Tern GSD long-term review: Small in stature, big on capability

At any given moment, I have a number of high-end road, gravel, and mountain bikes at my disposal. But here’s a secret: my favorite bike is my family e-cargo bike, purely because of the way it affects my day-to-day life.

And so it was with an unusual amount of enthusiasm that I greeted the Tern GSD, a clever e-cargo bike whose designers had seemingly thought of everything. I spent several months — and hundreds of kilometres — on it, and came away very impressed, but not quite 100% sold.

Every year at the Eurobike trade show, I’m asked the same question by industry friends and acquaintances in attendance: “What’s the coolest thing you saw at the show?” After nearly 14 years at this gig, usually the answer in my head is “Not much.” But at the 2017 show, one bike caught my eye in a big, big way, and I told everyone who would listen.

You see, I have a thing for cargo bikes, specifically the e-assist kind. Ever since spending a month (January, mind you, in Colorado) car-free on Trek’s Transport+ in 2011, I’ve been wholly sold on how much that sort of vehicle would impact my day-to-day life. After dabbling with a few more, I eventually bought my own e-cargo bike (a Yuba Spicy Curry) in 2016. Roughly 10,000 kilometers later, it’s arguably the most frequently used vehicle I own.

The Tern GSD is one of the most unique utility bike I’ve come across. Much of it is absolutely brilliant.

As much as my wife and I love it, though, it’s far from perfect. The Currie Tech mid-drive motor system is quirky, to put it mildly, the battery life isn’t great (especially with this many hours on the clock), and the long tail frame layout takes up a lot of room.

But this Tern … it seemed to be everything I was looking for. It was the first bike I’d genuinely lusted after in years.

Enticing specs, brilliant design

For as long as I can remember, I’ve admired things that are designed with space efficiency in mind, and this GSD ticked that box big-time. Tern is well-known for its expansive range of folding urban bikes, and the company utilized a lot of that experience for its first-ever cargo bike.

The compact aluminum frame is built around diminutive (but wide) 20in wheels and tires at both ends, which yield roughly the same wheelbase as more traditional cargo bikes, but an overall length nearly on-par with standard townies or cruisers. The folding stem and dual-stage telescoping seatpost quickly cut the height of the GSD almost in half so the whole thing can roll into the back of many SUVs. Standoffs at the rear of the frame allow the whole thing to rest vertically for storage.

When properly outfitted, the Tern GSD can carry a ridiculous amount of stuff.

Interestingly, Tern offers the GSD in a single size, claiming the telescoping seatpost and adjustable handlebar have enough range to accommodate rider heights from 1.50m to 1.95m (4ft 11in to 6ft 5in). That’s a big plus for families where multiple people are likely to be sharing the same bike.

The GSD may be highly space-efficient, but it still packs a big punch.

Tern quotes the maximum cargo capacity at a whopping 200kg — rider included — spread out between the expansive rear rack and optional bolt-on front rack. The rear rack accepts up to two of Yepp’s popular range of child seats, optional double-sized panniers each fit a pair of typical grocery store bags, and there’s also a wide range of other GSD-specific accessories to expand and tailor your hauling needs to suit.

The integrated rear rack is positively huge, with plenty of room for two baby seats. Tern also offers a big bolt-on parcel shelf if you’re mainly just carrying packages.

Want to carry two kids, or one baby and a toddler? No problem. Big boxes? Have at it. Tern even says you can give another adult a lift on the rear rack when properly equipped, and all of that cargo is positioned comparatively low to the ground, thanks to the 20in wheels.

Not that anyone riding a GSD has to push all of that mass using only their own quads, mind you; this is an e-bike, after all. Down below is a powerful and reliable Bosch Performance Line mid-drive motor (250W, 63Nm), whose generous range can be extended all the way to 250km (155 miles, claimed) with an optional second battery.

Tern equips the GSD with a smart build kit, too.

On my GSD S10 model, drivetrain duties are handled by Shimano’s workhorse Deore clutched rear derailleur and trigger shift, coupled to a 10-speed 11-36T cassette, and Magura supplies powerful four-piston MT5 disc brakes at both ends. The rolling stock is more interesting, built with thru-axle house-brand cartridge bearing hubs, 36mm-wide (external width) aluminum rims, but with an extra-wide 36mm internal width and meaty 2.4in-wide Schwalbe Moto Super-X reinforced semi-slick tires.

The 2.4in-wide tires offer plenty of grip, and the highly reinforced casings are impressively tough. The standard front and rear fenders are a nice touch.

If you’ve got a little more cash to burn, there’s also the more upscale GSD S00, which features a torquier Bosch Performance Line CX motor, an Enviolo continuously variable rear hub transmission, plus a pair of cargo panniers and a wheel lock stock (both of which are optional add-ons on the S10).

Either way, front and rear fenders come standard, as do front and rear lights, a bell, a chainguard, and a dual-leg kickstand.

Claimed weight for the stock setup with a single battery is 27.06kg (59.66lb); my sample with the dual-battery setup and a set of panniers is a hefty 33.79kg (74.50lb). Retail price for the standard GSD S10 configuration is US$4,000 / AU$6,650 / £4,000 / €4,100.

Getting things done

This was a somewhat unusual bike test for me, not so much for the three-month test period on the primary sample, but the fact that I also rode three different GSDs over a longer period of time: the extended-loan sample here at home, another company demo at the 2018 Sea Otter Classic, and yet another company demo at last year’s Eurobike trade show.

First, the good news.

Tern obviously makes some big claims when it comes to the GSD’s hauling capabilities, and I’m happy to say that they seem to bear out. Much of my time with the GSD was spent shuttling my 5yo daughter around town, often with varying amounts of groceries and other items. On another day, I did a 32km (20mi) round-trip to our local Costco warehouse store, returning with both panniers and my camera backpack loaded to capacity, and still had 4/5 bars remaining on the battery gauge despite the distance and nearly 300m (1000ft) of total climbing — and that was with the motor on the second-highest power setting.

The generous range makes the GSD useful for far more than just errands in town.

On one chilly day in December, I hauled a giant plastic bin full of our podcast gear 21km to Pearl Izumi’s headquarters and then another 21km back. I unfortunately had forgotten to charge the thing, so I started with barely 2/5 bars left on the battery meter. But even with all of that weight and 300m (1000ft) of total climbing that day, I still had (some) power to spare by the time I got back home.

For three consecutive days at the 2018 Sea Otter Classic, I used a different dual-battery GSD S10 for the 55km (34mi) round-trip to and from the Laguna Seca raceway, with panniers packed with my camera gear and a bunch of extra clothing (not just for me, but also for co-workers Caley Fretz and Neal Rogers). Even with 600m (2000ft) of climbing each day, I didn’t even bother to recharge the thing each evening, and still had plenty of battery power to spare.

As icing on the cake, I used a third GSD S10 to go back and forth from the Eurobike trade show to our condo — a mostly flat route covering about 23km (14mi) round-trip. On the last day, I shuttled all of my luggage (and all of packrat tech writer Dave Rome’s luggage) with ease.

Unlike Tern’s other folding bikes, the GSD doesn’t fold in half lengthwise. Instead, it collapses in height, which allows it to fit (upright!) inside many SUVs and vans.

And yes, I did even verify Tern’s claim that the GSD would fit inside a reasonably sized SUV. It was a tight fit, mind you, but with the stem folded down and the dual-stage telescoping seatpost crammed all the way into the frame, it was no problem rolling the bike into the back of a late-model Toyota Highlander.

By the time I finally had to give it back, I had ridden the GSD for roughly 650km (400mi) — not a huge number in terms of total distance, but about a hundred rides overall, and more than enough to get fully acquainted with its nuances.

Throughout it all, I never suffered a bit of range anxiety, and even had I had a single battery setup instead of the ultra-conservative dual-battery one, the GSD S10 would have easily suited my needs. I did notice some discrepancy between the claimed range and what was displayed on the Bosch computer, though.

There are four assist levels on tap here — Eco, Tour, Sport, and Turbo — but the biggest number I ever saw on the screen after a full charge was 212km (132mi). On Turbo mode, the claimed range was 76km (47mi). Those are still big, big numbers, but nevertheless a bit shy of the claimed figures.

Tern supplies the GSD with a single Bosch battery, but you can fit a second one if you need or want more range. Unless you’ve got a really long way to go, though, you’re unlikely to need to spend the money.

The standard Bosch Performance Line motor packed more than enough power, though, even heavily loaded on the 14% grade leading into the Sea Otter venue. And short of a couple of very minor complaints (such as the somewhat mushy shifter feel and minimally supportive saddle), the workhorse build kit was perfectly adequate.

For all intents and purposes, this worked nearly as well as my car for primary transportation, both in-town and elsewhere.

Flies in the ointment

I had high hopes of replacing my trusty Yuba with the GSD, and I went into the review fully anticipating that I’d end up asking the folks at Tern for an invoice instead of a return shipping label. But alas, there were a few things about the GSD that I just couldn’t quite get over — at least not enough to justify me making the switch.

First and foremost, the dual-20in wheel format is just plain odd in terms of handling. I’m a big fan of 20in rear wheels when it comes to cargo bikes, as it greatly lowers the center of gravity and helps keep the total overall length within reason. On the GSD, the small front wheel helps the bike feel remarkably nimble in urban situations, but it also feels pretty sketchy at more moderate speeds.

Despite the unsual appearance, the Tern Andros stem is very rigid with nary a hint of flex in the tall aluminum mast.

Despite the low-slung profile, frame stiffness doesn’t seem to be the issue here, as there’s ample reinforcement throughout. Based on previous experience with other Tern folding bikes, I blame the 20in front wheel. Stability just is not its forte, which is especially unnerving when your kid is riding out back.

Making matters worse, the GSD almost requires that you keep both hands on the bars, as you otherwise get some fairly serious speed wobble, even when the bike isn’t loaded.

I also took issue with the riding position. Personally, I found the seat tube angle to be a little too slack, and the cockpit length far too short. That sort of packaging undoubtedly helped Tern keep the GSD’s overall length within reason, but I would have happily traded that compactness for a longer and more stable-feeling front end.

Granted, it’s likely Tern chose to compromise the GSD’s dimensions in order to accommodate a wider range of rider heights, but at 1.73m (5ft 8in) tall, I’m about as average as can be, and the GSD just felt a little too small for comfort.

The dual-stage telescoping seatpost helps the Tern GSD supposedly accommodate rider heights from 1.50m to 1.95m (4ft 11in to 6ft 5in).

One other small thing: when compared to the GPS-based Wahoo ELEMNT Bolt, the Bosch computer consistently registered speeds that were about 1.5km/h (1mph) faster. Whether that had an impact on the stated range is unclear (not that it ever mattered, since the range was so generous already), but given that e-bike motors are generally required to cut out once they reach a certain speed, it was a little bit of a bummer to lose that assistance sooner than I should have.

Fantastic for urban settings, but compromised elsewhere

I couldn’t help but feel like the GSD was a little … confused. On the one hand, its compact size and nimble handling make it a joy in urban settings: it’s easy to maneuver, easy to park, easy to store. In many ways, I saw it as the two-wheeled equivalent of the classic European van in that it has a tidy footprint, but yet is still immensely capacious.

If you live in an apartment (and assuming you’ve got an elevator if you don’t live on the ground floor), or if space is generally at a premium, I can think of no other cargo bike I’d even remotely consider buying.

You might not be going all that fast on the Tern GSD on a regular basis, but depending on how you have it loaded up, it helps to have seriously strong brakes to bring all that mass to a stop.

But that said, the GSD’s generous range and carrying capacity also make it well suited to longer trips where you might otherwise be tempted to use a car. But in those situations, I constantly found myself wishing I was on a bike with greater stability. Compact or not, that 20in front wheel is just too squirrelly for my liking, and I just never grew accustomed to the nervous feel.

I really wanted to love you, GSD, but that initial lust I felt unfortunately faded into the reality that I just didn’t want to spend a lifetime together with you. Don’t feel bad; you’ve got so, so much to offer, and I’ve no doubt that there are plenty of people who will form a long and lasting relationship with you.

It’s not you, GSD, it’s me. Can we still be friends?

www.ternbicycles.com

Photo gallery

Whereas most cargo bikes opt for two standard-sized wheels, or maybe just one smaller wheel (depending on the format), the Tern GSD goes with 20in wheels front and rear. The concept offers advantages in terms of packaging, but definite disadvantages in terms of stability.

The small footprint and tremendous capability makes the GSD an easy pick for people living in urban environments where a more conventional cargo bike might be too cumbersome.

Suffice to say, the standard Bosch Performance Line mid-drive motor packs plenty of punch for most situations.

The low-slung frame makes for easy mounting and dismounting, yet overall frame stiffness seems surprisingly good thanks to the ample reinforcements.

The Bosch Performance Line mid-drive motor produces plenty of power and torque. But if you want more, the higher-end GSD S00 model includes an even torquier Bosch Performance Line CX motor. Aside from a bit of buzziness, the motor runs quietly and kicks in seamlessly.

The computer is easy to use and the display is highly legible.

The hinge mechanism is brilliantly designed, with an integrated safety lock and a rock-solid clamp.

Mounts on the head tube accept an optional front cargo rack if you need additional carrying capacity.

The bolt-on side rails help with parcels, and also serve as footrests if you’re carrying passengers.

Getting … things done.

Up top, double quick-releases and a neat pivot mechanism allow for some height, length, and angle adjustment to the bar and stem. It’s a system that was originally pioneered by German company Syntace.

The clamps conveniently leave space in between for an integrated front light. I would have liked to see a flashing setting, but you can only choose between a steady on and off. That said, it’s reasonably bright, at least for slower speeds.

The Tern Cargo Hold panniers are truly massive, and their squared-off shape makes that space extremely usable.

Most cargo bike panniers are basically just big bags. These are the first ones I’ve come across that have some shape and structure to them.

The 20in wheels also help keep the center of gravity of whatever you’re carrying on the GSD very low.

The optional side bars also lend some support to the bottom of the Cargo Hold Panniers.

Such a little widget might seem silly on a regular bike, but it’s quite handy to have the front wheel held steady when you’re loading things up.

Multiple anchor points allow you to adjust the bag to suit the contents.

The Shimano Deore clutched rear derailleur is a solid choice, providing reliable performance and excellent chain control.

The Magura MT5 levers are nicely shaped and feel reasonably firm in your fingers. Don’t get too excited about the brass bell; that’s a personal add-on.

The wheels may be small, but the tires are very wide and impressively fast-rolling – just the thing for urban use.

Tern specs thru-axle cartridge bearing hubs front and rear.

The stock pedals have lots of grip material on them, but they’re not all that grippy.

The Ergon grips look a little funny, but they’re actually very comfortable to hold.

Early examples of the Tern GSD included this dual-leg kickstand, which was woefully inadequate for the job. It’s thankfully been replaced with a different dual-leg design that’s far sturdier and more stable.

A small handle is molded into the back of the stock saddle for impromptu passengers. It’s minimal, but gets the job done (barely). The saddle itself doesn’t offer much support, though, and is best suited for short trips.

A single bottle mount is situated on the top tube.

The chain runs a little too close to the chainstay for comfort. It runs quietly most of the time but is still prone to rattling on rougher roads.

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