Why are fatbikes dangerous?
You see them all over town: fatbikes with their rugged looks and extra-wide tires . They look like little monsters, very popular especially with young people who want to geen scooter. But behind this cool look lies a less pleasant reality. Fatbikes are more often involved in accidents than conventional e-bikes - and the reasons are mainly technical.
Written by : Hanna Stevens | 14 november 2025 | Reading time: 4 minutes
More about the author: Hanna Stevens
Hanna is an avid cyclist who loves exploring new routes and sharing her experiences to inspire others to get on their bikes more often.
Key findings
- Their weight of 30-35 kg extends braking distance
- Torque of 40-80 Nm makes for hard-to-control acceleration
- 4-inch tires lack grip in the wet and at high speeds
- Many models can be unbridled at 35-45 km/h
- Brakes and lighting often inadequate on low-cost models
- Very popular with young people, with little traffic experience
Table of contents
The weight problem: why braking becomes more difficult
This sudden acceleration: when the engine reacts too quickly
Wide tires : perfect in the sand, less so in town
The problem with unbridling: faster than the law allows
Brakes and lighting: details that count
Young people and urban environments: a risky combination
How can I make a safer choice?
The weight problem: why braking becomes more difficult
Take a classic urban e-bike: it weighs around 23 kg. A fatbike? Easily 32 to 35 kg. You feel the extra weight not only when you have to carry it, but also, and above all, in your safety.
Consequences of the extra weight :
- Longer braking distance, especially on wet surfaces
- More effort to turn or avoid an obstacle
- Slower reactions to unexpected events
- Difficult to control at low speeds
During our reconditioning checks, we found this out time and again: on dry asphalt, fatbikes still brake correctly, but as soon as the ground gets wet, the stopping distance increases dramatically. And there's the problem: if a pedestrian suddenly crosses or a car brakes, you simply don't have those extra metres.
This sudden acceleration: when the engine reacts too quickly
Many fatbikes are equipped with motors developing 50 to 80 Nm of torque. This technical term simply means: a lot of power. As soon as you pedal, the bike leaps forward as if you were being pushed.
For an experienced cyclist, it's fun and dynamic. For a 14-year-old on his first e-bike? It's often surprising, even dangerous.
Why high torque increases risk:
- Sudden acceleration on start-up
- Difficulty dosing in turns
- The need for constant anticipation
- Little progressiveness in assistance
Wide tires : perfect in the sand, less so in town
The 4-inch tires are designed for sand, snow or mud. There, they excel. But on smooth asphalt, wet slabs or, worse, streetcar tracks? They become a hazard.
The contact surface is large, ideal on soft ground. But in the city, this same contact surface causes slow steering. If you need to avoid a car or pothole quickly, the bike reacts with delay.
Problems of wide tires in urban areas :
- Less responsive steering for quick corrections
- Slips when cornering on wet surfaces
- Instability on streetcar tracks or metal plates
- Low pressure (0.5-1 bar) deforms the tire when cornering
Our technicians often see the same problem: inadequate pressure leading to unstable behavior. That's why we systematically adjust the pressure when we recondition a fatbike.
The problem with unbridling: faster than the law allows
Here's the trickiest part. In Belgium and the Netherlands, an e-bike can develop a maximum of 250 W and provide assistance at speeds of up to 25 km/h.. Beyond that, the engine must shut down. That's the law.
But many inexpensive fatbikes are easy to unbridle. A few clicks in an app or a USB cable, and you're suddenly riding at 40 km/h. Sounds cool, but it's extremely dangerous.
Why an unbridled fatbike is dangerous:
- Brakes not designed to exceed 30 km/h
- unstable tires at high speed
- No helmet, insurance or plate required
- Motorists don't expect a "bike" travelling at moped speed
- Risk of seizure and fine
Legal requirements: what is and isn't allowed
| Type of bike | Max. power | Maximum speed | Headset | Insurance | Plate |
|---|---|---|---|---|---|
| Electric bike | 250 W | 25 km/h | No | No | No |
| Speed-pedelec | 500-4000 W | 45 km/h | Yes | Yes | Yes |
| Unbridled Fatbike (illegal) | Variable | 35-45 km/h | Mostly no | No | No |
Brakes and lighting: details that count
Many inexpensive fatbikes use mechanical disc brakes. These heat up faster, deform more easily and brake less strongly than hydraulic brakes. On a 32 kg bike, this is a real problem.
Differences between brake types :
- Mechanical disc brakes: less expensive, less powerful, require more maintenance
- Hydraulic brakes: more powerful, more reliable, better control for a heavy bike
Lighting is another problem. Many models feature stylish but inadequate LEDs: too dim, misdirected or poorly placed. Belgian (FOD Mobilité) and Dutch standards require real front and rear lighting. Not for style, but to be seen at night.
Young people and urban environments: a risky combination
Fatbikes are particularly appealing to 12-18 year-olds, a group that still lacks road experience. They underestimate braking distances, have difficulty correcting sudden acceleration and often ride side by side.
Risk factors for young cyclists:
- Little traffic experience
- Poor estimation of stopping distances
- Group riding, distractions
- Insufficient reflexes in the face of sudden acceleration
- Overconfident at times
In cities like Amsterdam, Ghent or Antwerp, cycle paths are narrow, with sharp bends, streetcar tracks and pedestrians crossing. Wide handlebars, a heavy bike and little experience? It's the perfect recipe for accidents. See also our article on child safety on a fatbike.
How can I make a safer choice?
If you still want to buy a fatbike, check these points:
Essential safety features :
- Hydraulic disc brakes
- CE marking (European conformity)
- Standard-compliant front/rear lighting
- Battery tested with capacity report
- Stable frame without weld defects
- 250 W nominal motor (compliant)
Recommended technical specifications :
- Weight: maks. 30-32 kg
- Battery: 480-720 Wh (tested)
- Engine torque: 40-60 Nm (sufficient for city driving)
- tires : pressure set between 0.8-1.2 bar
Comparison: fatbike vs. urban e-bike
| Features | Fatbike | Urban e-bike |
|---|---|---|
| Weight | 30-35 kg | 22-26 kg |
| tires width | 4,0-4,8" | 37-50 mm |
| Engine torque | 40-80 Nm | 35-65 Nm |
| Braking (wet) | Longer | Shorter |
| Management responsiveness | Slower | More vivid |
| Ideal use | Off-road, leisure | Daily commuting |
| Risk of unbridling | High | Low |
How to reduce risk
- Choose hydraulic brakes and good lighting
- Check CE conformity and a tested battery
- Do not exceed 25 km/h (legal limit)
- Consider a refurbished , controlled model
- Allow beginners to practice in a quiet environment
Fatbikes look great and feel great to ride. But they're heavier, more powerful and less predictable than conventional e-bikes. If you buy one, make a well-considered choice: good brakes, correct lighting, tested battery. Don't override it. And if you're not sure: opt for a refurbished model with warranty. At least you know the technology is reliable. Read our guide on what to look for before buying a fatbike.
Stay safe, even if your bike looks super cool.
FAQ
Are fatbikes more dangerous than conventional e-bikes?
Yes, because of their weight, wide tires and sharper acceleration, braking distances are longer and stability is lower on asphalt.
Can fatbikes go faster than 25 km/h?
Not unless they're officially licensed as speed-pedelec, with compulsory license plate and helmet.
Are wide tires safer?
Not in urban environments. They are designed for sand and snow, not wet asphalt.
Why are fatbikes often unbridled?
Their controller is easy to unlock. But it's illegal and dangerous.
How to recognize a safe fatbike?
Check for hydraulic brakes, good lighting, CE marking and a tested battery.