Shimano has officially unveiled its new EP810 eMTB motor, with 100Nm of torque, 750W of peak power, and a system that can change gears and adjust assistance without you touching the controls.At 2.3kg, it weighs 300g less than the Avinox M2S and 400g less than Bosch's Performance Line CX-R. Shimano has managed to drop 400g compared to the EP801, while increasing torque from 85Nm and peak power from 600W.The interesting bit, however, is how Shimano has brought its automatic shifting and adaptive motor assistance together. It calls this True Auto, and the idea is you can spend less time processing modes and gears, and concentrate more on your riding.The new EP810 features on the new Honda RN0 eMTB, which Nick Clark tested for BikeRadar and described as "one of the noisiest bikes I've ridden". Has Shimano already fallen behind in the eMTB motor race? Its latest motor has me worried Choosing the right gear Shimano's third-generation Auto Shift works with compatible Di2 drivetrains, automatically selecting gears based on cadence, rider input and terrain. Shimano Auto Shift has been around for a while, but the EP810 gets the third-generation version, with updated software and motion sensing to help it decide when to change gear.With a compatible Di2 drivetrain, the system uses cadence, pedal torque, speed and gradient information to make those decisions. You can adjust its preferred shifting cadence using the bike's controls, so you're not tied to whatever setting Shimano has chosen.Auto Assist works alongside it in the new Trail+ mode. It adds support on climbs, with Shimano saying it also manages the power to help maintain traction and keep the front wheel down. On flatter ground, it reduces assistance to save battery, while support is backed off on descents.Other motor systems, from the likes of Avinox and Bosch, already offer automatic assistance.We'll be keen to find out how well Shimano's motor and gearing work together when a trail gets complicated. Will it drop into the right gear as you approach a steep section, or leave it until you're already struggling?Auto Shift is available with Di2 versions of XTR, Deore XT, Deore, GRX and CUES, so you'll need a compatible electronic drivetrain to use it.Getting going again Despite weighing only 2.3kg, the EP810 delivers 100Nm of torque and 750W of peak power, making it one of the lightest full-power eMTB motors around. Shimano There are a few more features intended to help on technical climbs, especially when you run out of momentum.Hill Hold helps prevent the bike from rolling backwards when Walk Assist is engaged on a slope. Lift & Shift is particularly useful in theory. If you stall in a hard gear, you can lift the rear wheel and double-press the assist-down button in Walk mode to shift into an easier one before setting off.Shimano has also included two features for when pedalling gets awkward. Assist Remain smooths support if your pedal strokes become uneven. Assist Carry Over, effectively motor overrun, continues to give you a little assistance after you stop pedalling. You can adjust how long that lasts.What's changed on the motor? Shimano's new 720Wh battery weighs approximately 4.1kg, giving it an energy density of 176Wh/kg, some way behind the latest batteries from Bosch and Avinox. Shimano The EP810 uses a magnesium housing with cooling fins and Shimano says changes to its internals have helped reduce noise. It provides assistance at cadences of up to 160rpm.While Shimano's 2.3kg motor is impressively light, its new 720Wh battery weighs 4.1kg, giving it an energy density of approximately 176Wh/kg. That's some way short of the latest batteries from Avinox and Bosch. Maybe Shimano has prioritised durability, or price.There are new top-tube and handlebar displays, a wireless controller and a USB-C charging module. The Shimano Connect app handles settings, ride tracking and firmware updates. Shimano's new D-FLY+ wireless protocol isn't compatible with earlier D-FLY equipment. The new SC-EN700 top-tube display shows key ride information, including speed, battery level and assistance mode, while keeping the handlebar free of clutter. Shimano If you're wondering whether you can fit the motor to an older EP8 bike, the answer isn't straightforward. A Shimano spokesperson told us: While the EP810 retains the same mounting bolt locations as the EP801, the overall shape and dimensions of the drive unit have changed. As a result, most manufacturers will need to update designs to accommodate the new system.So the bolt pattern matches, but a straightforward retrofit can't be assumed. UK pricing and availability are still to be confirmed.We'll be interested to see whether True Auto makes tricky trails easier to ride, or whether it's something we'd rather switch off.