Tern Vektron P5i Review | Premium, Purpose-Driven & Portable

Since an e-bike’s range is typically one of the most important factors in most buying decisions, we test every model to see how far it can travel on a single charge. Using the method explained above, our test riders covered 25.9 and 71.4 miles on the Vektron P5i, which lines up well with Tern’s advertised 28-70 miles of range.

A group of similar e-bikes we tested previously, including many of the best folding electric bikes, averaged 23.8 and 52.6 miles in their high-power and minimum-assist tests. With these results in mind, the Vektron was roughly average in its Turbo mode test and significantly above average in Eco.

The main difference between the Vektron P5i and our group of comparison models is its mid-drive motor. We simply haven’t encountered many mid-drive-equipped folding e-bikes, as this type of motor is typically more expensive than a hub-mounted motor, and also adds complexity to the design and engineering of folding frames.

Mid-drives are also commonly more efficient than their hub-mounted counterparts, which is apparent in the data when breaking down the amount of energy used per mile by each e-bike.

The bikes used for comparison had slightly larger batteries on average (418 Wh) and used an average of 6.9 and 17.1 watt-hours per mile (Wh/mi) in their minimum and maximum assist tests, respectively. With its 400 Wh battery, the Vektron averaged just 5.6 and 6.9 Wh/mi in its Range Test, stretching its charge over a greater distance.

A potential real-world range of 26-71 miles means that most riders should be able to cover multiple round trips on a single charge. It also makes the Vektron P5i suitable for multiple uses, including exercise rides, commutes, leisure trips, errand running, family outings, and beyond.

Conveniently, the bike includes a 4A fast charger that can fully recharge a drained battery in under 3 hours. This means that riders should be able to get pedaling again quickly when either they or the bike need a break.

In our Hill Test at the Devil’s Backbone (see the graphic above for a description of this test), the Tern Vektron P5i finished in 2:29. As our test rider, Justin, traveled up the hill during his single pedal test, he maintained an average speed of 12.3 mph.

Comparing the Vektron’s results to those of similar models is difficult. When considering its performance in relation to that of folding e-bikes, we again have only models with rear-hub motors to compare against. Other mid-drive-equipped e-bikes, however, differ greatly in style and power.

While we’re not able to compare apples to apples in either case, considering the performance of both of these groups can give us a valuable perspective on the Vektron. For a better picture of the Tern’s performance, the bike weighs roughly 54 lbs and its motor produces up to 600W and 65 Nm of torque.

Mid-drive-equipped e-bikes we’ve tested at the Devil’s Backbone (not including high-powered eMTBs) averaged 2:22 when using their highest assist levels—just 7 seconds faster than the Vektron, which is within our margin of error. These bikes weighed more (66 lbs) and had more powerful motors (757W and 95Nm), making the Vektron’s results impressive for its specs.

Other folding e-bikes finished their pedal tests in an identical average time of 2:29. These bikes averaged slightly higher weights of around 61 lbs, similar torque ratings (67 Nm), but motors with significantly higher peak output (1097W).

With the results of these different but relevant groups in mind, the Vektron P5i proved highly capable of helping its rider pedal over steep hills. In my personal testing, the bike’s natural feel means that you’ll get a light to moderate workout when pedaling uphill, so the experience will likely increase your heart rate and make you breathe harder, but it won’t be exhausting.

This is the beauty of an e-bike; the job of climbing an intimidating hill can be made possible, relatively easy, and even enjoyable as long as you’re willing to put in a relatively small amount of legwork.

After testing the Tern Vektron’s braking performance using the method above, its average stopping distance was 22’1”. This distance is admirable, falling well within our expected range of safe, effective results. It is, however, somewhat longer than average when compared with similar models—a group of other popular folding bikes scored just 19’3”.

In recent months, the folding e-bike category has made some waves in our database; a few models posted uncommonly short average stopping distances that skewed our data somewhat. With those e-bikes removed from our comparison group, the average jumped to 20’6”, narrowing the gap with the Vektron P5i while still showing it as slower than average.

Based on our collective experience and my personal testing, I believe there are two likely contributing factors to the difference in results.

First, while the Vektron P5i has a high-quality Magura MT4 hydraulic brake system, which is known for solid, balanced performance, it is paired with relatively small 160mm rotors on both wheels. Larger rotors improve heat dissipation, which correlates to stronger, faster braking.

Second, the Vektron’s Schwalbe Big Apple tires improve the bike’s overall ride comfort, but they are made of a fairly firm compound. Softer, gummier tires tend to provide better grip, which helps to shorten stopping distances.

In my personal experience on the bike, its brake system felt strong, but it did have a tendency to skid more than I initially expected. The brakes modulated speed well when riding downhill, they brought me safely to a stop each and every time, and they felt safe at all times.

Those who want to improve their braking might consider changing the Vektron’s tires or upgrading its rotor size. Considering its feel and that the bike’s test score fell well within the safe zone, however, I do not believe that Tern needs to make any changes. For personal safety, I might recommend that new riders practice their braking to understand the bike’s behavior.

The subject of ride quality can be a complex topic when discussing premium, Bosch-equipped e-bikes, but I found the Vektron P5i refreshingly straightforward and simple. Bells, whistles, and tons of features can make a bike stand out, but simplicity is also a beautiful thing; the Vektron is a great example of the latter.

Tern makes the P5i in a single frame size. With 11.75 inches of saddle height adjustment, courtesy of a dual-telescoping seatpost, and the brand’s custom adjustable Andros stem, it can realistically accommodate riders from roughly 4’10” to 6’5”.

Those on the taller end of the spectrum may have a more forward-leaning riding position, while shorter folks may be more upright, but in all cases, they should be reasonably comfortable.

At 5’11”, I fall well within the bike’s advertised height range, and I enjoyed a comfortable, properly-fitted ride with full leg extension and mostly upright positioning. I also liked the bike’s sport-style saddle and soft, supportive ergonomic rubber grips.

As I mentioned in the introduction to this review, the Vektron P5i’s handling was also a highlight. At 54 lbs, it may not exactly be lightweight, but it is far more nimble and maneuverable than many other folding e-bikes we’ve tested weighing upwards of 70 lbs. The bike steered quickly, cornered predictably, and generally felt lively and agile.

While the bike does not feature any form of suspension, its 20×2.15” tires offer enough width and volume to smooth and stabilize the ride. While I typically stood to avoid jarring impacts when rolling over large bumps, the combination kept me comfortable in general riding situations.

I’ve discussed the motor’s responsiveness, but it’s worth reiterating that the bike is remarkably natural-feeling and intuitive. As we’ve commonly found when reviewing Bosch-equipped e-bikes, the Vektron’s pedal assist system is top notch, with mostly quiet operation, smooth power delivery, and enough power to supplement your pedaling without overtaking it.

I found the P5i to be approachable and uncomplicated with a low learning curve. The bike’s interface is straightforward, with a handlebar-mounted button pad to adjust power level, a basic-but-effective black-and-white display with a wide array of ride data, a high-powered integrated lighting system, and a twist shifter for the 5-speed Shimano Nexus hub.

Experienced riders should have no trouble hopping on the bike and pedaling, while those new to e-bikes should only need a brief run-through of its functions to be ready to roll.

In addition to the basics, the Vektron P5i comes with a well-placed removable battery, an ABUS rear wheel lock, fenders, a chain guard, and a cargo rack that can carry up to 59 lbs. Riders looking to equip the bike for more utility can add optional storage baskets and bags, along with a front rack or luggage carrier.

I found the bike generally well-equipped for daily use, though I had hoped to see integrated brake lights and perhaps turn signals—especially considering its urban-centered design.

I was also somewhat disappointed to learn that the Bosch Flow app, which allows users to tune motor output, access security features, and get navigation, is only available on Vektron models outside the US. Our contact advised us that Tern opted for a lower-tech option to reduce cost, but I wouldn’t mind seeing an upgrade option in the future. After having the chance to test the app previously, I missed these features on the top-tier model!

As a folding e-bike, the Vektron’s portability factor is another important element of its engineering and construction; Tern advertises a 10-second folding time to get the bike ready for storage, packing into a vehicle, or rolling on public transit.

While I didn’t quite get the process down to such a short time, it is clear to me that it is possible with more practice. The folding process is simple; users have only to drop the saddle, adjust the handlebar angle, open the hinged frame, then rotate the front wheel so its metal plate will contact the rear wheel’s magnet. With the collapsible stem folded and both wheels secured, a rubber strap can hook to the stem for extra security.

Additionally, once folded, the drive-side pedal can be removed via a quick-release mechanism to reduce the bike’s overall width. It’s an elegant design that is fast, works well, and feels generally intuitive. Once collapsed and folded, the bike measures roughly 33.5”L x 16”W x 27.5”H.

Tern’s e-bikes are also known for a unique party trick: many models offer the ability to stand vertically on four “legs” that protrude from their cargo rack. The Vektron is one such model; the bike can stand upright when folded or unfolded for stability and to take up less floor space.

In summary, the Vektron P5i is just about everything we’d want in a premium folding e-bike; it’s sturdy, agile, comfortable, responsive, and both extremely utilitarian and easy to use. The fact that its sealed, protected drivetrain is clean, quiet, and low-maintenance is simply the icing on the proverbial cake!

E-bikes span the full gamut of price points, from cheap and low-quality to affordable yet functional to premium and optimized for reliability and performance. With a price point over $4k, the Vektron P5i is decidedly on the costlier end of the spectrum, but its quality construction, smart component package, and thoughtful design justify its expense.

We found much to appreciate about the top-tier Vektron. Its adjustability made it comfortable and accommodating and its motor gave it an intuitive and natural feel, while its simple user interface made it easy to learn and operate. Additionally, its modest weight and fast-folding design gave the bike an uncommon level of practicality.

In our testing, the bike performed well across the board, with a great balance of power through its four assist levels, impressive range and climbing performance for its specs, and a solid braking score.

Our only areas of criticism centered around its absence of urban-friendly brake lights and Bosch Flow app connectivity, though the bike generally makes up for these things in other areas.

Overall, the Vektron P5i is a smart, practical, and portable choice for riders seeking a well-outfitted and reliable daily-use e-bike. Whether used as part (or all) of a daily commute, a secondary mode of transit for RVers, a natural-feeling exercise bike, or a full-time errand-runner, we’re confident that the bike delivers excellent value and reliable performance for its premium price point.

Happy Riding! Make sure to let us know if you have any questions or if you think we left anything out in this review of the Tern Vektron P5i down in our comments section.