It looks like 2016 is the year the battle for the potentially huge e-MTB market heats up, with Shimano releasing an off-road specific version of its STEPS pedal-assist system.
Called, somewhat unimaginatively, STEPS MTB, the setup consists of a more powerful pedal-assist motor capable of putting out 70Nm of torque paired with a higher-capacity 500Wh Lithium Ion battery. Shimano’s model designation for the setup is E8000, which puts it on a par with its human-powered Deore XT-level drivetrain.
Shimano's STEPS MTB system looks set to take on the might of Bosch
The group consists of the motor unit, a choice of hollow or solid arm cranks and a dedicated chainring in either 34t or 36t sizes. The control and display units will familiar to anyone that has spent any time on Shimano’s electronically shifted Di2 mountain bike drivetrains. You use a Firebolt-style shift lever to control the three levels of assistance on offer, while the colour LCD display shows the mode you’re in along with range remaining and also your gear, if you’re using a Di2 groupset. You can get into the settings of the bike via a Bluetooth connection and Shimano's E-Tube software. ]
As you'd expect, the system integrates with Di2 mountain bike drivetrains
Bosch’s burgeoning dominance of the e-MTB motor market is obviously a cause for concern at the Japanese drivetrain company, with the somewhat sluggish release of an off-road ready system having given the German giant plenty of time to establish itself in what was originally an unfamiliar market. It's almost certain that given Shimano's longstanding relationship with bike manufacturers that it'll be able to claw back a decent share of the market regardless.
Is this the shape of things to come?
In spec terms, the two systems seem relatively evenly matched. In Performance CX specification, the Bosch motor puts out slightly more torque at 75Nm, while battery capacity is on an even pegging at 500Wh. You do get a marginally broader choice of assistance settings with Bosch, with four rather than three settings. Both feature a walk-assist mode, a welcome relief to anyone who’s had to push the heft of an assisted bike up a hill.
The display unit is visually similar to the Di2 unit
One area where Shimano seems certain that it system has an advantage is that it shares its Q-factor (the distance between the outside edges of the crankarms) with its conventional chainsets, which helps make for a more comfortable and efficient pedalling style. Shimano also claims its motor allows for shorter chainstays on the bikes it’s designed around, though we don’t have confirmed dimensions versus the Bosch system. If true, it’d help make e-MTBs handle much more like their flesh-powered brethren, a boon on a bike that’s always going to be more cumbersome than most.
The Bosch unit also uses a small 14t driver cog and a crank that's geared down, while Shimano system has the cranks and rings connected directly. Depending on the internals of the units it's possible that this will give them an efficiency advantage, leading to better range for a given battery capacity, though this is pure speculation.
Shimano says the new system will be available in October 2016, just in time for the release of many manufacturers' 2017 bikes. Regardless of how you feel about e-bikes, they definitely aren’t going away any time soon.