EUYbike S4 Review, 2024 | Moto Looks; Moto Power

Our Range Test, explained above, is designed primarily to evaluate an e-bikes battery capacity and the efficiency of its motor/battery pairing.

The EUYbike S4 is an unusual case (we seem to have a lot of those, for various reasons) due to a few distinguishing factors. First, with the battery’s capacity. The S4’s webpage advertises a 48V, 25 amp-hour (Ah) or 1,200 watt-hour (Wh) unit, but the one on our test bike was a 20 Ah or 960 Wh power source. We reached out to the company for clarification, and they advised us that the battery capacity has been upgraded. Larger capacity is always appreciated, but we were only able to evaluate the older, smaller capacity unit.

Next, regarding the range estimates advertised by EUYbike; the S4’s webpage states a throttle-only range between 40 and 44 miles, and a pedal-assist result between 49 and 75 miles. These figures were calculated based on the larger 1,2000 Wh battery and the differing speed limitations I mentioned previously, and so are not quite accurate for comparison purposes.

We measured a distance of nearly 28 miles in PAS 5 and around 49 miles in PAS 1, which might not seem fantastic when compared to EUY’s claimed range, but are both very good when compared to similar e-bikes we have tested. The battery on our test bike didn’t have quite enough power in reserve to push the S4 to the top spot among moped-style e-bikes, but we can estimate that the bike would have ended up at – or near – that position with the larger 1200 Wh supply.

We don’t often test e-bikes with battery watt-hour ratings so close to (or exceeding) the 1000 Wh mark. We also don’t often have the opportunity to evaluate 1000W motors, which of course are considerably more voracious than 750W units. There are relationships between these specs that we discuss in our guide to e-bike batteries, but our results indicate that the S4’s motor/battery pairing is efficient.

It’s worth noting that we do not (currently) evaluate range using just throttle power in our Range Test, and so cannot speak to the accuracy of EUYbike’s estimate of 44 miles – but that, too would likely be affected by the smaller battery on our S4.

Regardless of the differences between our results and the range and speed estimates/calculations made by EUY, we are satisfied with the distances we measured. The S4 demonstrated that it has endurance for a moderately lengthy trip in its max-assist setting, and users who want to extend its range can opt to ride the bike in lower (but no less capable) settings.

Here again, the EUYbike S4 presents itself as a unique case study. In our Hill Test, which you can read more about in the graphic above, the bike’s results were mixed.

On throttle power, the bike meandered its way to the summit in 1 minute and 40 seconds, with an average speed of just 10.8 miles per hour. With pedal assistance in PAS 5, it sped uphill in 1 minute and 15 seconds at an average speed of 14.5 mph.

If we compare this to other moped-style e-bikes we’ve tested, the S4 finds itself in the middle of the pack when it comes to max-assist results, and trailing behind somewhat with just its throttle. We found these results to be surprising, considering the bike’s previously established speed, its 1000W motor, and the 96 Newton-meters (Nm) of torque its motor is rated for.

We don’t intend for our Hill Test to be a determining factor for whether a bike is “good” or “bad;” these are terms that are defined personally. Despite the fact that we had higher expectations for the S4 in this test, the fact that it made it up the Hell Hole trail is enough for us.

The S4 uses hydraulic disc brakes on 160mm rotors. We always appreciate hydraulic systems, and generally consider them essential on e-bikes capable of Class 3 speeds, or higher in this case. At least on paper, the 160mm rotors looked a little on the small side to me – but I was happy to be proved wrong.

After three demonstrations, we calculated an average stopping distance of 18’-11”, which is currently the best performance we’ve seen on a moped-style e-bike. It’s also just under our broad current average of 19’ which accounts for all of the e-bikes we’ve tested.

The bike’s additional safety features include its oversized headlight (which also includes a running light), taillight (which includes brake lights), and an electronic horn.

Additionally, the S4 includes an unusually robust settings menu that allows for a massive amount of customization. Most relevant is the ability to limit the bike’s maximum speed, but its throttle (or pedal-assist system) can also be deactivated, or set to only function when the bike is in motion (throttle after pedal). In some locations, limiting the bike’s speed through this menu could be enough to make it road legal.

Assuming that the proper steps are taken – whether that means the bike’s settings are adjusted or it has been registered – we think it would make a fun and highly capable street bike. However, for additional safety and communication with other motorists, we’d love to see turn signals included in the future. This would take the already awesome S4 to the next level!

We have established that the EUYbike S4’s ride is appreciably comfortable, so I won’t go into more detail than I already have on that topic. But we have not yet covered the bike’s handling!

With 20”x4” fat tires, the S4’s handling feels responsive, although its turning radius is impacted slightly by the dual-crown suspension fork. Leaning into corners helps to solve this problem, and the S4’s knobby tires provide more than enough grip and stability to enable this.

I took the bike off-road over compacted dirt and loose sand in my testing, and thoroughly appreciated the bike’s full suspension. While it felt a bit out of place on narrow singletrack, I was impressed by how competently the S4 handled a rough dirt road. Its tires and motor almost lost out in a few inches of sand, but with a leg for added stability, I made it out. All-in-all, I was pleasantly surprised by the bike’s off-road feel!

Of course, we have a few minor areas of critique – or at least some things to be aware of. We appreciate the uncommon level of flexibility and customization offered through the bike’s settings menu (including the ability to limit speed or deactivate the throttle), but its 1000W motor greatly reduces the S4’s likelihood of being road-legal without a license and registration. Additionally, for increased safety and ease of communication with other drivers, we’d love to see turn signals that allow the rider to keep both hands on the handlebars.

Thrill-seekers looking for adrenaline will get their fix thanks to the bike’s huge and hungry motor and unrestricted speeds. Those looking for a casual ride over a long distance will appreciate the S4’s plush saddle, user-friendly cockpit, and impressive battery capacity. And savvy riders who want to get a seriously powerful and cool-looking bike without breaking the bank will certainly love the EUYbike S4’s price point.

In short, we found a lot to enjoy through our experiences on this bike, and we think you will too!

Happy Riding! Make sure to let us know if you have any questions down in our comments section or if you think we left anything out in this review of the EUYBike S4.