At first glance, the Tern NBD S5i is reminiscent of a children’s bike with its small tires. 20 inches is tiny compared to the large standard tires of 28 or 29 inches. The wheel has been optimized for two purposes. The manufacturer is particularly emphasizing one: It is an e-bike for non-cyclists, whose comfortable ergonomics should also get inexperienced and untrained bikers on the saddle. The handlebars of the already small bike can be bent so that it can be parked and transported in a small space.
If you stand in front of the Tern as a man about 180 centimeters tall, you only notice the handlebars and saddle, the “body” of the bike is somewhere far below. But this is no longer noticeable as soon as you start. Wide balloon tires were pulled onto the small rims. They dampen bumps and counteract the effects of the small radius. Their width leads to a secure grip on the road and the tires create a full feeling when rolling.
The bike builds up steeply over the tires. And that in the literal sense. On the Tern NBD you sit completely upright without any forward leaning. The hub of the front wheel is almost directly under the handlebars, the bottom is just in front of the rear wheel hub. The seating position is like sitting on a chair. The advantage: an upright posture leads to a clear view of the traffic situation and does not put any pressure on the wrists and neck – otherwise typical discomfort or even pain zones for older cyclists.
The flat wheel center leads to a low center of gravity, which makes the bike more stable in every position. The NBD has a flat and long step-through. You can therefore climb up and down very safely. The foot can be guided over the frame without twisting. An important point for people with joint problems. You can easily get both feet on the ground at any time.
The upright posture means that the weight rests on the buttocks and the shoulders are not burdened either. The typical tension in the wrists, neck area and neck muscles are avoided in this way. The NBD has fat balloon tires but no front fork and rear swingarm suspension. A seat post was installed for this. In the field of sporty driving, such a solution is not the first choice, here it fits very well. The suspension is necessary to cushion bumps like hitting a pothole. Because the seated position and the engine doing the work mean that you can sit very loosely on the NBD. In other words: You ride without tensing your own muscles, a hit from below goes directly to the intervertebral discs. Thanks to the support, that can’t happen.
The bike is powered by this combination: a Bosch Performance Line drive with 65 Nm of torque and up to 300 percent pedal force support, a maintenance-free belt, 500 watt-hour battery and a five-speed hub gear. One might ask why only five gears, isn’t one with eight or even eleven gears better? Not here, the five-speed gearbox withstands the 65 Newton meters of the engine. The circuits with finer gradations do not. As an aside, the more solid circuitry is also noticeably more expensive.
With the motor, the bike is powerful, even if a lot of weight is moved by a child seat, for example. Gradients of more than ten percent are no problem – the bike with its relaxed seating position is of course not intended for extreme climbs on the mountain. Even with the small tires, the Tern runs safely and quietly. The almost straight handlebars give you good control and the front wheel has enough traction, even if most of the weight is on the rear tire. Even at 25 km/h the bike runs safely and quietly. If it goes downhill, we slowed it down at just over 30 km/h.
Due to its short length, the Tern is very handy. It only requires a small turning circle and can be easily moved by pushing. You just don’t bump into everyone like you would with a big wheel. It’s not a toy, though. The fixed rear rack carries 27 kilograms. The bike is approved for a weight of 140 kilograms. For the small bike there are bags and baskets for the back and you can also hang bags or baskets in front of the handlebars. All this was included with the test bike, but the accessories would have to be ordered separately. If you like, you can convert the bike into a pack donkey. We particularly liked the baskets that snap onto the rear rack. A child seat has not been tried, but here you will benefit from the low height of the carrier.
The Tern NBD is a bike for different body types. Tern states that it can be used from 147 to 190 centimeters tall. We even think that’s realistic. The seat post has a very wide adjustment range. In addition, the position of the handlebars can be easily adjusted with a lever system. The bike can therefore be used by people of very different builds and can be adjusted to their body size in two simple steps.
On the road, when pushing and parking, the Tern NBD takes up little space. This also applies if it is to be stored in a holiday apartment. If you like, you can even set the bike up vertically. Then it rests on the rear wheel and the specially shaped carrier. So it requires little floor space. Also useful when transported in an elevator. Big 28s don’t fit in many elevators.
In addition, the seat post can be removed and the handlebars folded down, so you get a compact pack size. In addition, you could mount folding pedals, which further reduces the width of the bike. To avoid misunderstandings: The Tern is not a folding bike – the frame does not fold. At 23.4 kilograms, the NBD is not a lightweight either, besides that you can carry one or even two wheels in the back of any station wagon, SUV or minivan without having to remove the front wheels and without a carrier behind the car.
What is not working? The Tern is not a mountain bike. Because of the upright posture, jumps should be avoided and higher curbs avoided. When going downhill, you have to estimate how far you want to go. We would set the tolerance limit at just over 30 km/h. In the test, the Tern was moved several times over a commuter route of two times 15 kilometers. This is also easily possible, even if the bike is intended for shorter distances and not for long tours.
Anyone who essentially wants to cover shorter distances in comfort benefits from the advantages of the concept and does not have to put up with any disadvantages. The tires move the bike forward on any road surface – cobblestones included. If the pavement gets very rough, you have to ride more carefully – as with almost any bike. Contrary to what you might think, the Tern NBD copes well with field and forest paths and grass surfaces. However, practice in cycling is helpful on difficult surfaces. If you often leave a covered road, you should replace the pure road tires with rubber with a more profile.
We were convinced of the driving qualities. The NBD S5i is the right choice if you appreciate the compact dimensions, the easy on and off and the comfortable, secure seating position. Even a good rider without restricted mobility can enjoy this bike. Aside from long tours, the bike is also good for longer distances. The driving experience is direct and safe – you should only avoid acrobatic jumps. Even with the small tires, it copes well with dirt roads and easy terrain, it is not suitable for real off-road. In short, the bike is pretty much perfect for the intended target group. You only notice how much easier such a mini bike is to move in traffic when you try it out in comparison. For someone who has not ridden a bike for a long time or suffers from limited mobility, the NBD concept should be a very good choice anyway.
With so much sunshine, there is also a dark spot. The Tern NBD S5i is quite expensive at 5399 euros. That’s not surprising. Other premium brands such as Riese and Müller or Brompton price the same. The bike is worth the money, but you also have to have the finances. The NBD P8i variant has somewhat slimmed down equipment – weaker motor and battery – and is therefore significantly cheaper, but the NBD P8i is also a price grab at 4499 euros.
