Jasion Thunder Pro Review

Jasion claims 0 to 20 mph in 5 seconds. We measured 8.0 seconds, on throttle alone and on maximum pedal assist, across multiple runs with a full battery. The claim doesn't hold, but the result is still strong: 8 seconds ties the Himiway Cobra and Mokwheel Obsidian for the fastest throttle run in this comparison group. Power builds smoothly rather than abruptly.

The Thunder Pro ST really shined in our climbing tests. It finished the gradual hill (0.99 miles at up to a 6% grade) in 2:03 at an average of 29.0 mph: the fastest time in the comparison group, edging out the Heybike Hero's unrestricted run by three seconds and finishing well clear of the other three.

On the steep climb, 0.65 miles with 226 feet of gain and a 12% maximum grade, the Thunder Pro was equally impressive, reaching the top in 2:00 flat at an average of 19.5 mph. Fastest in the group again. Whatever you make of the spec sheet, the climbing power is real.

This claim held. On throttle power alone the Thunder Pro reached a GPS-verified 35 mph, exactly as advertised, and it holds that speed comfortably. The fat tires, long wheelbase and full suspension also keep it stable at this speed. The display is optimistic, reading about 3 mph higher than our external GPS.

A reminder: 35 mph under motor power exceeds e-bike classifications everywhere in the US. Ride accordingly.

Measured indoors with the rear wheel spinning unloaded at 20 mph, the Jasion hub registered 73.4 dB(A). Out on the road it's more audible at full power on the climbs, but never the dominant sound over wind and tires.

The cadence sensor needs three-quarters to a full pedal rotation before assist arrives from a standstill. On a bike that weighs nearly 100 lb, that makes unassisted starts difficult, especially on a hill. We ended up relying on the twist throttle to get moving, then pedaling once underway. The app can fix the assist tuning, but not the sensor's lag.

Jasion claims up to 90 miles, in the lowest assist level, with a 176 lb rider, on a flat route. On our standard loop, using max pedal assist with a 200 lb rider aboard, the Thunder Pro ST lasted 27.70 miles with 1,256 feet of elevation gain, at a rapid 18.88 mph average. That's in the lower half of the comparison group.

In its stock tune, using PAS 3, the Thunder Pro lasted 28.42 miles at an 18.14 mph average, nearly identical to the max assist result. That's no accident. In the stock settings, PAS 3 already provides close to full power. Both results sit in the lower half of the comparison group, and they tell you the honest range of this bike will be around 30 miles for most users.

Jasion claims up to 90 miles, in the lowest assist level. We test every e-bike at maximum assist, and for most bikes we add a second medium-assist range test. The better of the Thunder Pro's two results, 28.42 miles in PAS 3, is 32% of Jasion's claim. We did not ride the lowest PAS levels to empty, as this isn't how most people ride. The average fat-tire e-bike reaches 57% of its claimed range on this protocol. Even granting Jasion its ideal conditions (a lighter rider, a flat route, the lowest assist level), 90 miles does not look achievable.

Dividing battery capacity by measured range shows how far a bike stretches every watt-hour, and it exposes what all that speed and weight cost. At 37.5 Wh per mile, the Thunder Pro is among the five least efficient fat-tire e-bikes we've tested, roughly 30% above the fat-tire average. Physics sends the bill — 98 lb, 4-inch tires and 35 mph don't come free.

The 20Ah battery is charged by a small 2A charger, and the math is unforgiving. By our calculation a full charge takes about 10 hours (the 20Ah battery divided by the charger's 2A output). That is in line with Jasion's 10-hour claim and among the slowest in our database, nearly four hours longer than the 6.3-hour average. Plan on overnight charging, every time.

The 52V, 20Ah pack is removable and both the bike and battery are UL-certified, which is good news at this price. One caution from testing is that when the motor is at high output, the battery gauge drops, sometimes as far as 50%, recovering after a minute of rest. Expect some range anxiety until you learn to ignore it.

The unbranded two-piston hydraulic discs with 180 mm rotors brought the Thunder Pro from 20 mph to a complete stop in 21 feet, the longest distance in the comparison group, and 1.5 feet beyond the fat-tire average. This isn't a poor result, but we'd hope for more stopping power from a bike that can reach 35 mph.

The safety package is one of the bike's strengths: a decent headlight that put out 187 lux at 15 feet on our center-beam measurement, a rear light with brake activation, turn signals, and a horn.

Riding the Thunder Pro

The Thunder Pro is a massive, heavy e-bike loaded with accessories, but once moving, the weight mostly disappears. It accelerates smoothly under throttle, the torque delivery is tempered rather than snappy, and at speed it feels stable. The full suspension provides real comfort benefits over broken pavement and light off-road paths.

Push harder and the budget suspension hardware announces itself. The rear shock is very firm, resulting in a harsh feel over harder impacts. The budget fork also blows through its travel easily and dives under hard braking. In stock tune the pedal assist is poorly spaced. PAS 1 pushed us to 10–11 mph, PAS 2 to about 20 mph, and levels 3–5 all demand a cadence too high to contribute anything (the app fixes this). One more quirk: the bottom bracket sits low to the ground, and in tight turns it's easy to scrape a pedal.

On our stability run we ride the bike straight at speed, take our hands off the bars to check for shimmy, shift our weight, corner, and deliberately shake the bike to see whether we can start a wobble or a wander. At a sustained 35 mph, the Thunder Pro stayed composed.

The fat tires and full suspension help the Thunder Pro stay comfortable over broken pavement. The limits are in the details. The rear shock's short 40 mm stroke is harsh and firm, too stiff to add any real cushioning over bigger hits, and the grips are hard plastic: uncomfortable from the first mile and prone to slipping.

Where the Thunder Pro sits on the spectrum from fully upright to fully aggressive:

No. Jasion claims one frame size fits riders from 5'5" to 7'2", a 21-inch span served by a 4-inch saddle-height range. At 6'0" with a 33" inseam, our tester needed the seatpost at full extension. Riders over about 6'1" won't achieve proper leg extension, never mind riders approaching 7 feet.

The seatpost is the only meaningful adjustment. The 700 mm bar is fixed, and the cockpit is already crowded, with a seven-button keypad, thumb shifter, twist throttle, two mirrors and all the wiring competing for space. There's little room to make this bike fit you better. You adapt to it.

Jasion claims 82.5 lb but with the fenders, rack, lights, mirrors and tail bag fitted, our scale read 98 lb, the heaviest in this comparison group and the second-heaviest of the 18 fat-tire e-bikes we've tested. That weight is a real ownership cost. The bike is challenging to lift, won't fit most e-bike racks, and needs serious storage space. Thankfully, you don't feel most of it once moving.

The steel frame is available as a step-over or the step-through we tested, and nothing about the finish felt fragile during our test period. Integration is another matter. With a seven-button keypad, shifter, throttle, mirrors and externally routed wiring, there's a lot going on, and the cockpit looks and feels busy.

The Shimano Tourney 7-speed with a 48t chainring and 14–28t freewheel is entry-level hardware that shifts adequately, but the gearing simply can't keep up with the motor. Meaningful pedaling ends around 20 mph. Above that you're ghost pedaling at a cadence too high to add anything while the hub does the work. On a 35 mph bike, that's a big mismatch.

The 26"×4" Chaoyang puncture-resistant tires grip well on pavement and light gravel. The Thunder Pro comes with an impressive number of accessories for the price: full-coverage fenders, a rear rack, front and rear lights with turn signals and brake activation, a horn, plus mirrors and a tail bag as limited-time promotional gifts.

The centrally mounted display is easy to read even in direct sunlight. Two caveats: it reads about 3 mph above external GPS, and it's operated through a seven-button keypad on an already crowded bar.

Most bikes at this price don't include an app at all, and on the Thunder Pro, the app is essential. It adjusts the top speed of every assist level, the overall top speed, and sets the throttle to match the chosen PAS level. Five minutes of tinkering turned the poorly tuned stock setup into properly spaced assist. It stops at speed caps, though: there is no deeper customization of how the motor delivers its power, which is what keeps the app from a 5/5. On first connect, the app's settings didn't match how the bike behaved. Adjust and re-save them once, and everything syncs.

Our Thunder Pro ST arrived without damage or missing parts, a relief given how many online customer reports mention shipping damage and assembly issues. The bike ships mostly assembled, with the front wheel, handlebars, pedals, and the accessory pile left to install. The box includes tools and QR codes for the user manual, app, and quick-start guide. One person took 1 hour 17 minutes to get it road-ready. The accessories, not the bike, take the time.

Every brand we review gets the same test. We send one short, everyday support question through the brand's public support channel, from a regular customer account with no BikeRide affiliation, so the test is equal for everyone. We then time how long the first useful reply takes, counting weekday hours only. Jasion's auto-reply warns of a 1–3 business day queue, but the first useful answer arrived in 32 hours.

The mechanical side is as standard as it gets. A 7-speed freewheel, chain, brake pads, tubes and tires are cheap and available everywhere. The e-side (motor, battery, display, controller) is Jasion-proprietary and only available from the brand, which sells online with no dealer network. Full suspension plus the accessory pile also means more bolts to keep tight than a typical commuter.

Full suspension, hydraulic disc brakes, a 1,040 Wh battery, and a complete accessory package at this price is a lot of hardware per dollar. It goes without saying, the individual parts are budget-tier.

Weighing everything we measured against the price at the time of publication: verified 35 mph, group-best climbs, a 1,040 Wh battery, full suspension and every accessory included. On hardware per dollar the Thunder Pro is excellent. What it costs you is range, plenty of garage space, and a spec sheet you have to double-check.