French retail giant Decathlon is making a strong push in this category, cutting the price of a powerful full-suspension electric mountain bike built for long days, steep climbs, and rough trails.
A big discount on a serious electric MTB
Decathlon is currently running a major promotion on the UB400B, a full-suspension electric mountain bike aimed at riders who split their time between forest trails and everyday roads. The brand has knocked €500 off the list price, dropping it from €1,899 to €1,399.
Decathlon’s UB400B drops to €1,399 until December 1, 2025-saving €500 on a long-range, full-suspension e-MTB.
The offer runs until December 1, 2025 and is limited to Decathlon’s online store. The retailer is also promoting installment options, with payment split into three or four interest-free payments-clearly targeting riders who want a capable electric bike without stepping into premium-brand pricing.
A full-suspension e-MTB built for varied terrain
The UB400B is a full-suspension aluminum mountain bike, meaning both the front fork and rear end have suspension. This setup is designed to smooth out rocky trails, roots, and broken paths while giving the rider more grip and control.
Decathlon positions this model for riders who want to mix up their routes: technical forest singletrack one day, gravel paths or hilly country roads the next. Rather than a stripped-down urban e-bike, this is closer to a “go-anywhere” bike that still stays within European e-bike regulations.
Core specs at a glance
- Full-suspension aluminum frame rated up to 125 kg total load
- 48 V, 15 Ah removable battery (720 Wh) integrated into the frame
- Bafang 250 W rear-hub motor with assistance up to 25 km/h
- Hydraulic disc brakes: 180 mm rotor front, 160 mm rear
- 29-inch wheels with Maxxis Forecaster tires for mixed terrain
- LCD display with Bluetooth and app connectivity
With a 720 Wh battery and ECO mode, the UB400B is claimed to reach up to 140 km between charges.
Motor and battery: range for long days out
The centerpiece of the UB400B is its 48 V, 15 Ah battery, delivering a total capacity of 720 Wh. That’s generous for this price range, and it directly affects how far you can ride with power assistance.
Decathlon claims up to 140 km of range in ECO mode. That figure assumes moderate assistance, mixed terrain, and a rider who is doing a meaningful share of the pedaling. Push the motor harder in hilly terrain, or ride consistently in a high assistance setting, and real-world range will drop-but there’s still enough capacity for most riders to spend a full day on the bike.
The battery sits inside the frame and can be removed for charging, which is convenient for riders who store their bike in a garage or shared bike room but want to charge the battery indoors. It also makes long-term maintenance easier, since batteries are often the first component replaced on an e-bike that sees heavy use.
Bafang rear-hub motor for smooth assistance
Power comes from a 250 W Bafang motor mounted in the rear hub. This differs from the mid-drive systems found on higher-end e-MTBs, but it keeps costs down, simplifies maintenance, and still provides solid assistance up to the legal European limit of 25 km/h.
Hub motors typically deliver a consistent push and are less sensitive to gear choice. For riders new to e-bikes, that can feel intuitive: you pedal, the bike responds with a noticeable but controlled boost, making steep ramps and long climbs much more manageable.
Control and safety on challenging trails
For braking, Decathlon chose hydraulic disc brakes with a 180 mm rotor up front and a 160 mm rotor in the rear. This setup is common on trail bikes, providing strong stopping power and better modulation than mechanical disc brakes or rim brakes-especially in wet conditions.
Hydraulic discs and 29-inch tires mean the UB400B is built to handle wet roots, loose stone, and fast descents with more confidence.
The 29-inch wheels wear Maxxis Forecaster tires, a popular choice for mixed terrain. Their tread pattern balances grip on soft ground with rolling speed on hardpack or pavement. Riders who switch between commuting and trail rides will likely appreciate not having to constantly swap tires.
Comfort and connectivity
The aluminum frame is rated to carry up to 125 kg, including the rider and any cargo. That makes it suitable for heavier riders or those who want to carry bikepacking bags or a sturdy backpack without exceeding the bike’s limits.
An LCD handlebar display shows data like speed, battery level, and assistance mode. With built-in Bluetooth, riders can connect a smartphone through a dedicated app to log rides, track energy use, and adjust settings. For anyone using the bike for both fitness and transportation, that added data can help with route planning and charging routines.
| Feature | UB400B specification |
|---|---|
| Motor | Bafang 250 W rear hub, 25 km/h assist |
| Battery | 48 V, 15 Ah (720 Wh), removable |
| Range (claimed) | Up to 140 km in ECO mode |
| Brakes | Hydraulic discs, 180 mm front / 160 mm rear |
| Wheels & tires | 29″ wheels, Maxxis Forecaster tires |
| Frame | Aluminum, full suspension, up to 125 kg load |
| Price during promo | €1,399 (down from €1,899) |
Who the Decathlon UB400B really suits
The UB400B targets a wide range of riders: trail-curious newcomers, occasional mountain bikers who want electric help, and commuters who like the idea of a tough bike that can handle weekend punishment. With its suspension and chunky tires, it won’t be the fastest option on pure pavement, but it adds comfort over potholes and cobblestones.
For country riders, the large battery stands out. A 720 Wh pack with a realistic mixed-use range of 70–100 km can cover long loops with steep hills without triggering range anxiety. For city riders, it can mean several days of commuting between charges, depending on distance and assistance level.
The UB400B is best for riders who want one bike for weekday commuting and weekend off-road escapes, instead of owning separate bikes.
What the discount changes in practice
At its original €1,899 price, the UB400B sat in a crowded mid-range e-MTB market. At €1,399, it becomes much more competitive-especially considering the full-suspension design and high-capacity battery. For many shoppers, that €500 difference is what turns “maybe” into a purchase.
With installment plans split into three or four payments, the psychological hurdle drops again. For example, spread over four months, the monthly cost is roughly €350-putting a long-range, off-road-capable e-bike within reach of riders who might otherwise settle for a simpler hardtail.
Key terms and what they mean for real riding
Some e-bike jargon hides simple concepts. “Wh” (watt-hours), for example, describes the total energy stored in a battery. A 720 Wh pack can deliver 720 watts for one hour, or 360 watts for two hours, and so on. If you typically ride with moderate assistance drawing 250–300 watts, you can estimate how long support will last before you need to recharge.
“Full suspension” can also sound like marketing until you hit a rock garden at speed. Having both front and rear suspension lets the bike track the ground more closely. The tires maintain better contact with the trail, which means more control and fewer harsh impacts to your wrists and lower back. For older riders or anyone with joint issues, that comfort can make the difference between a one-hour ride and a three-hour ride.
Practical scenarios: commuting, fitness, and leisure
Picture a 20 km daily round-trip commute that mixes city streets with a riverside path. Using mid-level assistance, many UB400B riders could commute for two or three days before needing a recharge. On Fridays, they could switch to ECO mode and head out for a 50 km countryside loop without stressing about range.
For fitness, bikes like this often work better than people expect. Riders tend to go out more often and ride longer because the fear of blowing up on a climb disappears. You can set assistance low, keep your heart rate in a target zone, and still take on hilly terrain. Over time, many owners report lowering the assistance level as fitness improves-using electric power as a backup rather than a crutch.
There are also risks to consider: higher speeds and heavier bikes require better braking technique and more awareness in traffic. New riders should spend time on quieter roads or easy trails to get used to how quickly the UB400B accelerates when the motor engages and how it behaves during hard braking. Once that feel is dialed in, the combination of electric assistance, capable suspension, and a large battery can open up routes that would have felt out of reach on a traditional bike.
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