Electric Bike Reviews, News, & Testing
Electric Bike Report
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With its two Go5 e-bike models, PHOSGO asks a question that few other e-bike brands have attempted to tackle: what if your e-bike had a built-in solution to recharge the battery as you go?
It seems like a no-brainer.
After all, riders are outside, often enjoying daylight and fresh air, so why not give them the ability to harness the power of the sun to extend their rides? To accomplish this goal, PHOSO has developed the unique solution of building four 50W solar panels directly into the wheels of its e-bikes.
When pedaling, these panels send power to the motor, theoretically reducing its draw on the battery. When coasting or parked in direct sunlight, the collected solar energy is sent to the bike’s power pack. PHOSGO’s marketing claims that the solar panels can recharge the battery by up to 17% per day, offering some riders “up to 30 days between plug-in charges.”
These are bold statements that, if successful, could change the way e-bikes are made and used. At the time of writing, PHOSGO is set to complete a successful crowdfunding campaign through IndieGogo, having raised nearly $400,000 through over 160 independent backers. Supporters have two models to choose from: the Go5 Pro and Go5 Ultra.
We tested a prototype version of the bike that most closely resembles the Go5 Pro in specs and components, but both production models offer some significant differences from our test bike. For example, our test bike came equipped with a 500W Ananda mid-drive motor and a 499 Wh battery with Lishen cells. It also had a 7-speed drivetrain with a Shimano Tourney derailleur and Gemma hydraulic disc brakes with 180mm front / 160mm rear rotors.
In contrast, production Go5 Pro and Go5 Ultra models have either a 500W or 750W Bafang mid-drive paired with a 480 Wh or 720 Wh battery, respectively. These batteries are made with LG cells. They also feature 8-speed Shimano drivetrains, knobby SUV-style tires, and hydraulic brake systems with dual 180mm rotors.
These spec differences led us to approach this review somewhat differently than normal. As always, we ran our test bike through our standardized testing process, but given some expected differences in performance, our main goal was to focus on the concept and performance of the integrated solar panels.
See below to find out how the Go5 Prototype performed, how we expect the production models to differ, and if the bike’s solar technology is truly as promising as it sounds!



There’s no missing the Go5’s wheel-mounted solar panels!
Each solar panel is rated for 50W, creating a combined total of 200W of power.
Production models will come with Bafang motors, but our test bike was equipped with a 500W Ananda mid-drive.
The PHOSGO Go5 Prototype had a great start in our testing with our Speed Test. As a Class 1 and 2 e-bike, it offers throttle and pedal assist up to 20 mph. We tested the average speed of each assist level by riding on a mostly flat, paved path, then tested its throttle acceleration from a stop up to maximum speed.
I began the test by riding without pedal assist. Under leg power alone, the bike’s roughly 70-lb weight was somewhat noticeable, though its weight distribution and the low rolling resistance of its street tires helped to make pedaling comfortable and relatively relaxed.
As shown by the graph of my average speeds above, even the bike’s lowest assist level delivered an impactful and entirely usable level of power. Each next-highest power level allowed me to ride faster, providing measured increases in speed.
The feel of our test bike’s Ananda mid-drive was a highlight, delivering power in a way that felt both natural and rewarding. Pedaling the Go5 Prototype generally felt intuitive—like riding an analog bike that was both faster and less strenuous.
One element of the bike’s programming may be somewhat divisive: upon reaching 13, 15, 17, 19, and 21 mph in PAS 1-5, respectively, the bike’s motor will shut off, effectively limiting riders to these speeds.
On the plus side, this allows riders to easily control their speed and/or limit power consumption to manage the bike’s range. Some riders who would otherwise find lower power levels usable by feel, however, may skip them simply to be able to reach the bike’s maximum speed.
Let’s consider some similarities and differences between the production Go5 models and our prototype test bike.
The Go5 Pro shares our test bike’s 20 mph maximum speed and a 500W mid-drive motor, though its drive unit is made by Bafang rather than Ananda. Given our test bike’s rewarding feel, I expect the Pro’s Bafang motor to perform similarly. Our 7-speed test bike felt somewhat loose near its highest speeds, however, so I was happy to note that the Pro has an 8-speed drivetrain to better allow riders to keep up with the bike’s speed when pedaling.
The Go5 Ultra, on the other hand, has a 750W Bafang mid-drive with significantly more power and torque. As such, while I expect a similar feel in the bike’s lowest assist levels, I anticipate a less-natural feel in the highest settings due to the motor’s additional muscle. It can also reach 28 mph via pedal assist, which I expect its 8-speed drivetrain to also accommodate well.
As for the throttle, I liked the comfort of our test bike’s half-twist throttle, which was mounted to the right handlebar. As is common with throttle-equipped mid-drives, acceleration wasn’t remarkably quick (accelerating to top speed requires stepping up through the gears, just like pedaling), but it was controlled, functional, and welcome nonetheless.
Overall, the Go5 Prototype showed well-balanced programming, natural, intuitive power delivery, and the ability to reach its advertised maximum speed, all of which made a solid first impression.
PHOSGO designed the Go5 to be a capable daily commuter or off-grid adventure bike.
Our test bike used a 7-speed Shimano Tourney drivetrain, but production models get an upgrade to an 8-speed Altus.
The Go5 Prototype’s mid-drive was paired with a fully-integrated but removable 499 Wh battery.
Given PHOSGO’s marketing, our Range Test was perhaps the most interesting of our standardized performance tests.
We rode the bike on a network of paved shared-use paths, starting with a full charge and riding until the battery was depleted. In typical fashion, we performed separate tests using the highest and lowest pedal assist levels, though the Go5 Prototype’s solar panels added an extra dimension to our process.
We ran two max-power tests—one with the solar panels connected to the bike’s system and the other with them disconnected—to see what effect they had on the bike’s range.
In our PAS 1 test, we were pleased to note that the Go5 Prototype met PHOSGO’s advertised claim of 62 miles. In PAS 5, the bike traveled 23.8 miles with solar panels connected.
Before addressing the impact of the solar panels, let’s pause to consider this baseline performance in relation to similar e-bikes we’ve tested. Similar commuter-style e-bikes we’ve reviewed averaged 37.1 and 74.0 miles on batteries averaging 715 Wh, so while the Go5 Prototype had lower range results, this is understandable given its smaller-than-average 499 Wh battery.
In terms of energy consumption, the prototype straddled the averages among similar models; our group of comparison e-bikes used 10 watt-hours per mile (Wh/mi) in their low-assist tests and 19.5 Wh/mi in their max-power tests, while the Go5 used 8 Wh/mi and 21 Wh/mi, respectively.
Ultimately, while its high-power result is on the low end of the spectrum, we can say that most riders should expect to get at least one full round-trip commute before needing to recharge. Others may be able to extend that to multiple trips, depending on where and how they ride.
Again, with its 499 Wh battery and 500W motor, our test bike is most similar in specs to the production Go5 Pro model, which has a 500W mid-drive and a 480 Wh battery. The Go5 Ultra has a 750W motor and a 720 Wh battery, which we would expect to provide similar range given the more powerful motor, though whether these bikes share our test bike’s speed limits is just one factor that will influence their range.
Now, to continue with our explanation of test results, the Go5 covered 27.3 miles with its solar panels unplugged. This means that, while we had different riders perform our two max-PAS tests, the bike actually performed better with its solar panels disconnected. Case in point: its energy consumption dropped from 21 Wh/mi to 18.3 Wh/mi.
As you might understand, this result was unexpected, but there may be a good reason for it.
We noticed that, when the bike’s battery was below 20%, its power delivery became very inconsistent. At first, the motor shut off, but after pedaling for a short time without power, it would temporarily turn on again. We decided to stop the test earlier than expected, since the pedal assist system was essentially not helpful at this point.
Upon reaching out to our contact at PHOSGO, we were advised that the bike’s battery management system (BMS) was likely to blame. As a protective feature on our prototype e-bike, the BMS was set to reduce the battery’s output voltage upon reaching 20%; this explains the motor cutoff. After settling, the voltage likely raised above the protective threshold, turning the motor back on again until the voltage dropped again.
Our contact also advised us that the company’s development team was aware of this issue and that a fix would be implemented on production models. While we hope this to be true, we can only report on our findings.
To supplement this range testing, we tested the solar panels’ functionality in two different ways: while riding and while parked. While riding, we found that the solar panels only send energy to the battery after at least 5 seconds of coasting and if the wheels get relatively direct sunlight.
When parked, the solar panels did work to recharge the battery, though at a relatively slow rate; we accumulated roughly 3% of the battery’s charge per hour. A rider leaving their bike parked in the sun for an 8-hour work day could expect to recover roughly 24%, while a full charge would require roughly 33 hours of direct sunlight.
One factor to note is that the bike must be left on while charging. As such, it may need to be secured by a good lock (or multiple security mechanisms) to prevent theft.
Ultimately, our test bike demonstrated usable range for leisure rides and daily commutes, so it should accommodate most riders’ needs. Its solar panels, however, will best work for those traveling relatively short distances who can leave their bike in the sun for comparatively long periods of time.
When compared to similar mid-drive-equipped commuter e-bikes, the PHOSGO Go5 Prototype performed well in our Hill Test. We tested its climbing power using exclusively its throttle in one trip up our test hill (see the graphic above), then its highest level of pedal assist in a second run.
On throttle, the Go5 Prototype reached the top in a relatively average 2:18 at a 13.1 mph average speed. For context, similar models we’ve tested averaged 2:20. It proved significantly faster than average in the pedal portion of the test, however, climbing in 2:04 at 14.6 mph while similar bikes averaged a longer 2:15 result.
The result can be explained by the Go5’s raw power; while it weighs roughly 8 lbs more than the average of 62 lbs, its motor is powerful enough to overcome this limitation and surpass much of the competition. Our test bike’s 500W Ananda mid-drive produces up to 900W of peak power and 120 Nm of torque, while other models in our comparison group averaged a peak of 740W with 91 Nm of torque.
Based on their specs, we would expect the Go5 Pro and Ultra production models to perform even better. The Pro model features a similar 500W mid-drive with a higher torque rating—up to 140 Nm—while the Ultra is even more powerful. It features a 750W mid-drive that can produce a whopping 150 Nm of torque, which should make short work of even the most intimidating hills.
Both the prototype and production models have impressive power, but we found one aspect of our test bike that warrants a word of caution. Since the bike’s solar panels occupy the full interior of the wheels, they can easily catch wind, which can cause the bike to pull to the side when riding downhill. We advise traveling at moderate speeds and keeping a firm grip on the handlebars for safe steering.
The Go5’s solar panels can replenish energy when coasting or when the bike is parked in the sun.
A half-twist throttle sits on the right handlebar.
Our test bike featured Gemma brakes, but production models will use a Shimano setup.
Our Brake Test was a clear area where the Go5 Prototype struggled, though it is worth noting up front that PHOSGO has updated the production models with better brake systems.
We tested the bike by riding up to 20 mph, applying the brakes upon crossing a set of traffic cones, then measuring the distance we traveled before stopping. Our test rider, Michael, performed three tests, which we averaged for a final score.
The Go5 Prototype’s average stopping distance was 27’9″, while a group of similar commuter-style e-bikes we’ve tested averaged 21’5″. This puts our PHOSGO test bike over 6′ beyond average and into territory that typically leads us to recommend changes.
Fortunately, the brand seems to have arrived at the same conclusion. Our test bike came equipped with 2-piston Gemma hydraulic brakes using a 180mm front rotor and a 160mm rear rotor, but production models are set to include 180mm rotors on both wheels. We’re unsure if the brand/model of brakes will change.
In my experience, the brake setup on our test bike felt underpowered for the bike’s size, weight, and speed. The brakes managed to modulate speed decently when riding downhill, but lacked overall bite and muscle; stopping required the application of moderate to high grip strength and still felt delayed.
It’s tough to speculate without testing a production model, but given the Go5 Prototype’s feel, performance, and wheel size, the upgrade from a 160mm rear rotor to a 180mm rear rotor may not be enough.
29″ wheels require large rotors to achieve the same braking force as smaller-diameter wheels, so PHOSGO may need to implement a 203mm F / 180mm R setup (or dual 203mm rotors) to significantly and effectively increase the Go5’s braking performance.
We measured our test bike’s handlebars at around 680mm.
A Suntour XCM suspension fork gave us 100mm of travel, but production models get 110mm.
We found the bike’s saddle soft and supportive.
Sealed holes in the solar panels allow access to the tire valves.
This section is where we do our best to describe the hands-on feel of a bike—essentially how it feels to ride and use. The Go5 Prototype’s solar panels added a few additional facets to its user experience that haven’t applied to other e-bikes we’ve tested, but at the end of the day, it is still a bike, and therefore relatively straightforward to describe.
Beginning with sizing, PHOSGO offers a single frame size in both a high-step and step-thru frame style. The step-thru model is advertised to be best-suited for those between 5’6″ and 6’3″, while the high-step is intended for those from 5’7″ to 6’4″.
At 5’11”, the Go5 Prototype felt generally accommodating for my size. The bike offered adjustability in its saddle height and position via the seatpost and saddle rails, with enough room for proper leg extension (over 8″ of total height adjustment). The riding position was mostly upright with a slight forward lean.
Relatively close but low handlebars meant that I was putting some weight on my palms with my elbows nearly locked. Overall, while I can’t describe the feel as matching my personal preferences, the bike should accommodate most riders. Major changes to handlebar height or reach, however, will require owners to swap out parts to alter the fit.
In terms of handling, the Go5 Prototype performed well. While not a lightweight e-bike, it felt relatively nimble, and I appreciated that its 680mm handlebars offered solid steering control. I noticed some frame flex on our high-step test bike, though it generally cornered and rode predictably.
One area with noticeable room for improvement is the bike’s handling in windy conditions. As mentioned in the Hill Test section above, the solar panels tend to act like sails or kites; I found myself sometimes countersteering to offset the wind’s push. In my experience, this effect never felt egregious, but some form of pass-through in the panels’ design to eliminate wind resistance would be welcome.
Additionally, we found the solar panels somewhat noisy. Instead of being connected to the bike’s wheels, the panels are attached to each other, essentially sandwiching the wheels. At least on our test bike, the edges of the panel were flexible enough to rattle when rolling over some bumps. Our contact at PHOSGO advised us that our bike didn’t have weatherproofing, so this may be less noticeable on production models.
Fortunately, the solar panels seem to be durable; this was one of our biggest concerns going into this review. Traditional solar panels are made with tempered glass, so we were pleased to note that PHOSGO developed lighter-weight solar panels with an ETFE (durable fluorine-based plastic) outer layer to protect against wear.
The solution seems to have worked—while the panels picked up some dirt along the way, we noticed no scratches or other marks from use.
Our test bike included only front suspension, while the Go5 Pro and Ultra models include both suspension forks (with 10mm of additional travel) and suspension seatposts. I found our test bike pleasant to ride—bumps were somewhat noticeable, but effectively softened by the fork, saddle, and tires.
As for the user interface, our prototype test bike included a central color display and a three-button control pad on the left handlebar. This setup worked well, though buyers should be aware that both final versions use a smaller handlebar-mounted display that may be tougher to read.
Production models should also work with the PHOSGO app. I was able to download, install, and pair the app with our test bike, but many of its features did not work (I assume this is due to differences in the prototype’s motor and interface). The app appears to offer OTA updates and location tracking via 4G connectivity, along with navigation, geofencing, etc., though we were not able to test these functions.
Ultimately, the Go5 Prototype’s ride quality was somewhat of a mixed bag. It generally functioned well and rode comfortably, though there is also some noticeable room for improvement in a few areas—which we hope the production models address.
Our prototype used a large central color display, while production models use a smaller handlebar-mounted unit.
We appreciated the simple control pad, but would likely upgrade to lock-on grips.
Our bike was limited to an integrated LED taillight, but consumers can expect a taillight as well.
The 29″ Kenda street tires offer low rolling resistance and good grip on pavement.
From our perspective, innovation and creativity are things to celebrate. After all, technology can only progress when individuals have the boldness to dream up an idea, the determination to overcome setbacks and engineering challenges along the way, and the drive to see their concept fully realized. This is the pattern that paves the way for the next generation.
E-bikes wouldn’t be here without such resolve; the first patent for a rear-hub electric bicycle in the US was given to Ogden Bolton Jr. as far back as 1895. It took nearly another hundred years for the concept to be mass-produced by the Japanese music, audio, and motor company Yamaha, and another thirty-plus years to bring us to the present.
From this perspective, PHOSGO is doing necessary work with its Go5 e-bikes. The company is pursuing the vision of a future where riders rarely, if ever, need to plug in. Based on our experience with the Go5 Prototype, there is some merit to the idea of an e-bike carrying solar panels to turn the sun’s energy into battery power. It is also clear that the idea needs continued development.
Based on our experience with the Go5 Prototype, we’re pleased to see that PHOSGO gave the production models some welcome improvements. We liked our test bike’s Ananda mid-drive motor, but the Bafang models on the Go5 Pro and Ultra should perform similarly well. We expect the upgrades in brakes and drivetrains (with electronic shifting on the top-tier model) to improve ride quality and performance, as well.
Hill climbing was a particular strength of our test bike; the powerful mid-drive made short work of steep hills, providing ample power to reduce strain and speed up the process of tackling hills.
As far as the Go5’s solar technology is concerned, this aspect of the bike is somewhat of a mixed bag. Considering that our Range Test riders traveled further without the solar panels than with them (on a continuous ride), we anticipate that PHOSGO will continue to refine its concept to improve its practicality.
We give the company credit for the progress it has made thus far—the conductive wheel hub that makes the technology work is particularly impressive—but we also encourage it to continue development and reduce wind resistance in its wheel design.
So what’s the bottom line? For riders with relatively short commutes who can leave their bike in the sun to recover energy, the Go5’s solar technology could prove useful. Those who cover long distances regularly will likely still need to rely on the standard charger, given that the solar panels only provide a relatively small trickle of energy that takes a while to add up.

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 PHOSGO Go5 Prototype down in our comments section.
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