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The 11 speed XT rear mech states a capacity of 47T and I am trying to achieve a low gear < 0.55 and wanted to pair the 2 x 11 SLX 34/24 with a 11/46 cassette as that would give me a really nice low gear.
Having bike packed a fair amount I know that steep 10% climbs fully loaded require a fair few watts and I prefer to spin at a high cadence even if I am only travelling at 3 mph. A low gear > 0.55 doesn't do it and I don't want to go 1 x 12
So question is whether the combination will work as I don't get the 47T capacity, but a max 42T rear cassette?
The 47t capacity is used when running a triple chainset - 22/30/40 with 11/40 cassette
That's a shame as I was hoping I'd found a combination that would work. Thanks for explaining.
It might work. I'm running an Ultegra mech WAY past it's specified capacity and it works perfectly.
A Goatlink might help too as it's not a capacity issue, it's a question of the mech handling the larger cassette.
I was wondering as on my gravel bike I am running a rotor 46/30 with a 11-40 cassette and that works fine, so that is a 46T difference. I obviously, never try to go big / big.
A google search on the subject doesn't show up any articles, but I'd rather get a definitive than take a punt and just buy the required parts.
but I’d rather get a definitive than take a punt and just buy the required parts.
You won't get a definitive answer. It'll very much depend on the frame & mech hanger design.
You won’t get a definitive answer. It’ll very much depend on the frame & mech hanger design
I suppose the number of links in the chain has an impact as that dictates the capacity? SO mech hanger and chain stay length both influence that.
I had to a couple of links to run 50/34 and 11-40.
You have two issues I think - no?
The rear mech total capacity (47) and the max sprocket (42).
As you say you’re fine on the former, so put that to one side.
Running a 46 sprocket in a 42 max mech will almost certainly be fine. You might need to play with the B screw a bit and experiment with chain length. Too long a chain is probably not a good idea, as at the right length chain tension will tend to bring the mech away from the sprocket meaning the B screw is less critical, meaning in turn that it will fall back in at the 11 tooth end giving better chain wrap.
I presently have a 36t max M4000 mech running a 42t 9spd cassette on my sons bike absolutely fine. Bit of playing to set up but all tweaking not new parts. Works perfectly.
I'd give it a go. Buy a copy Goat Link from eBay and a SunRace cassette and you'll be ~£55 into the experiment. Unless someone has your exact frame/dérailleur/cassette/chainset combo, you'll not get a definitive answer up front. Fiddle with/reverse/buy a longer B screw off eBay if you need to but you should be able to get it to work with an XT rear dérailleur.
At worst, you might have to give up on a couple of the gear combos as they'll result in a too tight or too loose chain. I'd be surprised if this were the case for you. Above all, report back.
I have a shimano xt m8000 rear mech with a xt 11-46 cassette on the back and running it no problem so cassette size shouldn't be a problem either.
It's only 1x with a 32t front oval ring and a stealth granny ring (no front mech). Not had to use the granny ring and great deal (can count on one hand how many I've times used it over the course of 4 years.)
But shows the long cage mech can handle the cassette no problem.
