Just mindless musings at the moment.

2×11 can be programmed to run from a single lever with sequential shifting. However, does this only work with the xtr 11-40 cassette or could you programme it for a sram 10-42 cassette?

Shouldn’t make a difference as that is just down to the set up of the mech, doesn’t really know what cassette you have.

Not tried it though…

doesn’t really know what cassette you have.

surely it has to know what range the cassette has plus each gear on it to calculate when to do front shifts or just stick with rear ones?

That’s my thinking, it has to know when to shift up/down on the chainset. It can only do this if it knows the ratios. I’m wondering if it’s pre-programmed with the shimano cassette or if you can have a user defined cassette.

It’ll just assume it’s the shimano one – there won’t be masses of difference. As you can tune the sequential shift to your liking, in theory it doesn’t really matter if the shifter thinks it’s on 11t when it’s really on 10t.

But it has to let you select the chain rings. Or do you just tell it where to make the front shift.

you just tell it where to make the front shift… it’ll work out the theoretical ratio for you, based on what it assumes the sprocket/c-ring is, but if that’s not correct then it doesn’t really matter.

the system isn’t really thinking ‘ah i’m in this gear inch’ as such, it’s thinking ‘i’ve just shifted from 6 to 7 therefore next time i need to change the front ring’

I see, so it’s that “front shift between 6-7” that you could move to 5-6 if it was better for you?

yep – you get 2 different syncroshift modes with it too, which you can change on the go, as well as a manual mode, if you’re running 2 shifters.
the e-tube program is ridiculously simply to use too, fortunately!