Short Cage / Cassette / Crank Question

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mottone
Posts: 5
Joined: Tue Dec 06, 2011 16:23 pm

Short Cage / Cassette / Crank Question

Postby mottone » Wed Nov 14, 2012 12:24 pm

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.

Cheers.

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Rolf F
Posts: 13574
Joined: Sun Oct 26, 2008 09:29 am

Re: Short Cage / Cassette / Crank Question

Postby Rolf F » Wed Nov 14, 2012 12:33 pm

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.......

mottone
Posts: 5
Joined: Tue Dec 06, 2011 16:23 pm

Re: Short Cage / Cassette / Crank Question

Postby mottone » Wed Nov 14, 2012 20:35 pm

Cheers Rolf, much appreciated.
The chap was clearly unimpressed when i stuck with the short cage. More fool me when it all goes wrong!

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smidsy
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Joined: Tue Jan 17, 2012 20:52 pm

Re: Short Cage / Cassette / Crank Question

Postby smidsy » Thu Nov 15, 2012 05:53 am

You do not say which version of 105 but the 5700a rear mech can certainly go to 30t with a short cage.

http://techdocs.shimano.com/media/techd ... 746860.pdf
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