Trying to save myself a few pennies here, but only if its worth it.
I have a M786 XT rear mech with a 42T chainring,, looking at the compatibility for the long cage version it only goes up to 41T.
Will I get away with the extra 1T or do I need to change?
The size of the ring is irrelevant to capacity. Capacity is the difference between the max/min sizes on the cassette and the max/min sizes on the rings.
So if you've got 11-36 cassette (25) with a 28/42 ring (14) it would still total (39) less than the capacity (41)
I'm assuming you mean 42T on the rear on a widerange cassette?
I used that combo but I think with a medium cage not long. There's basically 2 things here, outright mech compatibility- which is fine- but also chain slack management, which depends also on chaingrowth in a full suss and may or may not be fine.
But, while it all fitted and worked, it was highly strung and sensitive to setup. I could get it working perfectly but it didn't tend to stay that way for long. So I fitted a OneUp radcage, which fixed all of that and basically made it work like factory. It's an extra expense but if you want to do wide range and 10 speed I can't recommend it enough...
(we're getting to the point where just changing to 11 speed could make a lot of sense tbh)
That's for the advice, I think mine is a long (not sure how id tell but it seems pretty long). Is this an advantage to try this setup?
The advantage is cost. The payback is your time spent getting it working, and possibly spending 50-100 quid on extras to make it work better.
As Northwind says, unless you have the whole drivetrain already and don't mind putting time into getting it running or aren't fussed about perfect shifting, you might do better to get M7000 and have done with it...
ok good call
il sell what iv got and get m7000
I'm using that mech fine with a 42T (sunrace cassette) without all the sensitive faff by fitting a £15 Pilo mech hanger mod thingy (same idea as the Wolftooth goatlink).
Not sure if I've been lucky but been running reliably for a little while now.
Iv ordered a zee shifter, maybe il see how it runs when it turns up. What difference would the mech hanger make?
Good hangers make a huge difference to shifting accuracy.
The thing mentioned is more than just a hanger, it relocates the mount point so moving the pivot point. This is more or less what you're doing with the Radr cage, too. TBH, I didn't know Pilo did that. There is an element of suck it and see for any expansion mod though. People running SRAM have an easier time as the geometry of their derailleur suited the oversize cassette better.
We my skills I think its going to be best to just get the SLX M7000, anybody know of a decent and well priced 10spd Chain?