Tern GSD S10 review: An electric cargo bike that can replace your car
The Tern GSD S10 redefines what an e-bike can do – who needs a second car when you’ve got a GSD?
Pros
- Great for carrying very heavy loads of cargo and smaller people
- Huge range of carrying accessories
- Stores vertically
Cons
- Very heavy (44.2kg as tested)
- Expensive, especially with the double battery option
Tern specialises in making compact and folding bikes and e-bikes, and the GSD range is its premium cargo model. It can carry big loads and up to two small passengers (or one larger one) and the latest version has genuine performance upgrades such as a self-locking double-sided kickstand and Bosch’s most powerful motor.
It’s undoubtedly pricey, but the huge carrying ability it offers means it’s a truly practical alternative to a car for short journeys, especially given how fast the cost of owning a car is rising.
Tern GSD S10 review: What do you get for the money?
The unique part of the GSD is the long rear frame. It looks as if a conventional bike frame has been squashed down and the rear half stretched out. It’s extremely strong-looking with oversize tubes and some lattice construction for extra strength.
Foot rails come as standard along the length of the rear rack, allowing you to take one or two passengers up to a maximum of 80kg – via the optional child seats. There are also optional and wider “Sidekick” attachments to the footrests to provide more support for bulky loads in pannier bags or for passengers to more comfortably rest their feet. My test bike came with this “Double Wide” option.
The GSD uses 20in diameter wheels, a standard but relatively small size for a bike. This size makes a lot of sense here, though, as it helps to keep weight near the ground, making for more balanced and predictable riding.
The electric assist system comes from market leader Bosch in the form of the Cargo Line mid-drive motor. This is the firm’s most powerful motor and is not seen on that many e-bikes. It boasts up to 400% motor assistance to the pedal cranks (ie, 4 x your pedal input), with power kicking in once you start pedalling.
There’s space on the bike for two Bosch PowerPack batteries, but one will suffice if you only do short trips. The GSD S10 comes with a 400Wh battery as standard. That’s a relatively small battery for such a heavy e-bike so, if you plan to be out riding all day, a second 500Wh battery as an optional extra might be a good idea to give a huge 900Wh capacity.
READ NEXT: The best exercise bikes you can buy
Batteries are covered by Bosch’s battery guarantee promising a minimum of 60% of full charge capacity for two years or 500 charge cycles (whichever comes first) – although if you look after your battery properly it should last much, much longer.
I tested the most “basic” version of the GSD – others come with stronger hub gears and more battery capacity – but all share the same hugely strong wheel construction and Magura four-piston hydraulic disk brakes (two pistons is the norm on most e-bikes).
In addition to all this, the GSD comes with an impressively powerful Ignis headlight and RearStop brake light, plush Suntour front suspension, full chainguard and mudguards, promising to deliver a comfortable ride in all weather conditions.
Tern GSD S10 review: What can the Tern GSD S10 do?
In a couple of ways, the GSD S10 is similar to ride to the recently reviewed Raleigh New Motus Tour Plus (£2,495), which also uses a Bosch motor system. Power it up using the Purion display, select your assist level and you’re ready to pedal away, up to the maximum legal assisted speed of around 16mph. It’s very intuitive and straightforward.
Like the Raleigh, the Tern is also comfortable to ride. The one-size frame has a backwards and forwards adjustable handlebar, and the raked, telescopic seatpost means there’s a huge amount of adjustment for different rider sizes. Tern says it will suit riders between 4ft 11in and 6ft 5in. The large-volume tyres, front suspension, comfy saddle and upright riding position make it easy to ride and it feels safe and stable, even at speed – no doubt the very long wheelbase helps in that respect.
So far, so very much like other high-performance, well-designed e-bikes. Where the GSD comes into its own is when you start to put extra loads on it, or attach them to it. Big shop? No problem. Two small toddlers to take to school? Child seats are available. It’s raining – I can’t go, can I? You can if you have Tern’s Storm Shield weather housing. You get the idea. There doesn’t seem to be a carrying scenario not catered for within Tern’s wide range of accessories for the GSD.
Initially, I tested the bike out with two large Tern Cargo Hold 52 panniers. These swallowed a monthly shop with no problems, 45kg distributed between the enormous Cargo Hold 52 rear panniers and 20kg of rice on the front rack (yet another optional extra).
I also took an adult passenger of 95kg on the rear and managed fairly comfortably on a ride using bike paths and quiet roads. Tern says the maximum rating of rider and cargo (human or otherwise) is 200kg, but that rear load shouldn’t be more than around 80% of rider weight. As I am 70kg I exceeded this guideline by quite some way so the steering felt fairly light – but rather vague handling aside, the GSD managed with ease. Had I thought of it, a counterweight on the front rack would have been a good idea.
If you want to carry really mammoth loads the GSD also comes with a trailer mounting point at the rear of the frame that will take common bike trailer hitches from Thule, Burley and Weber without the hassle of needing special adapters (that can be a problem with other bikes where the trailers mount directly onto a rear axle).
The above method of trailer towing has a limit of 53kg – presumably that’s the maximum the hitch mounting will stand with a one or two-wheeled trailer in tow. However, I was lucky enough to try out the remarkable Carla Cargo trailer on it. This has a massive 200kg load rating and there’s a special mount available so its tow ball hitch can be mounted to the top of the rear rack. You won’t be able to use the top of the rack for anything else while the trailer is in use, though.
As the trailer has three wheels and independent brakes it makes for a very smooth ride, and the Tern GSD was able to easily tow up to 150kg of building material on it – even up fairly steep hills, proving the Bosch Cargo Line motor is up to just about any task you care to give it. The Carla Cargo is a whopping £4,000 and is really aimed at business use but it does show what the GSD is capable of.
Even with such heavy loads, handling is always assured. The bike has a low centre of gravity, a long wheelbase and big volume tyres that all work in its favour, even when going at speed. The four-piston hydraulic brakes were about the most powerful I’ve ever tried on an e-bike but aren’t overly sharp. The ten derailleur gears helped the bike make it up every Pennine gradient I pointed it at, too.
With so many loading possibilities it’s even more difficult than normal to tie down battery range. I estimated the 400Wh battery would give a range of around 30 miles with a very light load but half that with a heavy trailer in tow. Upping the capacity to 900Wh gives estimated figures of just under 70 miles in light use and 35 miles in very heavy use.
The GSD has one more very neat trick up its sleeve. When not in use it can be stored on its end and, with the handlebars folded down to minimise its footprint, its “folded” size of 176 x 40.5 x 83cm can be very effectively tucked vertically out of the way.
READ NEXT: Are e-scooters legal in the UK?
Tern GSD S10 review: Should you buy it?
There’s no other e-bike out there quite like, or quite as capable as, the Tern GSD. Yes, it’s a considerable investment and, once you add on any accessories you might want, you’re talking enough cash to buy a decent second-hand car.
But compare the running costs of motoring and the likelihood of being stuck in traffic with the exercise and sheer fun you get from using the GSD and I know which option I would choose.