Short Cage / Cassette / Crank Question

mottone Posts: 7
edited November 2012 in Road general
Hi All,

Quick Techy question. I have a Trek Madone, set up is as follows;

Cassette - Shimano Tiagra 12-30, 10 speed
Crank - SRAM S350, 50/34 (compact)

Im running this with a short cage Shimano 105 rear derailleur, is that correct? This is how it came direct from the dealer. I had to take it to my local bike shop for something else and had a lengthy conversation in which the head mechanic was adament I should have a long cage with the above set-up. I checked with Trek direct and they assured me that the short cage is the right set-up / standard issue. I'm no mechanic myself, but I stuck with the short cage. Am I foolish in doing so?

Just wondered what people in the know thought?

Any help at all is much appreciated.



  • rolf_f
    rolf_f Posts: 16,015
    I think recently Shimano recommended that the maximum size cassette for a short cage on a 50-34 setup was 28 teeth. I think this is now 30 but even the older mechs might be fine for 30 depending on the specifics of the frame design. If you can select big-big without exploding your chainstay, then you should be fine.

    I sometimes run a 29 tooth cassette on my Ribble with Campag 2010 10 speed short cage which isn't supposed to work but is actually fine.
    Faster than a tent.......
  • Cheers Rolf, much appreciated.
    The chap was clearly unimpressed when i stuck with the short cage. More fool me when it all goes wrong!
  • smidsy
    smidsy Posts: 5,273
    You do not say which version of 105 but the 5700a rear mech can certainly go to 30t with a short cage. ... 746860.pdf
    Yellow is the new Black.