Tern Vektron P5i

The Tern Vektron P5i is a high quality folding e-bike that can carry a lot of stuff, and folds simply and reliably into a small enough package that it’ll easily fit on a train luggage rack or into the boot of a car. It rides well, and fits a good range of rider sizes from its single frame size. Only its weight and the mediocre range from the standard battery really let it down.

Tern Vektron P5i – build and spec

We’ve reviewed the Tern Vektron before, more than once, and the last review by Richard Peace is of essentially the same design. The single size alloy frame is chunkily built and there’s a custom rack bolted to the back with a generous 27kg capacity. The 20” wheels are shod with Schwalbe Big Apple balloon tyres and you get full mudguards and integrated lighting.

A Bosch Performance Line motor takes care of propulsion, and there’s a Smart System remote and an Intuvia 100 display on a single-arm mount that feels a little fragile. The battery (400Wh as standard, our review bike had the bigger 545Wh unit) sits low behind the seatpost. Tern uses its clever adjustable Andros stem at the front which makes it easy to adjust the reach, and there’s a telescopic seatpost to accommodate riders of all sizes.

The difference with the P5i to other models we’ve reviewed lies mostly in the drivetrain. This is a belt drive bike, running a Shimano Nexus 5 hub gear that gives a 263% gear range through five evenly spaced gears.

Generally when a bike has a belt drive, it needs a separable frame, because the belt passes through one side of the rear triangle, and you can’t achieve that with a one-piece belt: something has to give. That’s not the case here though: the belt goes up and over the chainstay via a roller, so it’s removable without needing to have any gap in the stays. It’s a neat solution, although it does add a bit more tension into the drivetrain as a whole, which means the pedals don’t spin very freely. It’s not an issue when you’re riding under power though and realistically, on a bike like this, that’s all the time – unless you misjudge your range.

Tern Vektron P5i – motor system

The belt is driven by a Bosch Performance Line motor which puts out 75Nm of torque and is whisper quiet. For a standard city bike – i.e. not one you’re hauling massive loads on – it’s more or less my favourite motor: plenty of grunt, good reliability, barely any noise.

I’ve generally found it to be a pretty efficient motor too, although I’d say that’s tempered by the drivetrain: belts and hub gears are measurably less efficient than chains and derailleur gears.

It offered plenty of power to haul me and my shopping up the fairly long and steep hill back to my house (1.5km at 5%, with a 12% steep bit) without ever feeling like I was having to put in too much of my own effort. Unloaded, I didn’t even need to drop down to first gear.

At the other end of affairs, the top gear is plenty big enough for anything you’re likely to do on a bike such as this, and while the evenly-spaced gaps in the gears are fairly big, it’s never an issue. The five-speed hub is less finicky about setup than its 8-speed sibling, so it’ll barely ever go out of whack and the twist-shifter is easy to use, even if the action isn’t the lightest.

Tern Vektron P5i – the fold

The Tern Vektron fold is a fairly classic one: the steerer folds down and there’s a big hinge in the middle of a frame to fold it essentially in half. Once you’ve done that you can use a rubber strap under the main frame tube to hold the bars captive, and the two halves snap together with magnets. Those magnets are absolutely not strong enough to keep the whole thing together as a neat package when you’re lugging it onto a train or into the boot of a car; I’d recommend carrying a ski strap or similar to hold the two halves together if you know you’re going to be folding the bike up as part of your ride.

The bike has one removable pedal on the outside of the fold which it’s sensible to take off if, for example, you’re laying the bike down on a train luggage rack. The cables and wires fall sensibly most of the time too, although I did manage to pull the wire out of the remote on a couple of occasions. This is simple to fix, but not ideal.

When it’s folded, the bike will sit on its end thanks to a foot at the bottom of the seatpost, and you can also roll it around on its wheels, which is a lot easier if you extend the seatpost to use as a handle.

It’s fairly easy to manoeuvre, but at over 21kg it’s not a light bike. I found I could fold it and lift it up and down stairs, but generally when travelling by train I only folded it to get on and off, and kept it unfolded the rest of the time and used the station lifts – and I’m a fully fit 100kg man. If you’re slight of build or you have any mobility issues or muscle weaknesses, you may struggle hauling the Vektron about. You can remove the battery to make the bike lighter to lift, but it’s still not going to be a featherweight.

Tern Vektron P5i – the ride

The Vektron rides a lot like a full-size city bike. There’s never a moment when either of the folding mechanisms exhibits any play, and although it’s a reasonably short wheelbase and a smaller wheel size, it rolls effectively and doesn’t feel unstable at all, thanks partly to the weight being kept nice and low.

I’m very much at the top end of the height range for the Vektron but I didn’t feel cramped by the position, and my wife who’s significantly shorter than me found it comfortable too.

The big-chamber tyres can be run at fairly low pressure and they certainly take a bit of the sting out of poor road surfaces, as well as providing decent grip. The bars are wide enough to make steering uncomplicated and the Ergon grips are very comfortable. The Magura brakes are very good, with plenty of power and a really nice feel.

Overall, the whole bike feels solid and behaves in a very neutral way, and there are no real foibles to pick up on. Some folding bikes feel a bit compromised in the ride, especially for a bigger rider like me. Not this one: it’s a genuinely pleasant bike to be aboard. The frame design makes getting on and off easy too: the small wheels and low-step single tube design make stepping into and out of the bike very easy.

Tern Vektron P5i – range

Realistically, you’re not going to be buying a bike like this to go on big adventures: it’s designed for short-distance use and the saddle shape reflects that: big and wide for quick trips. Nevertheless, I’ve ridden it from Bath to Bristol (about 25km) and it was fine over that kind of distance.

Even with the 545Wh battery, and using mostly the second-most-frugal Tour mode, I’d have struggled to ride it back home again without running out of juice on the final climb. I found that the belt-and-hub combination on this bike gave me a bit less range than I’d expect from a Bosch system: there’s a fair bit of friction in the belt and a hub’s not as efficient as a derailleur setup, so that’s probably to be expected.

The practical upshot is that you’ll be charging this bike more often, especially with the standard 400Wh battery, but it’s unlikely to be a major issue unless your mixed commute includes 40km or so of riding. The range is fine for the purposes the bike is designed for, but it’s worth knowing that it’s not as good as some others you could choose.

Tern Vektron P5i – carrying capacity

You can carry a lot of stuff on the Vektron. The Atlas V rack is mounted to the frame at eight points and has a 27kg capacity, so enough for a weekly shop in some big panniers, or a reasonably-sized child in a seat.

You can fit a Thule Yepp Maxi or Dash RM child seat without adaptors, and the rack is also compatible with KLICKfix, Racktime SNAPIT 2.0, and Ortlieb Quick-Lock 2.1 & 2.2 systems, so you can fit a range of bags, baskets and accessories to the top of it from Tern’s own range, or from third parties.

There’s a mounting point at the front too, which means you can add Tern’s Luggage Truss (max load 7kg) which gives you a KLICKfix mount at the front for even more capacity.

Tern Vektron P5i – value and overall

At £3,800 the Vektron P5i is a pretty expensive folding bike but I’d say that overall it’s more like a useful city bike that’s nice to ride and comes with a large capacity for carrying things, and the fold just makes it more versatile.

I’ve got a Tern GSD in the shed and at no point during testing did I feel like I needed the bigger bike for any reason other than that it was easier to use for shopping because the panniers were already fitted.

I’m past the point where I’m ferrying kids around all that much (although Joel at 18 and over 2m tall still likes a lift into town on the GSD) so realistically I could probably downsize to a smaller bike now. Maybe I wouldn’t go this small, but I probably could, and the fact that it folds would certainly be handy.

There are certainly lighter and more compact e-folders out there, for example the Velo de Ville E-Foldy, and there are plenty of good quality folders that are cheaper: the UTO PRO20 (formerly the Eovolt Afternoon Pro) comes in under three grand, and the MiRider 20 with Efneo’s clever 3-speed motor is a similar price (we tested the single speed version).

We’ve reviewed plenty of cheaper folders that have done well too: the Pedibal Navigata and the Ampere Alter, for example – both of which are fine for lighter use, but don’t have the build quality of the Tern or the grunt of the Bosch motor.

You’re getting what you pay for here: I wouldn’t say the Tern is great value but I wouldn’t say it was necessarily overpriced either. If you’re looking for a capable city bike for everyday use, that can carry a good load and also folds for mixed-mode use, then the Vektron is easy to recommend if you have deep enough pockets for it.

> Best folding e-bikes – our favourites from those we’ve ridden (and folded and unfolded)