Decathlon is running a limited-time promotion on its UB400B electric mountain bike, a full-suspension model aimed at riders who want comfort on rough trails and efficiency on daily commutes. With a hefty discount knocking €400 off the price, it suddenly looks far more tempting for anyone thinking about switching to assisted pedalling.
The deal: a high-spec e-MTB made more affordable
The Decathlon UB400B electric mountain bike was originally listed at €1,899. The current promotion cuts that by €400, bringing the price down to €1,499. For a full-suspension e-MTB with a large battery and hydraulic brakes, that places it in a very competitive bracket.
The UB400B drops from €1,899 to €1,499, making a full-suspension electric MTB with a 720 Wh battery far more accessible.
This price point will attract riders who want more than an entry-level commuter e-bike but do not want to pay premium-brand prices that can easily exceed €3,000. The UB400B targets a middle ground: decent components, trail-ready geometry and enough range for long days out.
Key specs at a glance
Decathlon’s UB400B is described as an electric mountain bike built for mixed use: city streets during the week, forest paths or gravel tracks at the weekend. On paper, it packs a solid set of components aimed at confidence and comfort.
- Bafang 250 W rear-hub motor with assistance up to 25 km/h
- 48 V, 15 Ah removable battery (720 Wh) integrated into the frame
- Advertised range up to 140 km in Eco mode
- Front and rear suspension for full-suspension comfort
- Hydraulic disc brakes
- 27.5-inch wheels with Maxxis Forekaster tyres
- LCD display showing speed, distance and assistance level
- Maximum rider and load capacity of 125 kg
With a 720 Wh battery and up to 140 km of claimed range, the UB400B is aimed at riders who hate worrying about charge levels.
A closer look at the motor and battery
The UB400B uses a 250 W Bafang motor mounted in the rear wheel hub. That makes it a legal pedelec under EU rules, with assistance cutting off at 25 km/h. Rear-hub motors tend to be simpler and often more affordable than mid-drive systems, and they usually require less maintenance.
Paired with that motor is a 48 V, 15 Ah lithium-ion battery, integrated into the frame but still removable for charging. Its total capacity of 720 Wh is generous for this price segment. Decathlon claims up to 140 km of range in Eco mode, which is the lowest assistance level.
What the range claim means in real life
Real-world range depends heavily on rider weight, terrain, wind, temperature and how often you push the higher assistance levels. Here’s a rough idea of what that 720 Wh pack could offer:
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| Use case | Assistance level | Approx. range |
|---|---|---|
| Flat urban commute | Eco / low | 80–140 km |
| Mixed road and gravel | Medium | 50–90 km |
| Hilly off-road ride | High / turbo | 30–60 km |
For many riders, that means charging once or twice a week instead of after every trip, especially for shorter commutes under 20 km per day.
Comfort: why full suspension matters on an e-MTB
Unlike hardtail e-bikes, the UB400B has suspension at both the front and rear. That design aims to reduce fatigue by absorbing bumps, roots and potholes. When you add the extra weight of a motor and battery, suspension becomes more than just a luxury.
Full suspension helps keep the bike stable on rough surfaces, which is particularly useful when you are travelling quicker with electric assistance.
The rear suspension is especially helpful on broken tracks and forest paths, keeping the rear wheel planted and improving traction. Combined with the Maxxis Forekaster tyres, which are known for their grip on loose terrain, the UB400B targets riders who want to leave tarmac without being punished for it.
Brakes, tyres and handling
The UB400B is equipped with hydraulic disc brakes, which tend to offer more consistent stopping power and better modulation than mechanical discs. That matters on an e-bike, since the extra weight can make stopping distances longer if braking is weak.
The 27.5-inch wheels strike a balance between agility and stability. They are often chosen for trail riding where quick changes of direction are frequent. The Maxxis Forekaster tyres provide an all-round tread that can deal with mud, gravel and hardpack, but they remain usable on asphalt.
Who this bike really suits
Decathlon positions the UB400B for both beginners and more experienced riders. The motor support makes longer climbs manageable, while the comfortable suspension and upright, ergonomic riding position help those who are less fit or returning to cycling after a long break.
- Urban riders who want a tough bike that withstands potholes and kerbs
- Leisure cyclists who enjoy weekend rides on forest paths and towpaths
- Newcomers to mountain biking who want confidence on descents without going into high-end territory
- Heavier riders needing a frame rated up to 125 kg of total load
The LCD display from Bafang allows riders to monitor speed, distance, battery level and assistance mode at a glance. That helps manage range, especially on longer outings where you do not want to run out of juice far from home.
How the promotion changes the equation
At its original price, the UB400B had to compete directly with bikes from specialists and emerging direct-to-consumer brands. The €400 reduction makes the maths look very different. A 720 Wh battery alone can significantly raise the cost of an e-bike, and full suspension typically pushes models into a higher tier.
Dropping to €1,499 places the UB400B among the more attractive full-suspension options for riders prioritising battery capacity and comfort.
For buyers comparing models, the choice often comes down to trade-offs: motor type, suspension, range, and brand reputation. A rear-hub motor is not as refined as a good mid-drive for steep technical climbs, but many riders prioritise simplicity and cost over that last bit of performance.
What to check before buying an electric mountain bike
Anyone tempted by this discount should still run through a few checks before committing. The UB400B is designed as an all-round e-MTB, but no single bike suits everyone perfectly.
- Frame size: make sure the geometry and size match your height and inseam to avoid discomfort or knee pain.
- Charging setup: if you live in a flat, confirm that you can remove the battery easily and take it indoors.
- Local rules: in many countries, 25 km/h pedelecs can use cycle paths, while faster “speed pedelecs” cannot. The UB400B stays within the usual legal limit.
- Weight: full-suspension e-MTBs are heavy. If you need to carry it up stairs regularly, factor that in.
Prospective riders should also ask about servicing. Bafang motors and hydraulic brakes usually require basic maintenance every year, especially if the bike is used off-road in wet conditions.
Some useful concepts for new e-bike riders
For those new to electric bikes, a few terms on the spec sheet can seem vague. “Wh” stands for watt-hours and describes battery capacity. A 720 Wh battery can, in theory, deliver 720 watts for one hour, or 360 watts for two hours. In practice, assistance is not constant, but the number offers a simple way to compare different models.
“Pedelec” refers to an e-bike that only assists while you are pedalling. The UB400B falls into this category: there is no throttle, and assistance cuts at 25 km/h. That keeps it closer to a traditional bicycle in legal terms and typically avoids registration and insurance requirements that apply to mopeds.
For many riders, an e-MTB such as the UB400B changes how often they ride. Steep hills feel less daunting, longer routes become realistic after work, and joint strain is reduced, especially for older cyclists. Combined with a decent discount, that can be enough to push hesitant buyers from “maybe one day” to “this season”.