Tern HSD – The Small But Mighty Electric Cargo Bike
In June 2011 when Tern burst onto the scene, the team already had experience running a bike brand.
Although many considered a folding bike a niche product Tern saw a future. Urban utility, and the maximization of space needed for a sustainable future, isn’t going away any time soon. As the years pass, and even since 2011, the need for small space utility will only grow. Tern saw this future but they also knew it takes more than a promise and a vision to build a company.
The Tern promise is not just great products but also great service. Like a car, there is as much parts standardization as possible. The team focused on reducing unique parts for easier manufacturing and easier after sales servicing.
With a goal of 5 years of daily use and no major service it wasn’t just parts availability that needed focus but also quality and serviceability. If you purchase a Tern product you can do so with the confidence that it will last.
The Tern HSD is a lot like the Tern GSD but smaller. While the GSD is a bike with big capacity, and a footprint the size of a standard bike, the HSD is even smaller than a standard bike.
That small size isn’t proportional with the utility though. There’s still big utility. The frame and fork of all HSD models are EFBE-tested to 170 kg (374 lb) using demanding German cargo bike standards.
Tern HSD Frameset, Sizes, and Common Features
The Tern HSD line represents three models of bikes. While the GSD lineup consists of 6 bikes and quite a bit of overlap of features and pricing the HSD is different. There are three models available each with specific details that set them apart. It’s concise and it’s easy to understand. We’ll dive in shortly but let’s start with what stays the same.
The frame, fork, and wheels remain unchanged between models. The Tern HSD, utilizes a patented, folding, 6061 aluminum design. The design has been through the EFBE Tri-test and comes away with a 170kg gross vehicle weight approval. The three modules of this test include fatigue tests, maximum load tests and overload tests – in various load cases.
It’s a series of tests designed to create a simulation of the life of the bike. Along with the bike the Suntour custom for Tern fork has also been through the EFBE testing. The fork features a 1.5″ tapered Chromoly steerer with 32 mm stanchions, a thru-axle, and 70 mm travel. Wheels are sized at 20 inches and just like the GSD it’s possible to store the HSD in an upright orientation.
Whatever HSD model you choose, expect to comfortably fit riders ranging from 4’11” to 6’5”. Adjustability is simple and wherever you fall in the range it’s a comfortable ride. At the rear move the seat post up or down and the easy-step frame design offers a comfortable upright riding position no matter your size. It also means no matter your size mounts, dismounts, and stops are easy. At the front of the bike you will find an adjustable stem.
Unique to Tern is a forged stem called The Andros. It’s a patented design that lets you adjust the handlebars up or down without tools. Set your riding position exactly how you want it in only a few seconds without any tools needed. The design uses a twin stem setup that keeps the feel light and strong as well as accommodating easy light mounting.
Besides the primary rider there is room for a passenger on the Tern HSD frame. An extra passenger could be a child or a small adult (up to 132 lb). If your passenger is still using a child seat one Thule® Yepp Maxi, Yepp Nexxt Maxi, or Bobike® GO Maxi child seat fits without adapters needed. As they grow and transition add accessories like bars, seats, wheel guards, and footrests for a comfortable ride over the years.
Other commonalities between the models include lots of accessories to make the ride the best it can be. There are hydraulic disc brakes at either end of the bike. Also at both ends are lights to keep you visible no matter the time of day. The rear light is a Herrmans H-trace featuring 220-degree visibility while the front is a 45 lux/190 lumen Tern Valo Direct. In case you need to stop the ABUS 5650L integrated frame lock, keyed-alike with the battery, adds extra security.
Tern HSD Models
As I said above the HSD model lineup is concise and easy to understand. There is one additional wrinkle though. In the US there is a brand-new model. If you are browsing the site outside of the US it’s unlikely you will even have access to the information about the new model. The HSD 11 is the first class-3 electric bike from Tern and it slots in as the second model from base in the Tern lineup.
The HSD S+ represents the top of the line that Tern offers. Although there are many features shared between models each model in the lineup has a few features that set it apart. The brakes on the S+ model are Magura MT4, hydraulic disc with a 180 mm front rotor and a 160mm rear rotor. Instead of a chain there is a Gates Carbon Drive CDX belt. And finally, below the saddle there is a Cane Creek Thudbuster ST, Tern Telescope, 34.9/30.9 mm.
Those are the small details but the drivetrain is what is truly special about this bike. The S+ comes with a 500wh Bosch powerpack as well as a Bosch Intuvia display. The motor that powers this system is the Bosch Performance (Gen 3) which has a max speed of 25 kph (EU)/20 mph (US).
The specific Bosch motor isn’t listed anywhere however it can only be the Performance Line Cruise motor given the 20mph max top speed. That puts max available torque at 65Nm and max pedal assist at 300%.
The Bosch Performance line represents the top-of-the-line models meant for street bikes. The Performance CX motors are higher in the model lineup but aren’t designed for us outside of mountain bikes. The Performance Line cruise features 4 available pedal assist modes, a maximum cadence of 120rpm, and weighs ~7.1 lbs.
Aside from the electric motor system being top-of-the-line the shifting is the other really special piece of the Tern S+. Instead of manual shifting the S+ utilizes the Enviolo AUTOMATiQ system. The Enviolo stepless drivetrains are already one of the best options on the market however the AUTOMATiQ takes it even a step farther.
The system is stepless and shifts under load without issue. It’s also completely automatic and utilizes a cadence sensor to hold a consistent cadence no matter the environment.
The Sportive system used in the Tern S+ features a high-powered shift motor and three available rider profiles. There is an available gear ratio range of 380% and customization is available via a Bluetooth connected smartphone. At the end of the day what this system really represents is a simpler rider experience. Focus on your cargo, your environment, and your passenger while you let the bike take care of everything else.
Tern HSD S8i
The next model down from the S+ is the Tern HSD S8i. The S8i is a less revolutionary bike in some ways but that doesn’t mean it’s not a top-of-the-line bike. The featured motor is a Bosch Active Line Plus instead of the Performance line found in the S+. The Active Line is lower in the Bosch lineup but it still features torque sensor-based rider input.
Using a torque sensor makes for a more natural feel in an electric-assist bike.
Because the bike understands how hard you are pedaling, as well as how fast, additional power feels more like a gentle push. Top speeds remain the same 25 kph (EU) and 20 mph (US) but maximum torque sees a reduction to 50Nm and max assist falls to 270%.
Depending on what hills you experience, as well as how much weight you have on the bike, that might mean more pedaling. The smaller 400Wh battery might also mean more pedaling if you need to stretch the available distance average of 36 miles.
Instead of the Enviolo system found in the S+ the S8i makes do with a more conventional Shimano 8 speed rear hub. The Shimano system does not feature electronic shifting however it is a widely used, tried and true, workhorse system. Expect a long service life and smooth, reliable, shifting even under load. A Gates Carbon belt drive still means no worries about getting grease on your pants.
The S8i also sees a move to a traditional, non-suspension, seatpost instead of the Cane Creek Thudbuster.
Tern HSD S11
If you are outside of the US this model isn’t on your radar. However, for those in the states the S11 represents the first Class 3 electric bike from Tern with a top speed of 28mph. In many ways the S11 is actually a mix of parts from both the high and low end of the HSD model range but what really sets it apart is the motor.
Getting up to the 28mph top speed is a job for the Bosch Performance Line Sport motor. It’s a motor that features four support levels ranging from 55% up to 300% and available max torque of 35Nm up to 65Nm. It also is not offered in a hub-based system and only works with a derailleur.
When it comes to city bikes a Gates Carbon belt is absolutely an upgrade compared to a chain and derailleur. It’s the lack of support from Bosch that dictates the chain on the Tern S11 and has it feeling like a step back compared to the S+.
If you want the 28mph top speed then you are going to be using a chain and derailleur but that doesn’t mean it has to be a low-end system. The Tern S11 utilizes Shimano XT components which slot in just below the top-of-the-line XTR in the Shimano lineup.
Many people consider XT the best mix of price and performance available and there’s very little reason for moving up to XTR. Gearing is an eleven-speed system with 11-36 rear cassette.
The Cane Creek suspension seat post makes another appearance on the S11 as do the Magura hydraulic disc brakes. The battery is a 500Wh unit which Bosch conservatively rates at a 44-mile range.
Tern HSD P9
The final model in the Tern HSD lineup is the entry-level P9. There are some drivetrain compromises to make a more affordable option. Keep in mind though that we aren’t starting with low end parts and then cutting costs. The Tern HSD uses some of the best components on the market. The P9 is still using top of the line pieces even though the motor and drivetrain are a little more affordable.
The drivetrain comes from Shimano and the Alivio product line. It’s a chain and derailleur system with 9 speeds and an 11-32T cassette. Alivio is lower in the product offerings from Shimano. Keep in mind though that with a quality pedal-assist system the number of gears is less important.
The Bosch electric system is still present and still one of the best available. In the P9 the Bosch Active Line Plus (gen 3) system is the available option. Paired with the motor is a 400Wh battery.
Brakes are still hydraulic with a 180mm front rotor and a 160mm rear. This time it’s a Shimano system instead of the Magura found in the other HSD models. The seat post is also a standard, non-suspension option. It’s worth mentioning though that adding the suspension seat post would be an easy upgrade.
- Consider also: Tern GSD series
Assembly and Delivery
Tern offers some bikes for sale directly through their website but it’s not as simple as it might seem. All Tern bikes sell through dealer partners. Even if you are able to purchase directly through the Tern website a Tern dealer is the one who will be handling your order.
A dealer that is close enough to you then direct pickup will mean a fully assembled bike. It is possible to order Tern bikes for shipment though. not all bikes who use a dealer network allow that arrangement but Tern does. If you have the bike delivered it will arrive in a box, like other bikes, however, given that it’s a folding bike it requires even less assembly.
Tern bikes fold and that means the handle bars can stay fully assembled when shipped. Similarly, wheels are ready to go as well. The only items that need installation are the pedals and any accessories. If you order any of the many accessories Tern sells, they will come in a separate box.
Tern wants to be there to show people that it’s possible to replace a car with a bike. They represent utility and functionality. Just like with cars some people need more utility than others. If you need to carry the most possible cargo, or you have multiple passengers then the GSD is your choice.
On the other hand, if you are a smaller family or you think you might need a bit less cargo then the HSD is a great fit. It’s even smaller and more small space friendly than the GSD but there is still tons of utility.