Review: Tern NBD S5i

There’s one big problem with electric bikes as an alternative eco-friendly mode of transportation: Most people who own one already have several bikes (guilty!). It isn’t really reducing carbon emissions if the person who buys an ebike was already riding a bike, skateboard, or scooter.

Some companies have opted to appeal to non-bike-riders by making bikes bigger or more carlike. But I think this approach is misguided. I ride a bike; I don’t ride motorcycles. Big bikes are heavy and scary, especially if you’re smaller or mobility-challenged. I’m not chasing thrills on the highway; I just want to go to the grocery store without worrying about parking.

The Tern NBD accomplishes this task with one specific design feature—a step-through so low that the whole time I was riding it, all I could think about was comedian Frankie Quinones’ CholoSpin. Just cruise it out, homey. It’s way too expensive if you yourself are not mobility-challenged, but I have to admit that for weeks, it was the easiest bike to grab on my way out the door.

Let’s talk about this frame. Many cruiser electric bikes advertise themselves as step-throughs. The top tube is lower than a normal bike, so it's easier to step through, instead of over, to mount it. (I like a horizontal top tube because it's easier to carry, but that's another thing entirely.) In practice, the top tube is usually still straight. There's more space, but not always as much as you'd expect.

The NBD's top tube is so low that it sits directly on top of the Bosch Performance motor. You only have to lift your leg about 15 inches off the ground, or about 4 inches lower than the already-low step-through on my Tern GSD. It’s so low that my muscle memory couldn’t handle it—I kept automatically flinging my leg over with many extra inches of clearance.

I’m not mobility-challenged. Still, I can imagine having hip or knee problems and finding this bike very easy to bestride. The problem that it solved for me was much more shallow—I like wearing long, floofy dresses around the house, but I usually have to change out of them to skateboard or bike around. With the NBD, I didn’t have to worry about flashing my neighbors when I biked to get burgers with my kids.

Pretty much everything about the NBD is designed for extreme comfort and ease of use—more or less, just like a CholoSpin. The handlebars are curved around so you can sit up easily, and the grips themselves are big and ergonomically designed for resting your wrists. The Bosch display is huge and bright, and the buttons are also big and clearly labeled, with touch bumps so you can identify the button easily.

There’s a suspension seat post, which, to be honest, I was surprised to not like; I’m just used to riding with suspension on the front fork instead. It also has sturdy, comfortable, Schwalbe balloon tires, extra-big foot pedals, and a low-maintenance Gates belt drive. Like the rest of Tern's bikes, it’s compact, with its trademark fold-down handlebars for easy transport. It can also be stored upright, sitting on the rear rack. The handlebars and seat are easily adjustable. It can fit riders as short as 4'10"—both my 5'11" spouse and my 5'2" self were able to switch bikes mid-ride when my 7-year-old decided she wanted to bike with my husband instead of me.

Finally, there’s an Abus lock built into the rear wheel. I wouldn’t use it as your primary security measure, but it’s pretty convenient when you discover that your daughter has taken your only bike lock, about 10 minutes before you’re supposed to meet someone for lunch.

Overall, the NBD is surprisingly powerful for such a little bike. Its Bosch motor has a torque of 65 newton-meters and a Bosch PowerPack 500 battery. It easily got up to 20 mph (it's speed-limited in the US). The motor got me up the steep, 15 percent Battery Killer hill near my house. The battery is shockingly long-lived. When it had halved, I took an impromptu trip to the beach and rode for about 18 miles. When I got back, the battery had only dropped by one bar. 

It comes with a rear rack that can accommodate a child seat, and it can accommodate Tern's front rack. The frame has been tested according to stringent EFBE standards, and the Bosch motor has also been safety-tested according to UL safety standards.

I found the NBD easier to ride and use than even popular cruisers like the Electra Townie Path Go. The step-through is extremely low, and the bike itself is so small that it's easy to maneuver, even when I'm not riding it. When I was recovering from Covid, I didn't have to worry about getting thrown off balance while riding it. It's small enough that I have no problems getting off and pushing it when my 5-year-old decides he wants to stop biking and pick apples off a tree on the way home. 

However, the value proposition is just completely different if you don't have mobility problems. The model I tested is the NBD S5i, which costs $4,699. The cheaper NBD P8i has a Bosch Active Line motor instead of the Bosch Performance motor and costs $3,899. As a mobile person, I wouldn't spend that much on a bike that isn't as fun for me to ride.

Then again, if the NBD’s step-through makes it possible for you to ride when you thought you never would again … well, it’s hard to put a price on that.

Update, October 19 at 6 pm EDT: The story has been updated. A previous version of this story stated that the Tern NBD does not have an internal gear hub; it does.