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5700 RD

Shimano say the smallest large sprocket when using this RD should be 25... anyone run a 23 cassette successfully? Asking for a friend of course

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  • First.AspectFirst.Aspect Posts: 6,691
    Your knees have got to last you the rest of your life Ugo.
  • MattFalleMattFalle Posts: 5,059
    I have no idea but as a genuine question, why should there a limit to the smallest large sprocket?

    this would mean you can't run 11-21 either...
  • First.AspectFirst.Aspect Posts: 6,691
    It is about the distance between the top jockey wheel and the cassette.

    Ha, Ugo you could just use an oversized jockey wheel. That you make you faster as well!
  • It does. Shifting marginally slower and maybe become a bit hesitiant more easily.
    www.thecycleclinic.co.uk
  • whyamiherewhyamihere Posts: 7,472
    It will have a similar effect to one of the hanger extenders like a Roadlink, but at the other end of the cassette, and probably not as extreme. They allow you to shift a to a larger cog but at the expense of shifting quality on the smaller cogs. Doing this, you'd need to set the B screw so that the mech is further from the largest sprocket than usual to make sure it's set correctly for the small ones.
  • MattFalleMattFalle Posts: 5,059
    So they've designed it so that - without changing jockey wheels, adding wolflinks, etc - you can't run a 23 or 21?
  • whyamiherewhyamihere Posts: 7,472
    MattFalle said:

    So they've designed it so that - without changing jockey wheels, adding wolflinks, etc - you can't run a 23 or 21?

    Pretty much, yes (or at least you can't run them with optimal shifting). The advantage you get is that you can run a larger (30t) large cog without needing something like a Roadlink. Shimano obviously decided that the people running 105 were likely to want lower gears rather than tighter cassettes.
  • MattFalleMattFalle Posts: 5,059
    Coolio - grazie.
  • ugo.santaluciaugo.santalucia Posts: 26,346
    The only reason I ask, is that I want a light cassette for Hill Climbing and Dura Ace are currently on offer half price as 11-23. I rarely need a bigger sprocket in a race...
  • MattFalleMattFalle Posts: 5,059
    Oohh - linkie?
  • ugo.santaluciaugo.santalucia Posts: 26,346
    Highonbikes or something... 79 pounds
  • MattFalleMattFalle Posts: 5,059
    top stuff - grazie!
  • MattFalleMattFalle Posts: 5,059
    At that price go for it dude - perfect for what you need, really good quality, good price.

    tbh, unless you live somewhere really hilly, a 23 is fine on any crankset.

    do it do it do it do it. do it now. do it. do it.
  • MattFalleMattFalle Posts: 5,059
    Just bought one to replace the ultegra one on the posh bike.

    now not only am i unfettered with the blandness of ultegra i've probably saved about 6 grammes......
  • ugo.santaluciaugo.santalucia Posts: 26,346
    I'm just concerned it might not want to shift on the 23, which would render it pointless during a race...
  • whyamiherewhyamihere Posts: 7,472
    If the B screw winds out far enough, you could set it nicely for the mid to high cogs and sacrifice the small ones, which you probably won't be using in a hill climb, but that depends on frame geometry as well. It's also not likely to be a massive issue, the shifting will be slower but will probably work.
  • ugo.santaluciaugo.santalucia Posts: 26,346
    Alright, I see if I can gather a bit of funds, after paying £ 500 to a structural engineer to design a couple of steel beams... :/
  • MattFalleMattFalle Posts: 5,059

    I'm just concerned it might not want to shift on the 23, which would render it pointless during a race...

    buy it

    try it but don't fcuk it

    if it doesn't work send it back
  • First.AspectFirst.Aspect Posts: 6,691

    Alright, I see if I can gather a bit of funds, after paying £ 500 to a structural engineer to design a couple of steel beams... :/

    I wasn't joking about the jockey wheels. Shimano's standard ones are 10t I think... might be 9... and you can get an 11 or 12 in there okay. I just put 12t Hope ones on a shimano rd and it is tight for the lower jockey wheel (nothing some pliers won't sort out) but runs fine. The difference in diameter will be greater than between a 23 and a 25.
  • ugo.santaluciaugo.santalucia Posts: 26,346

    Alright, I see if I can gather a bit of funds, after paying £ 500 to a structural engineer to design a couple of steel beams... :/

    I wasn't joking about the jockey wheels. Shimano's standard ones are 10t I think... might be 9... and you can get an 11 or 12 in there okay. I just put 12t Hope ones on a shimano rd and it is tight for the lower jockey wheel (nothing some pliers won't sort out) but runs fine. The difference in diameter will be greater than between a 23 and a 25.
    Would that be OK on a short cage RD?
  • First.AspectFirst.Aspect Posts: 6,691
    I am pretty sure the upper jockey wheel would be fine. The chain guard on the lower cage is the issue on mine.

    To be honest, I think if you fit a 23t it will work just fine anyway. Shimano err massively on the safe side with this sort of thing. If it doesn't then you can consider other options.
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