Am currently speccing up a build for a newly ordered 29er frame which will be run 1×10 (no front mech option).

I’ll be using a 11-36t cassette and would like to use a short (or medium or whatever the XT GS version is?) cage rear mech if possible but the description says 35t maximum. Now does this refer to the size of the front ring being used (it’ll be 32t) or the biggest cassette sprocket?

My head says it should be fine if i’m not using a front 42/44 ring but thought i’d check with the collective brain of STW first before i order anything, cheers.

it’s the difference in size between biggest front and smallest back (or smallest front/biggest back) – basically the amount of slack the mech can take up.

Yes you can run a short cage mech. Doing the same myself with a 32 Chainring and a 12-36 cassette.

The problem you may have is that Shimano dont make a short cage 10 speed mech you would have to use SRAM. The only short cage MTB mech Shimano do is the sain which is still 9 speed only as far as I know.

I went X9 shifter & mech and it is fine.

Thanks guys.

Is this not a 10sp short/medium mech then?

http://www.chainreactioncycles.com/Models.aspx?ModelID=67201

I thought the GS is the shorter version to the SGS?

Shimano do Long and Medium cages in XT etc

SGS = Long
GS = Medium
SS = Short

Here is the 9 speed Saint Short cage and you can see the difference

http://www.chainreactioncycles.com/Models.aspx?ModelID=27695

The GS Medium is fine for me, i assume it’ll just give a bit more clearance than the long cage one?

Hopefully going to buy today so confirmation would be great.

My assumption is that shorter cages (than the sgs) should give slightly ‘snappier’ shifting and move the mech a bit more out of harms way? How much shorter is a gs compared to sgs?

My confusion though is that if it’s the difference between big front and small rear (44-11=33 on most triple bikes) why are sgs mechs always the standard when medium cage mechs (35t allowance) would surely work fine and better? I’d also assume they’d be slightly cheaper to manufacture as it’s less metal?

Cheers

MrTall from the CTC website, to avoid any confusion;

Rear mechs have two kinds of capacity and the numbers of teeth can be a bit similar. So check which of these is being talked about:
1) Sprocket capacity – is the biggest big rear sprocket they can handle. It depends upon the geometry of the mechanism. Mechs with bigger sprocket capacity swing further down as they swing inward. It’s also influenced by the dimensions of the gear hanger on the frame; these varied a lot in the past and road bikes still tend to have shorter ones than mountain-bikes.

Manufacturers have to be a bit cautious in their claims, so you can often use a couple more teeth than they say – sometimes a lot more. (I’ve used a 32T capacity mech on a block with a 36T chainring bolted on the back, and that on a bike with road dropouts!) Sometimes the smallest rear sprocket is also stated, but this hardly matters at all. Some mechs, however, will foul unusually big sizes of top sprocket and bear in mind that anything bigger than 14T is nowadays unusual.

2) Total capacity – is the biggest difference in total numbers of teeth, front plus rear, that the mech can handle without letting the chain hang loose. Say you’ve got a 11,13,15,17,20,23,26,32 cassette and 24,36,46 chainset. The biggest combination is 46+32 = 76T, smallest 24+11 = 35T. So you’ll be wanting a mech with 76–35 = 41Tcapacity. But again, you can generally push it a bit.

Provided the chain is made just long enough to engage big and big (if it’s too short for that you might demolish the mech by mistakenly doing that!), the worst that can happen is it hangs loose and maybe rattles a bit in small and small. But modern gearing provides so much overlap you’ll never need this combination. Your mech needs only to cater for small plus “smallest-used”. Maybe you want to shift the aforementioned gears with an old Deore mech having 38T total capacity and are wondering what is the smallest sprocket you can use with that. Your starting point is still the big+big 76T: subtract 38T capacity, also subtract the inner chainring’s 24T = 14T. Voila: all except the top two sprockets will work fine on the inner ring – and as for them: vive la catène flottant! CJ

Might not be helpful Steve but my 5 came 3×9 11-32 cassette and 22, 32, 44 at front and worked fine with a medium cage XT mech

Cheers guys, i’ll order the medium cage one later today.

Hi Mark *waves* 🙂