Will Shimano M6000 Rear Derailleur SG (medium cage) work with cassette other then 42t? I was thinking about buying Shimano Deore groupset to upgrade my ride, checking both older M610s and newer M6000s. The hitch is I want 2x10 set commuter flavor. That means narrow ratio cassette, like 11-25, 12-28 or 11-32. It seemed pretty logical to look for medium cage (GS) rear derailleur version since:


SGS (long cage) was designed with 3x10 in mind (as far as I heard).
I'll be getting transmission capacity like 26, 33 tops which feels too low for SGS with 43 cap.


However, if you look at GS version at Shimano's web site, you'll see:


Low sprocket_Max.    42T
Low sprocket_Min.    42T


As far as I understand it, I should not be using any cassette lesser then 11-42t, which is quite weird to say the least. So, have anyone got experience with using narrow ratio cassettes with RD-M6000-GS, or maybe give some build advice?
The min/max sprocket size spec of 42 does actually make some sense if you think about how the parallelogram of the derailleur works.

On derailleurs designed for large sprocket ranges the cage is moved a long distance vertically as it moves horizontally. At the inner position, the cage is too low and too far away from the axle to work with a small lowest gear sprocket.

That said, you could probably get away with running 2-4 teeth smaller than the specified minimum. If you want to go to a large sprocket of 30 or less teeth, you should be looking at a different derailleur.