Tern's folding e-bikes have always been ruthlessly practical, but the HSD takes things up a notch. With fully adjustable ergonomics, it's also kitted out with super-solid racks front and rear that are ready to take over the job of carrying your shopping, your deliveries or even your kids.

The HSD slides into the middle of Tern's e-bike range, between the ultra-compact Vektron and the extra-long GSD, which is basically designed to bring cargo-bike carrying capacities into a form that's easier to ride. Thus, Tern has kept the HSD small enough to be portable, and also given it quite a hauling capacity – up to a maximum gross vehicle weight of 170 kg (374 lb).

As far as storage, the seat drops in and the handlebars fold down to get you a bike that's easy to fit in the back of a car. It can also stand up on its chunky Atlas rack if you're really short of floor space.

That rack can hold up to 60 kg (132 lb) of whatever you want to stick on it, and Tern will happily supply you with all manner of attachments back there, including panniers, trays, baskets and bags. It'll also take a detachable kiddie seat, and if you've got a munchkin on the back, you'll appreciate the step-thru frame design – swinging a leg over a bike with a top bar can be pretty treacherous when you're balancing an awkward, wriggling weight on the back. Rounding out the carrying capacity, a sturdy combo mount on the front lets you stick a rack, basket, bag or whatever you need on there.

In terms of comfort and practicalities, it looks terrific. There's a Suntour suspension fork up front, and big, fat, bouncy-looking Schwalbe tires with RaceGuard puncture protection on board. Some models have Thudbuster suspension saddles to coddle the buttocks as well, and there's hydraulic disc braking and a built-in Abus frame lock for quick stops. The handlebars and seat are adjustable to suit riders from 150 to 195 cm (4.9 to 6.4 ft), and front and rear lighting is built in.

As for the drivetrain, there are different models, but all use Euro-legal Bosch motors. Specifically, gentle Active Line Plus ones with 400-Wh batteries for the lower priced models, with the €3,099 (US$3,099) HSD P9 running through a Shimano Alivio Shadow RD groupset, and the €3,699 (US$3,699) HSD S8i using a lovely Gates belt drive back to a Shimano Nexus 8-speed in-hub gearing system that's beautifully protected from the weather and makes chain grease an issue of the past.

The top-of-the-line €4,999 (US$4,999) HSD S+, however, looks much more interesting. It uses Bosch's Performance Line motor, which is significantly torquier, and offers a slightly larger 500-Wh battery. Like the S8i, it also uses a clean, quiet belt drive, but in this case it goes back to an Enviolo Sport 380 hub.

Enviolo deals exclusively in NuVinci continuously variable transmissions, and the 380-series NuVinci gear has the capability to change the gearing smoothly and automatically as you ride. Effectively, you just set how fast you want to pedal, and the transmission will adjust itself instantly, with no clicking or torque loss between shifts, to keep you working exactly as hard as you want to. It's like the problem of choosing the right gear simply disappears, whisking a range of annoying gear selection scenarios straight off the table.

It's rated for significantly more torque than the Bosch motors put out, and up to 500 watts of continuous power, so it should be reliable under the demands these little 250-watters place on it. An e-bike with an automatic CVT sounds to us like an absolute dream, about the friendliest and most fuss-free set of wheels we can imagine.

The HSD in all its variants will launch at tomorrow's Eurobike Urban Mobility Days in Frankfurt, Germany. Check out an overly long and indulgent video below.

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