I have XT brakes (785 or something) they are clamped to the bar as usual
the box states the are I spec B.

I’m looking to goto 1×11 so looking at an slx shifter.
noticed theres an option of Bar clamp or I spec B or I spec 2.

If I got the I spec B one how does it attached and do I need any extra gubbings?
or should I just get a bar mount.

Bar clamp every time. You’ll thank me when your brakes fail and you need to change them for the opposite type of ispec you have.

Had a similar (ish) issue recently and went for bar mount, just to future-proof things. Not as neat and tidy, but it worked. Very frustrating though…

If i remember correctly, they come with a bag of gubbins that clamp through the brake lever band

I have an iSpec-B XT 11 speed shifter that I’d be happy to sell. Unused, brand new…

Yes, iirc the shifter comes with the wee bolt that you need to attach it to the brake.

I-Spec is awesome.

Recently went 10 speed (my current Zee brakes were ispec B). The saint 10 speed ispec B shifter came with the 3 bits to allow attachment to the Zee. I’d previously made the mistake of buying a Saint shifter off ebay but it was just ispec, not ispec B, and thus not compatible with ispec b brakes.

Also attached this shifter to the latest Deore brakes with no issues.

If you do find you need the bolt, like what I did – CRC sell them
http://www.chainreactioncycles.com/s?q=shimano+i-spec+b+bolt+%26+nut+unit&cat=product
I had to buy 2.
The black ones bolt through the clamp of (I think) newer shifters, so you’ll either need those or just the silver bolt.

i-Spec 2 is new 1000 series only (eg, M8000) and is a different style clamp without the bolt. They aren’t compatible.

And it’s for the above faffage that I am going for a BAR MOUNT shifter now….
(Switching form m785 to m8000 brakes!)

DrP

Plus no matter how much loctite I used, one of my ispec shifters had the habit of loosening, the bolt falling out, then the whole thing dropping off during the next descent when all chance of finding the bolt was gone.

Disc rotor bolts are a good substitute though.

Bar mount for my next set.