twist gripshift on road mech?

JOHN4537
JOHN4537 Posts: 34
edited January 2010 in Workshop
Hi.

I'm converting a hack mountain bike to use an 8 speed Sram or Shimano road mech. Can anyone advise whether the 8 speed twist grip shifters i have will still pull the rear derailuer on a road mech the same distance as the mountain cassette i am replacing? I am hoping i don't need to change the gear shifters.

Many Thanks

Comments

  • John.T
    John.T Posts: 3,698
    Shimano rear mech. Yes. The pull ratio is the same as MTB. Most SRAM ones are different. Even their road and MTB mech use different pull.
    My Fleet.
  • JOHN4537
    JOHN4537 Posts: 34
    Thanks John.T.
    What I was worried about was indexing. (Was at work on the original question and short of time to explain it better.)
    The plan is to make an old decathlon Rockrider 26in mountain bike alloy frame into a fast training-come-short comute bike using 700C wheels, Carbon road fork, Tiagra rear mech, No front mech - single 48t crank. But i'm fitting it up using drops that have a split to fit a griptwist rear shifter. Just using simple road brake levers, no STI stuff. I was just worried the indexing wouldn't work as this grip shifter was driving a mountainbike 8 spreed cassette previously. Keeping it light n' fast.

    Can anyone forsee any problems I may have regarding the gear/shifting. thanks :)
  • ynyswen24
    ynyswen24 Posts: 703
    It's the SRAM X series mech/shifters that use the same 1:1 cable pull as the SRAM road kit, you can't mix and match with Shimano. The SRAM Gripshift shifters are designed to work with Shimano rear mechs, these will be fine with any Shimano mech - road or mtb.
  • gundersen
    gundersen Posts: 586
    If I remember right then there are 2 gripshift types.
    The ESP type that I have on my Kona - it is 1 to 1
    Then the other which is Shimano compatible - I think they are called attack or something similar

    You might be lucky to find some of the origional gripshifts that were designed for racers before the MTB days.
  • JOHN4537
    JOHN4537 Posts: 34
    Thanks for your input chaps. It seems that this will work.

    i have just taken the twistgrip shifter off a mountain bike and detached the gear wire onto my Carrera virtuso roady. (I hate taking her apart but had to try it :o )

    Wired the twistgrip through to the rear mech (sora 8) and tuned it up until it started shifting reasonably well. Took a while. Unable to road test cos of the weather outside (7 inches snow/ice) but an insitue test seems to work ok. I'll know more when i do a running test under load but happy so far.

    Now to go out and get the rest of the bits for the bike build.

    cheers all

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