Shimano are the trickle down kings (good name for a band, that!). It feels like only yesterday that Shimano unveiled their XTR Trail brakes with an in-line master cylinder design, finned pads and Servo Wave lever. Next minute, these same technologies are present on every brake in the Shimano line up, from the lowly Deore to the earth shattering Saint. Sitting right in the middle, in the wallet-friendly category, are the SLX BR-M666 brakes. [private]
We’ve had plenty of experience with Shimano’s XT, XTR and Saint brakes over the past three years. With SLXs looking virtually identical, save for the battleship grey colour, we had a fair idea of what to expect; reliability, consistency, snappy performance and user-friendly operation. Our brakes were an early release sample (they actually had ‘prototype’ clearly stamped on the bar clamp), but we didn’t think anything of it.
Installation was very simple thanks to Shimano’s Centrelock rotor mount system and hinged clamps on the levers making it easy to install them without removing the grips. We opted to mate our brake lever with our XTR right hand shifter (our test bike was running a 1×10 setup) using the neat I-Spec mounting system. Aligning the brakes was typically easy, as always with Shimano.
The feel of the brakes is snappy and light, with solid engagement and no mushiness at the lever. A prominent (though rather cheap looking) reach adjuster makes it simple to set the lever position, and while there’s no contact point adjustment both brakes pulled evenly and getting the feel between both levers perfectly matched was easy. We’ve come to love the solid, wiggle-free levers of Shimano brakes – the lever pivot assembly is
SLX brakes come stock with resin (organic) pads, rather than sintered metallic pads, and they bed in quickly. Our front brake was at full power in no time, but we had some dramas with the rear – it let off the howl of contamination after just a few minute’s riding. We cleaned the rotor and pads, which improved things, but the bite and power never matched the front. Performance improved when we got loads of heat into the pads with heavy braking, but the power was never up to scratch. Eventually we called Shimano with our frustrations. The problem was with our pre-production prototype samples; some early release brakes were developing oil leaks around the piston seals and between the caliper halves, leaking microscopic amounts of oil into the pads! This problem has been resolved on all production brakes and once we’d replaced the caliper, we enjoyed the performance we expected from Shimano brakes.
The power is excellent with more than enough control from the small 1.5-finger levers, and with the finned pads, heat dissipation issues like brake fade just don’t exist. The organic resin pads aren’t noisy in operation, and pad durability thus far has been great.
While the I Spec shifter/lever conjoined mounting system is very neat, a sizeable crash revealed one downside. Our knee tore off the shifter, which in turn damaged the lever body, ripping out a chunk of aluminium and meaning we had to resort to using a standard band clamp for our shifter instead. Perhaps the interface between shifter and brake lever needs to be more robust.
Despite our drama with the rear brake, we’re still overwhelmingly positive about the SLX system. It’s exceptional value, the weight is reasonable, the feel is unparalleled at this price point and the power is great. Plus you get 90% of the very same technologies as found on XTR at a fraction of the price. These most be close to the perfect working-class brake. [/private]