Test / E-Bike: The Tern HSD enters its third generation. Originally introduced in 2019 as the little brother of the extremely successful GSD, the HSD has continuously evolved over the years. With the latest iteration, the HSD Gen 3, the manufacturer promises even greater payload capacity, the latest Bosch drive technology, and well-thought-out features for everyday use. We take a detailed look at the technical innovations and model variants and then, in a comprehensive practical test, clarify how the top-of-the-line HSD S9i performs in real-world use – and why we don't actually want to categorize it as a typical cargo bike.
Completely redesigned from the ground up: the frame and technology of the Tern HSD Gen 3
Tern has taken the feedback of recent years to heart and thoroughly redesigned the HSD. At first glance, the e-bike remains true to its roots: it still rolls on compact 20-inch wheels, giving it an almost delicate appearance. But its inner workings tell a different story. The bike is now officially designed for a maximum permissible total weight of an impressive 190 kilograms – 10 kilograms more than its predecessor. This propels the compact bike into territory usually reserved for full-size long-john cargo bikes.
The frame itself has been significantly stiffened to accommodate this increased payload. According to the manufacturer, the front section is now six to seven percent stiffer, a difference that should be particularly noticeable when fully loaded. Furthermore, the frame and fork combination now meets the stringent EN 17860 cargo bike standard for the aforementioned 190 kilograms. At the same time, the geometry has been modernized: a longer wheelbase and a lower center of gravity are designed to noticeably improve riding stability, especially at higher speeds. The step-through height remains a pleasingly low 485 millimeters, making getting on and off the bike much easier in everyday use.
The drives: Bosch Smart System in two power levels
A significant upgrade concerns the drive system. The Tern HSD Gen 3 is now fully integrated into the Bosch Smart System. This offers advantages not only in terms of connectivity via the eBike Flow app (such as over-the-air updates and navigation), but also in terms of safety. The Bosch ConnectModule is now included as standard. In combination with a (paid) Flow+ subscription, the system offers GPS tracking, an eBike alarm, and digital locking functions – features that are almost standard for a bike in this price range these days.
Depending on the model variant, different motors are used. While the P models (P10e, P5i, and P00) are powered by the proven Bosch Performance Line motor with 75 Nm of torque and 600 watts of peak power, Tern equips the top-of-the-line S9i with a real powerhouse: the Bosch Performance Line PX. This motor bridges the gap to the CX variant, delivering a strong 90 Nm of maximum torque, 700 watts of peak power, and providing up to 600 percent pedal assistance. A positive side effect of the new motor generation: it is around 400 grams lighter, has 30 percent less internal friction, and operates significantly quieter.
For its power supply, Tern continues to rely on external batteries, specifically the Bosch PowerPack 545. A decision that seems almost bold in times of fully integrated solutions, but offers immense functional advantages.
Tern HSD: Four model variants for different needs
Tern divides the HSD Gen 3 lineup into four models, which differ primarily in the circuitry and detailed components:
The entry-level model HSD P10e (RRP 4.999,00 Euro) It comes with a TRP EASI A10 derailleur system. A special feature here is the Bosch/TRP eShift system. This electronic, wireless shifting system enables buttery-smooth gear changes under load and even offers a fully automatic shifting mode. Instead of a belt, a classic chain is used in conjunction with a Shimano Linkglide cassette, which is designed for greater durability.
For the same price, you can get the HSD P5i (RRP 4.999,00 Euro). Here, Tern uses a Shimano Nexus Inter5-E internal gear hub in combination with a quiet, low-maintenance Gates CDX belt drive.
Those who prefer a stepless translation should use the HSD P00 (RRP 5.399,00 Euro)This one is equipped with the Enviolo Heavy Duty hub, designed for high loads, and also with the Gates belt.
The spearhead is the HSD S9i (RRP 6.699,00 Euro)In addition to the aforementioned more powerful PX motor, this model boasts the new 3x3 Nine internal gear hub from Germany, which we will discuss in more detail in the practical section. Furthermore, the S9i features a Kiox 300 display (instead of the Purion 200), a higher-quality SR Suntour MobiE34 suspension fork, and a Cane Creek Thudbuster suspension seatpost.
The Tern HSD S9i in practical testing: More than just a cargo bike
Let's get down to practical matters. Before the test rides, Tern clearly positioned the HSD Gen 3 as a compact cargo bike. Looking at the pure payload figures – up to 80 kilograms on the rear rack and up to 20 kilograms at the front – there are excellent arguments for this.
Nevertheless, after our first few test kilometers, we feel compelled to slightly disagree with this categorization. The HSD is simply not a cumbersome cargo bike on roads and paths. The wheelbase is no longer than that of a regular e-bike, and its handling is superb. It rides lightly, nimbly, and incredibly fast thanks to its small 20-inch wheels. Quite frankly, this bike actually belongs in the category of the ultimate everyday and city bikes. For many riders, a cargo bike still implies a certain bulkiness. The HSD is the exact opposite. It's a normal bicycle that, if necessary, can simply swallow an unbelievable amount of luggage.
Geometry and ergonomics: One-size-fits-all.
The HSD's geometry concept is based on a one-size-fits-all approach. The frame must fit riders from 1,50 meters to 2,05 meters tall (and weighing up to 130 kg). Often, such designs are lazy compromises, but Tern has employed some clever tricks here.
For tall riders in the test (just under 1,90 meters), the setup worked perfectly. The specially developed, two-stage telescopic seatpost (with a robust 40 mm diameter for high stability) allows for enormous extension lengths. At the same time, it can be inserted far into the frame for shorter riders.
The real secret, however, lies in the slack seat angle. What's frowned upon on sporty mountain bikes these days makes perfect sense on an everyday bike. Because of the slack angle, the saddle not only moves upwards when extended, but also significantly backwards. This increases the effective distance to the pedals (for long legs) without disproportionately increasing the seat height. The result: Even with the correct saddle height for taller riders, the feet can be comfortably and flatly placed on the ground when stopped at traffic lights. This secure footing is invaluable, especially when fully loaded. Adjustments at the front are completely tool-free thanks to the variable stem, which can be adjusted not only in height but also in reach. As a family bike used by several people, the HSD is therefore hard to beat.
Motor, battery and the 3×3 Nine hub gear
The external Bosch PowerPack 545 may not look quite as elegant as a battery integrated into the downtube, but its practical benefits outweigh any drawbacks in everyday use. Anyone who leaves their bike at the train station or needs to take the battery to the office will appreciate its easy accessibility. The 545 watt-hours are perfectly adequate for a bike in this category, which is primarily designed for short trips and urban environments – even when fully loaded and on hilly terrain.
The Bosch Performance Line PX motor also impressed. With its 90 Nm of torque, it handles heavy loads with ease, reacting much more smoothly and less nervously than a classic Bosch CX. It remains pleasantly quiet and perfectly complements the bike's confident character.
The 3x3 Nine internal gear hub was the subject of much anticipation during testing. Nine gears might not sound like much at first, but its impressive 554 percent gear range easily surpasses an Enviolo and encroaches on the territory of a Rohloff hub. Combined with Bosch's eShift function, the system shifts wirelessly via a trigger. The motor briefly reduces load during the shifting process, the gear engages, and power is restored.
The shift feel is more direct and sporty than the sometimes mushy feedback of a continuously variable Enviolo transmission. The system also allows you to define a starting gear for automatic downshifting at traffic lights. There are a few minor drawbacks, however: the shifts are accompanied by a noticeable clunk, the system takes a noticeable moment to reduce torque, and occasionally, during testing, shift commands were only executed on the second press of the trigger. Nevertheless, the advantages of the enormous gear range and low maintenance clearly outweigh these drawbacks.
Easy to drive even when loaded
The braking system, consisting of Magura MT4 brakes on 2,0 mm thick brake discs, performs its function unobtrusively and reliably. The small 20-inch wheels transfer the braking power well to the asphalt. Only when the system weight approaches 190 kg and the bike is going downhill steeply are the brakes likely to reach their thermal limits. For everyday use, however, they are more than adequate.
When loaded, the HSD truly shines within Tern's accessory ecosystem. Whether it's the "Clubhouse Mini" for transporting a crate of drinks, Euroboxes on the front rack, or special transport boxes for dogs – the modularity is unmatched. Fully loaded, you naturally feel the weight. The bike becomes slightly more unstable when starting off. Those riding hands-free will notice a slight wobble in the front end from around 15 km/h. This is due to design limitations and the laws of physics, but it doesn't detract from the overall positive impression during normal riding with hands on the handlebars.
