Shimano I-Spec A, B and II mounts explained

If you’re a mountain biker and own a recent set of Shimano disc brakes and trigger shifters in Deore or higher, you’ll likely have seen the term ‘I-Spec’. This is Shimano’s wording for integrating the brake lever and shifter into one handlebar clamp. Where it gets confusing is that Shimano is now onto its third generation of I-Spec in just over four years.

I-Spec is an optional choice in Shimano’s line-up, and so you can still purchase standard clamp shifters in all of Shimano’s aftermarket groupsets. If your Shimano gear shifters feature their own bar clamps, then you do not have I-Spec.

I-Spec A

Original I-Spec (now called I-Spec A) was introduced with XTR M985 in 2011. It was designed as an answer to SRAM’s popular MatchMaker, system which provided a cleaner and lighter bar setup by placing the shifter and brake lever into a single clamp.

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An ‘I-Spec A’ shifter can be easily identified by a hook-like nub at the attachment point.

I-Spec A brake levers remain compatible with newer I-Spec B shifters (use silver nut supplied with shifter). If you own I-Spec A shifters, these can unfortunately only be used with I-Spec A brake levers.

I-Spec B

I-Spec II

SRAM and Shimano mix 

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