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Haibike HardFour Kids eBike 2021 Yamaha

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Who is this bike suitable for?

This one's pretty obvious - The Haibike HardFour 2021 eBike is for kids who require that little bit of assistance!
This 24" wheeled unisex kids electric bike is suitable for children ranging from the age of 8 onward. A kids specific chassis and refined Yamaha eBike system.

The SDURO HardFour is a revelation for families who want to ride together. Compared to this bike, a PlayStation totally loses its appeal! - Enduro Magazine

New Features

The new HardFour 2021, finally we have a 24" kids electric bike. Do your children get fed up and tired mid way through the ride? Do you want to ride further with your family? Or does your child require some support?

The new Haibike HardFour 2021 is the answer!

The HardFour offers refined kids geometry and a smaller 24" wheel. Suitable for boys or girls with an average age of 8 years old and up.

This simple spec'd electric bike is great for children and Haibike have included a refined version of the 2021 Yamaha system, learn more further down the page.

Shimano Altus on HardFour 2021 Kids eBike

The 2021 HardFour features a 9 speed Shimano Altus gear system with simple to use trigger shifters to give the kids full versatility across varied climbs and descents. Remember with crank drive you can use the gears with the assistance.

The smaller 24" wheels on the HardFour offer kids full control and stability. Small enough to manoeuvre around, but big enough to take on a full day's ride and follow the parents through varied terrain.

Tektro Brakes on HardFour 2021 Kids eBike

Although kids sized wheels, Haibike have built them with decent disc hubs and Rodi alloy, double wall, rims.

The 2021 HardFour comes with Tektro hydraulic disc brakes. Simple to use and fairly maintenance free, it's a good option on this 24" kid's bike. With the electric assistance we want to ensure braking power remains solid.

For 2021 the 24" Schwalbe Billy Bonkers tyres are both lightweight & durable in their construction, they allow a faster rolling resistance while maintaining grip at the same time. 

A good choice for a mixture of surfaces.

We are excited about this children's electric bike. A proper German crank drive Yamaha eBike. Finally you can take the kids on a full ride out without the stresses and strains of them getting worn out after a short distance. 

The Yamaha controls are very simple to operate. There's only three buttons, one to turn it on/off and two to adjust the assist up/down.

Yamaha Kids eBike System 2021

Yamaha PW-TE eBike System

The new 2021 Haibike HardFour is powered by the latest Yamaha electric bike system. This 250w motor offers up to 280% assistance and peaks at 60Nm of restricted torque (on this kids version).

The assistance is set in 4 levels on the kids version - 'Eco +', 'Eco', 'Standard' & 'High'. This allows the child to fine tune the amount of assistance required. We also see a new set of controls that loose the LCD screen in replace of simple on / off power and assistance, easy to use buttons.

The Haibike Hard Four 2021 kids eBike is offered with the 400Wh Yamaha battery to give a full day's ride time. Now your son / daughter can join you for the longer rides too!

On the Kids version the assistance speed is lowered down to 12.5mph. We want children to have fun whilst maintaining a safe pace. We also remove the walk assist and simplify the levels to make it as user friendly as possible.

Whats included?


This electric bike comes fully set-up by our workshop technicians. You can be sure that every aspect of the eBike has been dialled in for optimum performance. All our electric bikes arrive with a user manual, keys, charger & free follow up service within 3 months.

Support on the Haibike HardFour Kids eBike 2021

Our electric bikes also include a 5yr warranty on the frame, 2yr warranty on all the electrics & 1yr warranty on the components. In the event of a problem, we handle all warranty claims in-house. We can also offer worldwide support.

E-bikeshop is a UK Yamaha Electric Bike Service Center and our in house workshop is now exclusively reserved for our own eBike customers. We also have parts / spares to hand should they be required.

*Range is dependant on many factors inc rider weight, wind, hills, terrain etc. For a better estimate, please use our range calculator. 

*Pre-order service: Take advantage of our pre-order service which places you in the queue to obtain a bike as soon as it is available. Orders are fulfilled on a first come served, queued basis. Dates are predicted production times and with all manufacturing dates can move back and forth. Specifications can change and images are artists impressions.

Free Electric Bike Insurance Cover

FREE 14 Days Electric Bike Cover

We've exclusively teamed up with Bikmo to offer 14 days free electric bike insurance when you purchase your new electric bike with

You'll be covered for eBike theft, accessories, crash damage, clothing/headgear, accidental damage, public liability and Bikmo will even cover the cost of getting you home as a result of damage or theft.

The perfect package to get you started with your new eBike without the need for any worry or hassle. Of course, you'll have the no obligation option to continue your insurance over after the initial period.

To get this exclusive special offer, simply tick the checkbox in the checkout. 

*You must meet all of the standard Bikmo eligibility criteria and understand the Bikmo locking requirements. You can find this info on the dedicated page here

Customer Reviews

Review submitted on previous model: This is a really excellent bike. Myself and the Mrs both have eBikes and my 9 year old son always struggled with longer rides/hills this limited us to very short rides on flat roads only. Now he is off like a rocket hills are no longer an issue for him and he no longer constantly complains about being tired.

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General Bike Specifications


Aluminium 6061 with Internal Cable Routing


SR Suntour XCR LO, Lockout, 63mm, Tapered

Rear Shock



Tektro M282 160mm


Shimano Altus M2010 9-Speed Triggers

Rear Mech

Shimano Altus M2010 9-Speed


Shimano HG200, 11-36 Teeth, 9-Speed


KMC X9 9-Speed


Rodi Alloy Rims, Haibike TheHub++


Schwalbe Billy Bonkers 24 x 2.00"


Haibike TopFlat Bar 31.8mm 640mm


Haibike TheStem 31.8mm


A-Head, Alloy, Tapered


Haibike Alloy Post, 31.6mm


Haibike TheSaddle Junior


20 Kg

Electric Bike Specifications


Yamaha Lithium Ionen 36 Volt, 400 Wh, with BMS Management


Yamaha Side Switch multi functional LCD display


Yamaha PW-TE Crank Drive 36V 250 W, 60Nm


30 - 80 miles of power assisted range, depending on terrain

Further Information


The most frequently asked questions on this eBike -

These questions relate to this bike. You can find a full F.A.Q on general eBike & website questions by clicking here.

What sizes is this bike available in?
The Haibike HardFour 2021 is available in one frame size for kids: 24" Wheels 34cm (13") frame.

Is this bike in stock now?
The stock status is shown at the top of this page next to the price. If the stock level is shown as 'Pre-Order' this means it is a new model arriving soon, you can see an expected date at the top of each bike description.

Are there any colour options?
No, the HardFour 2021 electric bike is only available in the colour shown.

Where can I find a geometry chart of this bike?
You can find the geometry chart of each bike by clicking on the 'Downloads' tab of each bike.

How fast will this bike go?
This bike will assist you to 12.5mph. From there you can pedal faster, but with no assistance.

Where can this bike be ridden?
Under UK law a rider needs to be aged at least 14 to ride an Electrically Assisted bike on the road or any other public place.

Where is this bike made?

Can I try the bike before I buy?
Yes of course, you can visit, we can talk you through your riding style and requirements and offer expert advice as to which model to select. We will be able to advise particular eBikes and talk them through in more detail. We also give you the opportunity to ride crank drive bikes so you can get a feel for them prior to purchase. 

At e-bikeshop we work by appointment only, so we can talk to each customer on an individual basis to give the best advice possible. If you like the bike, you have the option to take it away there and then with any accessories selected fitted and a full fitting session on the bike itself. We ask you to go for a short ride on the bike to make sure you are happy with the setup and also able to answer any operational questions you may have. 

If you cannot find the answer you are looking for, please do not hesitate to get in touch.
Remember you can find a full F.A.Q on general electric bike & website questions by clicking here.

The following links will open PDF files in a new tab -


Yamaha eBike System Overview - Yamaha eBike System Overview

Winora Bike Manual - Winora Group eBike Manual

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Finance Options

The prices below do not include any additional products, product options or shipping costs.
To pay by finance select the finance option during the checkout process.
Finance is only available for UK residents.

Finance Options
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The above values are best estimates, Final pricing will be confirmed on the V12 Retail Finance application. The UK Electric Bike Company Ltd is registered in England and Wales 08775019. Registered office: 12 Borelli Yard, Farnham, Surrey, GU9 7NU. The UK Electric Bike Company Ltd acts as a credit broker and only offers credit products from Secure Trust Bank PLC trading as V12 Retail Finance. The UK Electric Bike Company Ltd is authorised and regulated by the Financial Conduct Authority. Our firm reference number is 659966. Credit provided subject to age and status.