Name: 72V 4000W Extreme Performance Ebike Motor Kit for MTB and Fat Tire Bike 55MPH+
Brand: KirbEbike
Price: 1380.0 GBP
Availability: InStock
Rating: 4.84 (19 reviews)

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power output

4000W | motor wheel

Battery Specs

72V 20AH LG | Lithium Battery

top speed

55MPH+ | Max Speed

range

30-40km | Range

motor weight

9.8kg | Motor Weight

Install Time

50 Minutes | Convert Your Bike

Voltage Peak

84V | Full Charged

charging

4 hours | Fast Recharge

torque

110Nm | Max Torque

Secure. Stable. Theft-Resistant.

Triangle Battery Installation Guide

Installing the triangle battery is simple and reliable, offering enhanced anti-theft protection, safety, and stability so your battery stays firmly in place and protected on every ride.

1

Install the Base Mount

Secure the base plate to the bike frame.

2

Attach the Clamps

Fasten the clamps to lock the base plate into place.

3

Mount the Battery

Slide the battery onto the base until it locks in place.

4

Lock and Secure

Tighten the screws and lock to complete installation.

FOC Controller for 1000W–4000W E-Bike Conversion Kits

Ultimate Control. Smarter Power. Waterproof by Design.

Tune speed, torque, throttle response, PAS levels, regenerative braking, and current limits through the Ride Power App for a fully customized ride. With a waterproof controller and a fully waterproof system, the kit is built for more reliable performance in all-weather riding.

App Control

Smart App Control

Weatherproof

Fully Waterproof System

Flexible Installation Design

Compact Design. Flexible Fit. Secure Installation.

Designed with a more compact shape, this battery takes up less space and fits more bike frames with ease. It supports Top Tube / Down Tube mounting, giving you more flexibility when planning your setup. Paired with the bracket and mounting plate system, installation is simpler, more secure, and better equipped for anti-theft protection, everyday safety, and ride stability.

Flexible

Tube Mounting

Secure

Bracket Lock

Secure Anti Theft Mount

Bracket Mounting for More Security, Stability, and Anti-Theft Protection

This battery uses a bracket mounting system for a more secure and stable installation. It stays firmly in place while riding and is less likely to shift or loosen over time. Supporting Top Tube / Down Tube mounting, it fits a wider range of bike frame layouts. The bracket design also adds an extra layer of anti-theft protection, giving you more confidence both while riding and when parked.

Stable

Bracket Mounting

Lockable

Parking Security

Secure

Anti-Theft Protection

Competition-Level Performance

EXTREME-GRADE 4000W POWERHOUSE

Unleash unprecedented speeds of 55+MPH and massive 110Nm torque with the KirbEbike 4000W Conversion Kit. Dominate steep climbs and conquer rough terrains with professional-grade torque output. Powered by an advanced 72V brushless direct drive motor and precision FOC sine wave controller, it's engineered for extreme commuting and off-road adventures.

4000W

Peak Power

55+MPH

Max Speed

110Nm

Torque

72V

Architecture

Engineered For Extreme Performance

High-Capacity Power System

Powered by Samsung 21700 50S cells cells, our 72V (84V full charge) 20AH battery delivers an impressive 30-40km range, 4 hours fast charging, and 800+ charge cycles. Military-grade construction with advanced thermal management ensures maximum reliability. Intelligent BMS system provides real-time monitoring and protection. Experience a 3-year lifespan, 60A max discharge for full 4000W compatibility, and professional-grade design.

30-40km

Range

800+

Cycles

4 hours

Fast Charging

60A

Discharge

Fast Charging & IP65 Protection

High Capacity, Fast Charging, and IP65 Waterproof Protection

Designed for everyday riding and outdoor use, the HS battery series combines high energy capacity with fast 4–5 hour charging and reliable IP65 waterproof protection, giving you more convenience and confidence in changing conditions.

Up to 1440Wh

High Capacity

IP65

Weatherproof

Professional-Grade Intelligence

Precision Control Hub

Premium 3.5" TFT display shows comprehensive data: speed metrics, trip computer, battery status, PAS levels and brake signals. Advanced 60A FOC controller with 18-MOSFET design delivers precise power control. Intelligent cruise control maintains your desired speed, while 6km/h walk assist mode helps navigate tight spaces. Complete with thermal protection and waterproof construction.
250W/25KM/H Speed Limited Function. Press the Up button of display two seconds to enter limted 250w. Press it again to off.

60A FOC

Controller

18-MOSFET

Design

3.5"

TFT Display

PAS

Levels

Waterproof Controller System

Fully Potted Waterproof Controller for Stable Power

Full resin potting protects the controller PCB from water, moisture, and vibration while improving heat dissipation. It helps extend controller life and keeps power output stable during daily riding.

100% PCB Waterproof

Full Resin Potting

Better Cooling

Longer Controller Life

Stable Output

Reinforced Components

Clear Wiring System

Color-Coded Connectors for Easy, Error-Free Installation

Different wire colors and dedicated connector shapes make each port easy to identify, helping reduce the risk of wrong wiring. High-current 5.5 bullet motor connectors and an XT90 battery connector support stable power delivery, while brake, throttle, display, Bluetooth APP, and anti-theft alarm ports provide full-function control for your ebike system.

Clear Wiring

Color-Coded Connectors

High-Current Ready

5.5 Bullet & XT90

Multi-Function Ports

Brake, Display, APP & Alarm

Transform Your Ride, Maximum Compatibility

Extreme Upgrade Package

50-minute installation for MTB and fat tire bikes. Universal fit for 26"-29" MTB and 20"-26" fat tires, perfect for both extreme off-road and daily commuting. Professional toolkit and torque arm included. Complete DIY guide ensures easy installation with no permanent modifications needed.

Universal MTB & Fat Tire Fit (26"-29", 20"-26")

All-Terrain Performance Ready

Professional Installation Kit

Heavy-Duty Mounting Hardware

Expert Support & Video Guide

Find Your Perfect Model

Best For

Fat Tire Kits

Off-Road

Motor Power

4000W

2500W-3000W

2000W

Full Charged Voltage

84V

71.4V

58.8V

Wheel Position

Rear Wheel

Wheel Size

20” /26” / 27.5”/ 29”

20” / 24” / 26” / 27.5” /28” / 29” / 700C

26” / 27.5” /28” / 29” / 700C

Bike Compatibility

MTB / Fat Bike / City Bike

MTB / Fat Bike / Road Bike / City Bike

Top Speed

55MPH+

45+MPH

55+MPH

Range

30-40km

40–55km

40-85km

Battery Required

72V 20AH LG

60V 20Ah

52V 25Ah / 52V 30Ah / 48V 30Ah / 52V 20Ah

Battery Included

Optional

Installation Level

Medium

Brake Compatibility

Disc Brake

Waterproof Cables

No

Yes

App Support

Yes

Best For

Fat Tire Kits

Off-Road

Motor Power

4000W

2500W-3000W

2000W

Full Charged Voltage

84V

71.4V

58.8V

Wheel Position

Rear Wheel

Wheel Size

20” /26” / 27.5”/ 29”

20” / 24” / 26” / 27.5” /28” / 29” / 700C

26” / 27.5” /28” / 29” / 700C

Bike Compatibility

MTB / Fat Bike / City Bike

MTB / Fat Bike / Road Bike / City Bike

Top Speed

55MPH+

45+MPH

55+MPH

Range

30-40km

40–55km

40-85km

Battery Required

72V 20AH LG

60V 20Ah

52V 25Ah / 52V 30Ah / 48V 30Ah / 52V 20Ah

Battery Included

Optional

Installation Level

Medium

Brake Compatibility

Disc Brake

Waterproof Cables

No

Yes

App Support

Yes

How to Turn ANY Bike Into a 72V 4000w MONSTER!!!

72V 4000W power system, delivering extreme speed and powerful performance. Equipped with a 72V 20Ah battery, ensuring long-lasting range, a 60A sine wave controller for a smooth and stable riding experience. 3kW MTX hub motor, pushing up to 4000W peak speed. Easy installation with no zip ties or Velcro required, keeping it clean and efficient.

What's in the kit?

What's included in the individual kit?

In the individual kit, you get everything you need to DIY your bike into an e-bike.

A 4000W powerful motor wheel, 48V-72V 60Amp FOC sinewave smart controller, 48V-72V TFT color display, 72V 20AH Lithium battery pack, 72V 5A Fast Charger, Twist Throttle with the key Lock, e-Brake levers and a good package with foam to protect all parts be safe.

In addition we provide free sweet service accessories, installation tools and additional parts.

What's in the kit?

What's included in the individual kit?

In the individual kit, you get everything you need to DIY your bike into an e-bike.

A 4000W powerful motor wheel, 48V-72V 60Amp FOC sinewave smart controller, 48V-72V TFT color display, 72V 20AH Lithium battery pack, 72V 5A Fast Charger, Twist Throttle with the key Lock, e-Brake levers and a good package with foam to protect all parts be safe.

In addition we provide free sweet service accessories, installation tools and additional parts.

Motor Wheel

1. MTX 39 Double Wall Aluminum Alloy Strong Rim. Black Color

2. 4000w Brushless Direct Drive Rear Wheel, 6.8kgs weight.

3. Black Paint Spokes anti-rust 12G 2.6mm with copper Nipples.

4. Dropouts: 135-142mm. Two Motors: One is for a 7s threaded sprocket, and The other is for Cassete 8s/9s/10s/11s sprocket.

5. Fit Disc Brake.

6. 55+MPH max speed.

7. CE, ROHS certificates.

72V 20AH LG Lithium Battery

1. 84VV Full Charged Voltage

2. 5A Fast Charger is included.

3. Samsung 21700 50S cells

4. USB mobilephone Charging

5. ON/OFF Switch

6. Battery Indicator. Precent.

7. Triangle Black Plastic Case.

Smart controller

1. 48V-72V 60Amp FOC

2. Sinewave 12 mosfets Controller.

3. Waterproof, Glues Inside.

4. Quick Release Cable.

5. Over Heating Protection.

6. Easy to Install with Tape Ties.

TFT color display 48V-72V

1. Color Display Design.

2. Battery Power Indicator.

3. Running Speed, Average Speed, Max Speed.

4. Single Mileage, Total Mileage.

5. PAS Levers, Brake Signal, Throttle Signal.

6. Cruise Function, 6KM/H Walk Function, and so on.

e-Brake levers

Electric Brake Lever to cut off the power when you press it.

Twist Throttle with the key Lock.

Easy installation、More sensitive 、more stable performance.

Free Accessories Included

Allen Tool Set

Crankset Remove Tool

Freewheel Remove Tool

Crankset Remove Tool

Wrench

Sweet Service Accessories

Brake sensor

Torque arm

ECMF

Frequently Asked Questions

Is a 4000W ebike kit legal in the UK?

Not on public roads at full power — but this kit switches to a fully legal 250W / 25 km/h mode in three seconds via Limit Mode. Ride to the trail legal, ride the trail unrestricted. Full power is for private land with the landowner’s permission.

What's the real-world range I can expect?

Typical range varies from 40-80km depending on your riding style. You'll get maximum range when cruising at moderate speeds with pedal assist. Aggressive riding at top speeds (80-90 km/h) will reduce range significantly. Factors like rider weight, terrain, and temperature all affect actual performance.

How long does installation really take?

While we advertise a 50-minute installation time, most experienced riders complete it in 1-2 hours. We provide comprehensive tools and step-by-step video guides. First-time installers may want to schedule 2-3 hours or seek professional help for optimal setup.

Will this fit my bike?

The kit is engineered for standard MTB frames (26"-29") and fat tire bikes (20"-26"). Most modern mountain bikes and fat bikes are compatible. However, carbon fiber frames and ultra-lightweight bikes aren't recommended due to the power output. Contact us with your specific bike model for confirmation.

About battery lifespan and charging

Using premium LG/Samsung cells, expect 800+ charge cycles over a 3-year lifespan with proper care. A full charge takes 4 hours 35 minutes. The intelligent BMS prevents overcharging and monitors cell health. The battery detaches easily for indoor charging.

Can I run it on a fat bike?

Yes — there is a dedicated 4-inch fat-tyre edition with the same battery and controller. It is the pick for beaches, snow and soft ground.

What about noise and reliability?

The brushless direct drive motor operates quietly compared to geared systems. Military-grade construction and waterproof design ensure durability. Most users report thousands of kilometers without issues when properly maintained.

How fast does it actually go?

47–53 mph (75–85 km/h) depending on wheel choice, terrain and rider weight. In legal mode: 15.5 mph, like every compliant e-bike.

What maintenance is required?

Regular maintenance includes checking motor connections, ensuring battery contacts are clean, and inspecting the torque arm. The controller and battery systems are sealed and maintenance-free. We recommend periodic firmware updates for optimal performance.

What warranty covers a kit this powerful?

The same as every KirbEbike kit: 1 year, serviced in the UK, US, the Netherlands. High power does not void it — abuse does, so fit the torque arms.

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Waiting for delivery

I have received the battery but I'm still Waiting for delivery of the wheel after 2x weeks.

⭐⭐⭐⭐⭐

Amazing product, I had some issues setting it up but the technician helped me all the way. Great services ⭐⭐⭐⭐⭐

Good product, I got best discount from GrabOn coupons

Must Buy!

Very good kit easy to fit I’m pretty satisfied thank you

Really smooth

The kit is quite and easy to install, goes faster than what the site saids and is a beast. With no ebike experience i installed this in 3 hours.

Kirbebike's 72V 4000W Extreme Performance Ebike Motor Kit for MTB and Fat Tire Bike 55MPH+

This kit is fast! Long lasting battery with plenty of power. This kit is an easy clean install! Great technical support group will answer all of your questions.

Easy to put on bike and very fast

better then they even say!

it took about 1h 30 with no experience and charging was not 4 hours it took about 2, top speed is also 95 mph plus with no weight. amazing kit

Faster than 5kW

Bought this as an entry into e-moto, just built a 5000w kit from another supplier, and its 5-10mph slower, would definitely recommend kirbebike's kit, never had an issue.

Holy crap this is fast asf (4 stars since most 5 stars are bots)

Long story short this has been hella amazing, I thought this would be situation of “ts pmo this gon take 3 months 💔 🌾🌾🌾” but actually the shipping and such was pretty reasonable, over all it took around a 2 weeks for the motor to arrive and another week for the battery if I’m not wrong.

The installation time on the website is pretty much a ‘professional estimation’ 😭 for me atleast I had to put some steel to make the battery fit but even without that, it took around a full days worth of getting everything on, could be that I am still an amateur at this but you’re mileage may vary.

When I was don’t, god damn from a 250w motor going 40kmh with little to no torque, to this absolute beauty of a kit is crazy like I had to go to the advanced settings and change the PAS from 5 to 9 and throttle strength from 5 to 2 becuase it just has so much god damn power right off the line. I have managed to reach 91kmh with the wind on this kit, I weigh 65kg and the bike without kit is 35kg, but is wear this was worth every single euro.

Last note is that the response time of customer service was like 9/10, it may take at most 2-3 days for them to answer but on average it was a couple of hours, this may be the only time that i have ever left a review but customer service was top notch, whenever i ask for the status of the battery or motor, they provide tracking information for you and for technical information, Jason really helped me a lot 🙏

Off-Road Kits

Commuting Kits

FAT Tire Kits

Road Legal Kits

500W–1000W

Mid Motor Kit

EZ Rider Kit

Battery

Accessories

72V 4000W Extreme Performance Ebike Motor Kit for MTB and Fat Tire Bike 55MPH+

Triangle Battery Installation Guide

Install the Base Mount

Attach the Clamps

Mount the Battery

Lock and Secure

Find Your Perfect Model

How to Turn ANY Bike Into a 72V 4000w MONSTER!!!

What's in the kit?

What's included in the individual kit?

What's in the kit?

What's included in the individual kit?

Free Accessories Included

Allen Tool Set

Sweet Service Accessories

Customer Reviews

Off-Road Kits

Commuting Kits

FAT Tire Kits

Road Legal Kits

500W–1000W

Mid Motor Kit

EZ Rider Kit

Battery

Accessories

72V 4000W Extreme Performance Ebike Motor Kit for MTB and Fat Tire Bike 55MPH+

Triangle Battery Installation Guide

Install the Base Mount

Attach the Clamps

Mount the Battery

Lock and Secure

Find Your Perfect Model

How to Turn ANY Bike Into a 72V 4000w MONSTER!!!

HS-II 72V20AH Battery

Taishan 72V20AH Battery

What's in the kit?

What's included in the individual kit?

What's in the kit?

What's included in the individual kit?

Free Accessories Included

Allen Tool Set

Sweet Service Accessories

Customer Reviews