmonster
    glentressmonster Posts: 26
    Thank you all for your advice and comments. It seems a medium or short cage MTB mech would be the ideal choice.

    I did the maths and a short cage mech would be right on the upper limit of a short cage road mech for my drivetrain so it would probably kill the spring.
  • nicklouse
    nicklouse Posts: 50,675
    glentressmonster wrote:
    Thank you all for your advice and comments. It seems a medium or short cage MTB mech would be the ideal choice.

    I did the maths and a short cage mech would be right on the upper limit of a short cage road mech for my drivetrain so it would probably kill the spring.
    So what is your range?

    And be very aware that not all SGS have the same range. Likewise not all GS have the same range.

    So work out what you and check the details n the makers webby.

    Or ask.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
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  • ilovedirt
    ilovedirt Posts: 5,798
    glentressmonster wrote:
    Thank you all for your advice and comments. It seems a medium or short cage MTB mech would be the ideal choice.
    You need a med cage, a short cage will not take up enough slack in the smaller rings.
    Production Privee Shan

    B'Twin Triban 5
  • njee20
    njee20 Posts: 9,613
    Except for Saint Shimano don't do short cage MTB mechs, so it's fairly irrelevant.

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