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How do I choose between, short, medium, and long cage length for rear derailleur

vickaiservickaiser
in General Training Discussions

Changing to compact crank as well as upgrading to 11 spd.  Will be running 50/34 front and 28/11 rear.  Ordering my rear derailleur, do I want a short, medium, or long cage length?

Comments

  • Paul HoughPaul Hough
    Victor - I'm not the expert but I don't think you need a long cage derailleur unless you are going to put a 32 on the rear. Most likely a medium cage is what you want for a compact with an 11-28 to cover hilly courses. Hopefully a gearhead will come on here and set me straight if I'm wrong.
  • morpheusmorpheus
    Paul's right.

    It's my understanding, also, that you need a long cage only if you plan on using some kind of mountain bike cassette setup (think 30 or 32 tooth cog). This kind of setup is popping up more frequently on the road bike scene for big climbs.

    So, if you're sticking with a 28, medium is just fine. Gonna put a 30 on the back? A long cage is best. It can be done with a medium but the guy in the shop better be good at what he does.
  • vickaiservickaiser
    Just talked to my bike mech and he insists a short is good to go. Now sure what his aversion is to the medium. What say the geeks here re the short?
  • morpheusmorpheus
    I have no prob with that. Can't say anything pro or con about it.
  • Al TruscottAl Truscott
    I have 11-32 rear on both TT 53/39 650c) and road (50/34 700c) bike, with medium RD (Wi-Fli, or Ultegra). TT is Di2, road is SRAM Force. I've had no issues in finicky shifting with either in multiple years of use. Bike tech just keeps improving every year; what may have been true in 2010 no longer applies IMO.
  • jalesliejaleslie

    On a similar note, I have a Durace RD on my TT bike, 10 speed.  I have a 12-28 now, but for Canada I'm thinking I need a 32 (or 30 if available?) as I'm gonna be at about 3.1-3.2w/kg @ FTP.  Does anyone know if I'd have to switch the RD?  I have no idea what is on there now, other than it's a Durace!  

    Thanks in advance. 

     

  • Rich StanbaughRich Stanbaugh
    Hi Victor - I can't add much to the discussion about cage length. I've only had two considerations in the past. The first is "drop" and the second is max gear size. Drop is a specification of the derailleur and represents the difference between the teeth on biggest gear and smallest gear on the cassette. So a 11-28t cassette has a drop of 17. Depending on what kind of cassette you want to ride, the derailleur can limit you with this spec. Max gear size is also a spec. My Dura Ace DI2 has a drop of 18 and max gear size of 30t.

    With respect to which cassette you are choosing, check out my post on how I think of gearing. It may/may not help, but I would be interested in your thoughts.
    http://members.endurancenation.us/Forums/tabid/57/aft/18742/Default.aspx

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