2021 Tern Vektron Review

By Erica, G&O Mechanic since November 2018

I became the happy owner of a 2021 Tern Vektron S10 in mid-November 2020, after months of dithering over my various options of e-bikes. I wanted to share my experience with this bike, now with over 500 miles of use!

Why the Vektron?

I use my Vektron primarily to commute 7 miles each way to work at G&O, and occasionally for errands and recreation. I chose the Vektron for a few reasons:

1. My current apartment is located at the top of two long flights of stairs, one to reach the house from the sidewalk, and another flight inside the house. There's also a tight 180 degree turn at the front door to go up the stairs, which challenges any regular bike. First and foremost, I needed something I could physically maneuver into my place! Most e-bikes weigh above 60 pounds, but the Vektron is just under 50 pounds.

2. I have no garage or other protected external storage. The bike has to be stored inside my house, whether the day is sunny and dry or pouring rain. Reaching our storage closet normally involves taking a bike through the whole apartment, over carpet. In contrast, I can keep my Vektron folded near the top of the stairs without it getting in the way of daily life.

3. I wanted a mid-cost electric bike with a Bosch motor. The 2021 Tern Vektron S10 retails for $3,699, and having worked on bikes with Bosch systems for over two years now, including dozens of Tern bikes, I know how reliable and well-supported their motor and battery system is.

Sizing/Adjustability

Like all Tern electric bikes, the Vektron is highly adjustable to your needs. The Physis handlepost with quick release stem lets you easily adjust the angle and height of your handlebars within a certain range. The easily adjustable telescoping seatpost is also a boon. Overall, the Vektron is a great choice for multiple riders to share between them.

My primary critique of the versatility of the Vektron is about its rider weight limit of 230 pounds. Our other bikes can typically accommodate riders of 250-275 pounds or more. The maximum overall weight that can be added to the bike is 275 pounds for rider and cargo/kid combined. The rack alone has a max cargo capacity of 59 pounds, but of course you can only use that max capacity if you weigh less than 216 pounds. Folding bikes do have additional engineering considerations over a fully rigid frame, of course, but I’d love if this bike could handle a higher rider weight. Please do note: Tern does careful testing of its bikes, so 230 pounds is truly the upper safety limit.

Folding/Transport

In my ideal world, the Vektron would weigh less than it does - 50 pounds is barely doable for me to carry up and down the stairs regularly, especially at the end of a workday when I've been moving bikes around. But given its sturdy construction and excellent features, I can't really complain too much - nevertheless, if they found a way to shave 5 pounds off I wouldn't be sad. If you won’t have to lift your Vektron up and down two flights of stairs every day, then I doubt it will be an issue for you.

It's taken me a while to get used to the folding system. Tern’s videos show a very slick 10-second fold which I cannot pull off even after three months of folding this bike three to four times a week. You may have more success than me though - I have gotten faster even with my lack of coordination.

The bike folds down to a good size for storing next to the stairs at my house, staying out of the way. I put a protective cover down to spare the carpet from dirt, mud, and water stains.

You can also wheel around the Vektron folded, using the seat post and saddle as a handle. When I take my Vektron on the Metro bus, I fold it before the bus arrives, using the bungee cord to hold the front and back sections together, and then lift it onto the bus and wheel it down the aisle! Here’s what I recommend if you take your Vektron on a Metro bus: park it in the front section, using the bungee to strap it to a folded-up seat if there is room. Or if you're on one of the bus models that has some single seats near the front, you can take the single and park it next to you. I’ve also parked it in the middle section of an articulated bus, but I had to hold it upright or it would fall over! On light rail, a folded Vektron fits in the luggage area or in the doorway. Folding the handlebars lets you hang the unfolded Vektron on the bike hook without the handlebars taking up half the aisle!

Battery Life

I get about 35 miles out of one full battery charge, traveling mostly in Eco (the lowest level of electric assist) and sometimes in Tour (the second lowest level), on a mostly flat commute with a few steep hills. I've been impressed with how well the 400wh battery performs. Depending on hills, your electric assist mode preference, and how much weight you carry on your bike, your mileage may literally vary.

Handling

One of the things that initially endeared me to the Vektron is how speedy and nimble it feels compared to larger ebikes. At the same time, it doesn't ride like a folding bike - it’s strong and sturdy! Tern’s expertly engineered hinges on the handlepost and frame contribute to how solid this bike feels.

Cargo, Kids, and Weight Limits

You can attach a single Yepp Maxi or Nexxt Maxi kids seat, but that will interfere with the ability to fold the bike (you can take the child seat off as needed). I use a single Ortlieb pannier on the back, and even on my old style of Ortlieb I can adjust the attachment system to fit. I think it would be even easier with the modern Ortlieb bags.

The kickstand keeps this bike pretty upright, so watch what weight you’re balancing when loading or unloading - it can tip over with too much weight on the right side of the bike.

Maintenance Considerations

This is my first time owning a bike with disc brakes, let alone an electric folding bike with disc brakes! And as a mechanic with two and a half years experience working on Bosch-equipped Tern bikes, I have some wisdom to pass on.

First of all! Do not forget to charge your battery. I am constantly forgetting to do this, partly because my bike storage area is not convenient to any outlets, and partly because I’ve never had a bike that needed to charge before. Then I’m playing bike chicken - riding my bike with the motor off for a mile or two at a time to save my electric assist for the big hills, trying to keep my Range estimate on my bike computer from hitting zero. In conclusion, don’t be like me. It’s not a good idea to completely run out your battery - charge it more regularly in smaller amounts, and you can keep riding happily even if you add a few extra trips to your routine.

Second: Avoid riding through greasy, grimy puddles, which can wreak havoc on your disc brake system. With these small 20” wheels, your disc brake rotor and pads are much closer to the ground than they are on a 26” wheel. A puddle with some oil in it can easily splash up and contaminate your rotor and/or pads. If your bike squeals when you brake, even under dry conditions, you probably have contaminated rotors or pads. We can sometimes correct this by cleaning the rotors and sanding the pads, but in the worst case scenario, replacing both components is required. And that gets pricey! (Don’t forget to lube your chain too - I’ve lubed my chain twice since I got this bike.)

Third: If you hear a creaking sound from your handlebars when you pull on them or put weight on them, you may need to grease under the folding stem. I fold my bike every day and any existing grease quickly gets worn off. Apply a thin layer of thick bike grease (such as the Motorex bike grease we sell, or any other brand) to the flat parts under the folding stem and check if it still creaks.

Fourth: If you hear a weird clicking noise with a pannier installed on the left side, check to see if the pannier is pushing the magnetic latch (used to hold the front wheel against the back when folded) into the hub. You might need to change how you attach your pannier to avoid this issue.

Fifth: book regular maintenance, and do it in advance. Coronavirus has changed everything about how G&O operates, so making advance appointments for regular service will ensure your bike gets the service it needs, when it needs it, and before components wear out completely. In particular, contact the service department to book your free 300-mile/60-day service when you get your bike, especially if you expect to ride more than 25 miles a week in the first three months.

Options

The Vektron comes in two Bosch-equipped models - the Q9 and the S10. The Q9, at $3,199, has the Bosch Active Line motor and Shimano brakes, while the S10, at $3,999, has the Bosch Performance Line motor and Magura brakes. Different colors are available on each model. I went for the Performance Line model in black/bronze because I wanted a motor that can stand up to some of the steep hills I encounter. 

The Active Line model is also a solid choice with reliable Shimano brakes, just less torque in the motor, so it’s less powerful on hills. One of the color choices is a beautiful blue that I definitely would have chosen, if it were available with the Performance Line motor.

Consider This Bike

I hope that I’ve given you lots of food for thought about why the 2021 Tern Vektron S10 is a great bike. It is the only Bosch-equipped folding bike sold by any manufacturer in this country, and it's also sturdy, reliable, and well-built! I’m very glad I chose it and I enjoy riding it.