105 mismatched drivechain comparability

fuzzdog Posts: 196
I'm planning on putting my broken 105 right hydro shifter to good use by running it solo as just a shifter on my turbo trainer.
The hydro brake element of the shifter is caput because of a bleeding catastrophe but the shifting works perfectly so my idea is to have a dedicated setup using minimal spare parts on the smart trainer. So obviously I don't need brakes and since I rarely use the big ring on the turbo because of riding mountains I can get by without the front mech too. So it seems like a good way of making use if an otherwise perfectly servicable parts.
The question is will my 11 speed shifter work okay with a 10 speed rear mech?
I know about different cable pull between 10 and 11 speed but I assume that is with regard to the difference in spacing with 10 and 11speed cassettes. However, if I run 11speed shifter with 10 speed mech and 11speed cassette then will that work,all be it without shifting into either the top or bottom cog depending on how I set it up?
So just to confirm. That is.....
11speed 105 hydro shifter, 10 speed 105 rear mech (the older type) with 11 speed cassette.
Will it work?
With only 10 speeds obviously.


  • First.Aspect
    First.Aspect Posts: 14,622
    Yes probably, I ran something similar for a while. Worst case is buy a cheap 11-sp mech if it doesn't.
  • MattFalle
    MattFalle Posts: 11,644
    can't see why not - the mech only moves as far as the shifter wants it to.

    give it a bash and see what happens.
    The camera down the willy isn't anything like as bad as it sounds.
  • darkhairedlord
    darkhairedlord Posts: 7,180
    I don't think so.
  • First.Aspect
    First.Aspect Posts: 14,622
    It will depend how old the 10 speed derailleur is. If it's as old as when 10 speed came out it will have a different pull ratio. It it's more recent, it might be okay.

    I think.
  • whyamihere
    whyamihere Posts: 7,700
    If it's a Tiagra 4700 rear mech it will work because that groupset uses the 11 speed pull ratio for some reason, otherwise it won't. You might get a few gears to work, but it won't shift smoothly across the range. That might be ok for what you want it for on the smart trainer, if not then you'll need an 11 speed rear mech.
  • First.Aspect
    First.Aspect Posts: 14,622
    Used to be possible to slightly hack the pull ratio to get a better range of shifting.


    See the "position A, position B and position C" diagrams here. I think C might help. New pull ratio is 1.4, old 1.7, which is slightly too much.
  • fuzzdog
    fuzzdog Posts: 196
    Hello. Thanks for your answers so far.
    The rear mech is a 105 5701 type
  • wongataa
    wongataa Posts: 1,001
    It won't work well due to different cable pull ratios between shifter and mech.