There are several different brakes (M506, M446, M416, M396, M355) produced for original bike fit and aftermarket sales under the Deore name, but the most expensive Shimano M615 is the affordable Japanese anchor to go for.
The lever uses the blended double barrel, reservoir on top design that’s shared right through Shimano’s brakes. Unsurprisingly, the levels of adjustment and internals are stripped back from the more expensive brakes, but that’s no bad thing. You get embedded Allen key adjustment of the lever reach, rather than an external plastic knob on the knuckle of the blade. That looks neater and it’s very rare that you need to change adjustment so often that a potentially vulnerable knob is worth the trouble.
There’s no Servo Wave cam increasing leverage through the stroke, which means they’ve got 7% less power than Servo Wave-equipped SLX brakes when you stick them on a dyno. That’s enough for perceptive riders to notice on the trail when things get fast and steep, and makes a 180mm or larger front rotor essential for aggressive riding. The disc brakes weigh 492g with a 180mm rotor and adaptor.
There’s no dimpled grip detailing on the broad lever, either. The blade shape is the same, though, and the constant leverage rate up to and including the bite point makes modulation more predictable and easier to judge when traction or balance is really being tested. Feel is considerably better than the over-firm, wooden action of Shimano’s cheaper brakes and well worth spending the few extra notes.
You also get a hinged safety catch-equipped bar clamp with I-Spec shifter integration for a neat cockpit set up. Crucially the simpler lever means we’ve had none of the variable bite point issues that have plagued some more expensive Shimano units over the past couple of years.
At the business end the hose exit angle on the calliper is fixed and can look untidy on some frames – and it’s on the outside edge, where it’s more likely to get damaged in a crash. Pads are secured with split pins not screw-in rods, too, but the original resin sets last surprisingly well even in winter conditions.
The Deore M615s deal with heat well enough to run longer lasting, harder biting sintered pads in the UK or other pad-eating environments. And you can always upgrade to Shimano’s distinctive finned Ice Tech ‘Stegasaurus’ pads for big mountain use. Funnel-based bleeding of the skin, paint and eco-friendly mineral oil internals is also simple if you’re patient. And general reliability of the huge numbers of sets we’ve used on bikes has been excellent.