Super73 Top Speed: Complete Guide to How Fast Each Model Can Go
Super73 top speeds range from 20 mph on the entry-level Z-series to 28+ mph on the R and RX Adventure models when unlocked. Every bike is limited by its electronic controller and battery voltage, but rider weight, tire pressure, and terrain all affect the actual number you’ll see on the display. Here’s exactly what each model delivers.
These figures apply to current production models (2021 onward). Earlier models like the original S1 have different controllers and cannot be unlocked, and some very early run Z1 units lack the app‑compatible controller entirely.
Quick answer
| Model | Top Speed (mph) | Class | Notes |
|---|---|---|---|
| Z1 | 20 | Class 2 | Twist‑throttle only, fixed at 20 mph; no unlock possible |
| ZX | 20 (unlocked to 28 via app) | Class 2 / unlockable to Class 3 | Requires Super73 app to remove the 20 mph limiter |
| S1 | 20 | Class 2 | Older model, permanently capped at 20 mph |
| S2 | 20 (unlocked to 28 via app) | Class 2 / unlockable to Class 3 | Same motor and battery as RX; hardtail frame |
| RX | 28+ (unlocked) | Class 3 | Factory-set at 28 mph, no further unlock available |
| R Adventure | 28+ (unlocked) | Class 3 | Heavier tires reduce real‑world top speed by 1–2 mph vs RX |
Key takeaway: All current Super73 models leave the factory capped at 20 mph for legal Class 2 compliance. The ZX, S2, RX, and R can be unlocked to 28 mph through the official app, turning them into Class 3 e‑bikes. The Z1 and S1 are locked at 20 mph permanently.
Practical implication for buyers: If you’re choosing between models, the real question isn’t just top speed—it’s whether 28 mph is worth the extra cost, weight, and legal hassle. For most commuters, 20 mph is plenty and maximizes range. If 28 mph matters, skip the Z1 and S1 entirely; only the ZX, S2, RX, or R can reach it.
Verification step: To confirm your bike’s actual top speed, ride on flat ground with a full battery, set assist to the highest level, and hold full throttle for 30 seconds. Check the display. If it shows 20 mph and you expected 28, open the Super73 app, go to vehicle settings, and verify the Class 3 unlock is active. If the unlock button is greyed out, you may need to accept the rider agreement or update firmware first.
Comparison framework
Top speed on a Super73 isn’t just a number on the spec sheet. Three factors decide how fast you can actually go:
- Motor output: The S2, RX, and R use a 750W nominal hub motor (peaking around 1200W). The Z-series uses a 500W nominal motor. More power lets the bike hold speed uphill and against wind.
- Battery voltage: The 48V battery on the S2/RX/R supplies more voltage to the motor than the 36V pack on the Z1/S1. Higher voltage means higher RPM at the wheel, so the bike can reach higher gearing-limited speeds.
- Class limiter: The controller firmware enforces a speed ceiling. Unlocking via the app removes the 20 mph cap, but the physical motor and gear ratio still set the true maximum—typically 28 mph for the larger motors.
Applicability boundary: The unlocking feature requires a controller that supports the app. In 2020, Super73 shipped some ZX units with a Gen 1 controller that could not be upgraded. If you buy a used ZX, check the controller part number (look for a sticker on the underside of the battery tray). Gen 2 controllers have a visible QR code and support app unlock. Gen 1 units are permanently limited to 20 mph.
Trim exceptions: The ZX shares the same frame and motor as the Z1 but uses the newer controller that supports app‑based unlocking. If you buy a ZX thinking you’ll get 28 mph out of the box, you won’t—you have to install the Super73 app and agree to the Class 3 rider agreement. The same applies to the S2: the unlock is not permanent; it resets if the battery is disconnected for a long period, and you must re‑authenticate occasionally through the app.
Real‑world reality: Even unlocked, expect 25–27 mph on a warm day with a 180‑lb rider, not a solid 28. Cold weather (below 50°F) saps battery voltage, and you’ll likely see 24–26 mph until the battery warms up after 5–10 minutes of riding.
Best‑fit picks by use case
For pure speed (28 mph, no compromises)
Get the RX or R Adventure. Both come with the 750W motor and full suspension (RX has front fork, R has front + rear). They unlock to 28 mph via the app and hold that speed on flat ground with a 180‑lb rider. The RX is lighter and more nimble; the R is built for rough pavement and light trails. Note the R’s fat 5-inch tires add rolling resistance that shaves about 1 mph off the top end compared to the RX.
For budget + unlockable speed
Get the S2. It costs less than the RX/R, shares the same 750W motor and battery, and unlocks to 28 mph. You lose suspension (hard tail) and get smaller tires, but the top speed is identical. Expect about 25–27 mph real‑world depending on tire pressure. The S2 is also lighter than the RX by about 10 pounds, making it easier to carry.
For short commutes where 20 mph is enough
Get the Z1 or ZX (if you don’t plan to unlock). The Z1 is the lightest and cheapest, but has no suspension and a smaller battery. The ZX is a better ride with a slight suspension fork and a larger battery, but it’s still capped at 20 mph unless you unlock it. At 20 mph you’ll get the longest range per charge. One reservation: the ZX’s unlock is worth doing for extra safety on roads with faster traffic, even if you rarely use full speed.
For legal peace of mind (no unlock needed)
Get the Z1 or S1 (used market). These are permanently Class 2, so you never have to worry about local enforcement of Class 3 limits. Speed is 20 mph, and the range is good because the motor isn’t working as hard. However, the Z1’s 500W motor struggles on hills above 8% grade, so if your commute has steep climbs, you’ll want the 750W motor in the S2 or RX—even at 20 mph.
Trade‑offs to know
Speed vs. range: Every mph above 20 costs you range. At 28 mph the motor draws significantly more power, and real‑world range drops by about 30–40% compared to riding at 20 mph. On the R Adventure, a full charge might get you 25 miles at 28 mph versus 40 miles at 20 mph. If you need to cover 30+ miles daily, stay locked at 20 mph.
Weight penalty: The RX and R weigh 65–75 lbs. The heavier frame and fat tires make them slower to accelerate and harder to pedal without power. The Z1 at only 40 lbs is much easier to carry upstairs or onto a bus. The S2 sits in the middle at 55 lbs—still heavy but manageable.
Legal risk: Unlocking to 28 mph makes the bike a Class 3 e‑bike, which may require a license, registration, or minimum age in some states. Super73’s app requires you to agree to local laws before unlocking, but the responsibility is yours. If you get pulled over, the bike’s display still shows 28 mph. Some local parks and trail systems prohibit Class 3 bikes entirely. Check your local regulations before unlocking.
Wheel size and tires: The S2 and ZX run 20” x 4” tires that are shorter in diameter, which lowers the effective top speed slightly (by about 1–2 mph) compared to the 20” x 5” fatties on the R Adventure. Bigger tires have more rolling resistance, so the RX with 20” x 4.5” tires gets the highest real‑world speed on the 750W motor. The trade‑off: the R Adventure’s fat tires give better stability on sand and gravel, but you lose 1–2 mph on pavement.
Cold weather limitation: Below 50°F, lithium-ion batteries produce lower voltage, and the motor can’t sustain its peak RPM. Expect 2–4 mph less on any unlocked model until the battery warms up after extended riding. This is not a defect—it’s a characteristic of all e‑bike batteries.
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Ryan Williams has spent over 8 years testing, repairing, and writing about electric bikes. He has personally ridden and reviewed 150+ e-bike models from brands like Lectric, Aventon, Rad Power, Super73, and dozens more.
Before founding EBIKE Delight, Ryan worked as a bicycle mechanic for 5 years at independent bike shops across California, where he specialized in e-bike conversions and electrical system diagnostics. He holds a Certificate in Electric Vehicle Technology from the Light Electric Vehicle Association (LEVA).
Ryan’s work has been cited by Electric Bike Report, Electrek, and BikeRumor. When he is not testing the latest e-bike on California backroads, he is in his workshop tearing down batteries and controllers to understand what makes them tick — and what makes them fail.
Areas of Expertise
E-bike performance testing and real-world range verificationBattery diagnostics, charging best practices, and safetyBrand comparisons: Lectric, Aventon, Rad Power, Super73, and moreError code troubleshooting across major e-bike systemsE-bike laws, registration, and compliance by state
Ryan believes every rider deserves honest, hands-on information — not marketing hype.