Difference between Shimano I-Spec types A and B?

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  • Difference between Shimano I-Spec types A and B?
  • Premier Icon mactheknife

    The only info i could find was on MTBR and i cant find it again, basically the B type are for 2014 onwards but they are back compatible with older shifters and brakes. A type are for everything pre 2014 but are not forward compatible. i.e. you cant use with the new B type.

    Thats the gist i got but i may be completely wrong. 😯

    Premier Icon mactheknife

    From MTBR

    Originally Posted by Live2rideUtah
    Now I am wondering what I spec I need to get for the xt’s on my 2012 superfly. Can someone take a pic of the hole that I need to have in order for the above linked covers to work with my set or direct me in the right direction to what the hell I’m looking for. Thanks
    As yours is a 2012 model bike it’ll be fitted with the ‘original’ I-spec levers. The new I-spec standard has only just been introduced and only a few shops have received new stock, and 2014 bikes will come fitted with it.

    After looking at a couple of online retailers that have the new models, it seems the new I-Spec levers, shifters, and adapters are designated with a “B” after the model number. So, for example the original levers were BL-M785, but the ones with the new I-spec standard are BL-M785-B. Similarly, the original I-spec shifters were SL-M780-I whereas the new ones are SL-M780-B-I, and the new covers/adapters are SM-SL78-B.

    So, as long as you avoid anything with a “B” added to the model number you should be alright. However, this may be easier said than done, as bike shops/online retailers are already confused by the sheer number of parts they have to stock with tiny differences, so what are the chances they’ll know if what they’re offering you is original or ‘B’ ?!?


    I think there is a diagram on the Shimano website that explains this, but from memory the only combination that won’t work is the A-spec shifters with B-spec brake levers. Everything else fits together, and the b-spec shifters come with bolts to fit a or b spec levers – Shimano seem to have made something simple very confusing!


    Basically you can use new shifters with old brakes (this is what I am doing) but you cant use old shifters with new brakes.

    You need A brakes to work with A shifters, no other combo will work with A shifters.


    Hi all, I got some SLX i-spec type A shifters off the ‘bay recently and looking to pair them up with some SLX i-spec type B brakes, but I can’t for the life of me find any info on the difference(s) between I-Spec types A and B.

    Is there any? Will they work together?

    Can anyone shed some light on this?

    Cheers T


    Ok thats great, thanks everyone (not you shimano). Looks like im going to have B spec brakes with A spec shifters…

    Time to fire up the milling machine.



    Funny, that quote from MTBR was from me!

    Others above have done a pretty good job of explaining what will and wont work, but for completeness here’s the official Shimano diagram…

    Premier Icon hutchweb

    I wonder how many people, like me, have read this then gone out to the shed / garage with their new / sh purchase, offered things up then gone “oh crap!”
    Incompatible compatibility.

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