SUNNIGOO B4 Folding Fat Tyre Electric Bike – 250W, 48V 12.5Ah (600Wh), 20x4.0 Tyres, Hydraulic Disc Brakes

A 250W folding fat-tyre e-bike — black or military green

The SUNNIGOO B4 takes the folding fat-tyre formula and gives it a taller, sturdier stance: 20x4.0 tyres on a 6061 aluminium folding frame, a 48V 600Wh removable battery, hydraulic disc brakes and a 15 kg rear rack. It is the one to pick if you want the extra load margin and a colour that does not mind a bit of dust.

The removable 48V 12.5Ah (600Wh) pack delivers 50 to 80 km of assisted riding, charges in about 6 hours and locks with a key so it can be charged indoors.

Why Riders Choose the SUNNIGOO B4

48V 250W rear hub motor	Rated at the 250 W continuous ceiling, so it pulls away cleanly on a slope and holds 25 km/h into a headwind — and stays a legal bicycle everywhere in the EU.
Folds in under a minute	The folding frame and folding pedals shrink it to a fraction of its length, so it fits a car boot, a lift, a hallway or a boat locker — no roof rack, no garage required.
48V 12.5Ah (600Wh), removable	About 50% more capacity than the 36V packs on comparably priced city e-bikes. Comes out with a key so you can charge it indoors.
20 x 4.0 inch Chaoyang fat tyres	A wide contact patch that rolls over gravel, wet cobbles, sand, kerbs and tram tracks instead of catching in them — the reason riders buy a fat-tyre bike in the first place.
Hydraulic disc brakes, front and rear	Fingertip stopping power in the wet, with far less lever effort than mechanical discs. A loaded bike needs brakes you can trust at the bottom of a hill.
Shimano 7-speed gearing	You pick the cadence and the motor handles the load. Ride past the 25 km/h cut-off on the flat using almost no battery.
Rack, mudguards and lights as standard	An aluminium rear rack rated to 15 kg, full-length mudguards and front and rear LED lights are all fitted — ready for the commute or the weekly shop.
EN 15194 pedal assist	No licence, no insurance, no registration — legally a bicycle across the EU, the UK and Switzerland.

SUNNIGOO B4 Full Specifications

Brand	SUNNIGOO
Model	B4
Colour	Black / Military Green
Motor	48V 250W rear hub motor
Battery	48V 12.5Ah (600Wh) lithium-ion, removable with key lock
Charger	54.6V 2.0A, 100-240V, European standard round plug
Charging time	Approx. 6 hours
Display	LCD display with PAS indicator, battery level and light control
Assist type	Pedal assist (PAS) – the motor runs only while you pedal
Top assist speed	25 km/h (EU / UK legal pedal-assist cut-off)
Assist range	50–80 km depending on load, terrain and assist level
Frame	6061 aluminium alloy, folding
Fork	Suspension fork
Gears	Shimano 7-speed with rear derailleur
Brakes	Front and rear hydraulic disc brakes
Tyres	20 x 4.0 inch Chaoyang fat tyres
Rear rack	Aluminium, max load 15 kg
Mudguards	Aluminium, front and rear
Lights	Front LED (48V DC); rear LED with integrated battery
Saddle	Soft city saddle
Folding	Yes – folding frame and pedals for transport and storage
Max load	100 kg
Net weight	30 kg
Gross weight	37 kg
Package size	146 x 28 x 70 cm
Assembly	85% pre-assembled – front wheel, pedals, seat and handlebar to fit

Is the B4 Legal to Ride in Europe?

• 250 W and 25 km/h — The motor is rated at 250 W continuous and assistance cuts out at 25 km/h, which is the EN 15194 EPAC limit.
• Pedal assist only — There is no throttle. The motor only adds power while you are pedalling, so the bike is classified as a bicycle rather than a moped.
• No licence, insurance or registration — As an EPAC it needs none of them in the EU, the UK or Switzerland.
• Check your local rules — National rules vary in detail (for example, some countries require a bell or reflectors, and Germany treats EPACs as bicycles under the eKFV). Always check your local traffic code before riding.

600Wh is roughly half again the capacity of the 36V packs fitted to most city e-bikes at this price. It comes out of the frame with a key, so you can charge it at your desk instead of running a cable to the bike.

What’s in the Box

• SUNNIGOO e-bike (85% pre-assembled, front wheel to fit)
• 48V 12.5Ah battery pack with 2 keys
• 54.6V 2.0A charger (European round plug)
• Aluminium rear rack and front / rear mudguards (fitted)
• Front and rear LED lights (fitted)
• Hex key set and wrenches
• Pedals (marked L / R)
• User manual

Built and Supported by SUNNIGOO

The B4 is sold under the SUNNIGOO brand. Every bike is inspected before it leaves the factory, ships from our EU warehouse with local delivery and local returns, and is backed by our own support team for setup questions, tuning and spare parts — you deal with us, not with a marketplace seller.

Frequently Asked Questions

How far can the B4 go on one charge?

Around 50–80 km of assisted riding, depending on your weight, how much you carry, the terrain and the assist level. Flat routes at the lowest level sit at the top of that range; hilly rides with a loaded rack sit at the bottom.

Does it fold?

Yes. The frame folds and the pedals fold with it, so the bike shrinks to a fraction of its length for a car boot, a lift or a hallway. Everything you need to fold and unfold it is fitted to the bike — no tools.

Does it have a throttle?

No. The B4 is pedal-assist only — the motor adds power while you pedal and stops helping at 25 km/h. That is what keeps it a legal bicycle in Europe rather than a moped.

Why fat tyres instead of normal ones?

A 4.0-inch tyre runs at low pressure and puts a much wider patch of rubber on the road, so it grips on wet cobbles, gravel, sand and broken asphalt, and it soaks up kerbs and potholes that would jar a narrow-wheeled bike.

Is the battery removable, and how long does it take to charge?

Yes — the 48V 12.5Ah pack unlocks with a key and slides out, so you can charge it indoors. A full charge from empty takes about 6 hours with the supplied 54.6V 2.0A charger.

How much can it carry?

Total load capacity is 100 kg including the rider, and the aluminium rear rack is rated to 15 kg. The rack, mudguards and front and rear lights are all fitted as standard.

What colours are available?

Available in Black and Military Green — both colours ship from our EU warehouse.

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SUNNIGOO B4 — folding fat tyre electric bike for adults. 48V 250W rear hub motor, removable 48V 12.5Ah (600Wh) battery, Shimano 7-speed, 20x4.0 Chaoyang fat tyres, suspension fork and hydraulic disc brakes. EN 15194 pedal assist, 25 km/h cut-off. Shipped from our EU warehouse with fast local delivery and local returns.