The evolution of e-bikes continues apace, with Trek revealing a radical new 29er pedal-assisted version of its Supercaliber.

With most e-bikes configured in trail or enduro trim, the idea of an XC frame with a mid-drive motor is unusual. Conventional logic dictates that XC rides love to suffer and obsesses about grams, right?

Trek’s product planners feel a touch differently and their latest product initiative is the E-Caliber. The Wisconsin company has taken its ultra short-travel Supercaliber XC frame and added a Fazua mid-drive motor and battery pack.

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You can ride it as a normal mountain bike too

Powering the E-Caliber’s 55Nm mid-drive motor is a 250Wh battery pack, which can even be removed for riders who wish to ride their E-Caliber as an unassisted bike. That drops the weight by 2.7kg, but would be defeating the entire concept, although the battery cavity can make for an enormous snack and spares stowage compartment.

Trek claims that its E-Caliber should have adequate battery endurance for 30km in extremely steep terrain, with long climbs, or up to 80km, if you are rolling along on flatter gravel roads or flowing singletrack.

The Supercaliber and E-Caliber share a similar Isostrut rear suspension configuration, which offers only 60mm of travel. Trek’s new e-bike rolls much larger tyres than its non-assisted XC racing sibling, with Bontrager XR3 Team Issue 29×2.4” replacing the Supercaliber’s 2.2” rubber.

Trek has equipped the E-Caliber range with stouter forks, a blend of Rockshox 35mm stanchion products and Fox 34s, depending on spec, all offering 120mm of travel. That also tips the E-Caliber’s head angle to 67.5°, making it 1.5° slacker than a Supercaliber, with reach growing by 15mm, on a size large, to 470mm.

You can go sub-16kg with an E-Caliber

The available Trek E-Caliber builds vary from 18.49kg down to 15.77kg. Ensuring they all stop decently, the entire range features 4-piston brakes.

A peculiar specification detail is that both the premium Trek E-Caliber 9.9s, with either XTR or XX1 AXS, have fixed carbon-fibre seatposts, instead of droppers.

Trek’s E-Caliber range is priced from £6300 for the entry-level 9.6 (RockShox 35 Gold RL and Shimano Deore 1×12)) to £11750 for an XX1 AXS equipped 9.9.