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Follow This Step to DIY An Electric Bicycle

DIY an Electric Bicycle is not a easy task, but ebikes aren’t just difficult to get hold of at the moment but are also getting more expensive. As such, it’s not surprising that increasing numbers of people are considering the apparently genius idea of building their own ebike. But is it legal to build your own eMTB? What are the legal requirements and potential pitfalls? We clarify things here.

What are you actually allowed to do and what do you need to pay attention to if you want to convert or build your own ebike? A quick warning: to be able to describe everything accurately, it’s important to look at legal regulations as well as DIN standards and various guidelines in detail. This article will be informative and interesting, but a little complicated too.

DIY An Electric Bicycles or pedelec, what are we talking about?

When we talk about an ebike, we mean the legal definition of a pedelec, which is classified as equivalent to a normal bicycle. As such, you don’t need a licence or insurance to ride one.

The motor (with its nominal power limited to 250 W) supports the rider’s pedalling input up to a maximum speed of 25 km/h. Internationally, the term EPAC (Electrically Power Assisted Cycle) is also used. This is where it starts to get interesting.

By adding a motor to a bike, it becomes a pedelec, for which different standards and rules apply. For example, the EU Machinery and EMC directives both apply to pedelecs.

So, this article is about the kind of ebike you can buy at your bike shop, except one that you’ve built yourself. Illegal, chip-tuned ebikes won’t be discussed here.

By adding a motor to a bike, it becomes a pedelec, for which different standards and rules apply.

What does the german Zweirad-Industrie-Verband (ZIV) say about self-built ebikes?

We asked ZIV Managing Director, Ernst Brust, to give us some legal grounding. “Pedelecs that are built by private individuals for their own use and that are used on public roads also fall under the Machinery and EMC directives and have to be tested according to the DIN EN 15194-2017 standard. That also includes providing a CE mark for the pedelec.”

But what exactly does DIN EN 15194-2017 for ebikes encompass? What do you have to demonstrate when having a bike approved? Industry leaders including Zweiradmechaniker-Handwerk, velotech.de, VSF., Zedler Institute and ZIV have produced a document (German only) outlining what you need to know about retrofitting E-drives.

DIY An electric bicycle in it, they list what is required to meet the standard and which documents must be provided:

  1. Risk analysis
  2. Bill of materials and disposal instructions
  3. Proof of operational stability of all safety-relevant parts
  4. EMC testing (Electromagnetic Compatibility) for the whole vehicle
  5. Proof of operational and electrical safety
  6. Printed original manual in local language
  7. Conformity assessment
  8. Declaration of conformity
  9. CE compliant nameplate

There are several possible legal consequences for retrofitting by a dealer or end-user:

  1. Committing regulatory or criminal offences
  2. Liability of the dealer for personal injury or damage to property
  3. Loss of public liability insurance cover
  4. Loss of licence to trade
  5. Consequences under competition law

Glossary – The most important terms explained

  • Machinery Directive 2006/42/EC

    Fundamentally, every pedelec that is sold in the EU has to have an EU conformity declaration. This is usually printed in the manual or provided as a separate document. Paragraph 2 (i) of this Directive clearly states, “[…] any natural or legal person who places on the market or puts into service machinery or partly completed machinery covered by this Directive shall be considered a manufacturer.” Put simply, that means that private individuals also have to stick to the Machinery Directive. If you meet its requirements, you are allowed to furnish the machine, in this case, the pedelec, with a CE mark.

  • (German) Product Safety Act

    The Product Safety Act ensures that every manufacturer guarantees the safety of their bikes during use, independent of any required standards. For eMTB manufacturers that means they have to exceed ISO 4210 and EN 15194. In doing so, the manufacturer has to orient themselves by the current scientific and technological development as meeting standards doesn’t automatically exempt them from liability claims.

  • EMC Directive 2014/30/EU
    The 2014/30/EC Directive on Electromagnetic Compatibility (EMC) regulates almost all electric devices in the EU market. Manufacturers of equipment are obliged to prove via conformity assessment testing that the device meets requirements. In turn, they must produce technical documents, provide a manual of operation together with safety information and place the CE marking.

  • ISO 4210

    ISO 4210 for bicycles (applicable in Europe and internationally) describes standardised tests that define the testing protocols for the industry. However, ISO 4210 assumes a maximum system weight (bike + rider + luggage) of 100 kg.

  • EN 15194

    Alongside ISO 4210, EN 15194 additionally covers ebikes. EN 15194 applies to EPAC (Electric Power Assisted Cycles) which are equipped with pedals and an electric motor and that get used on public roads. EN 15194 also defines testing protocols, though with increased loads and a maximum system weight of 120 kg. However, this standard is based primarily on road and trekking bikes and is mainly intended to ensure that E-drives and components meet minimum requirements and work properly together.

The data required in the declaration varies depending on the type of product.

Liability is usually assumed by the manufacturer.If the manufacturer or importer fail to provide a conformity declaration for their product, they can be fined up to € 30,000.

International standards

Two standards, ISO 4210 and EN 15194 apply to ebikes. Pretty much all frames and bike parts worldwide are tested and approved according to these standards.

Conformity declaration

A conformity declaration is the manufacturer’s or importer’s way of demonstrating compliance of a product with EU directives and standards.

CE marking

CE marking is the responsibility of the manufacturer and only rarely is the product independently tested. In the first instance, this mark is a type of promise. It says that a product meets relevant EU standards and has been tested accordingly. Every bike that you buy online or in a shop must have a CE mark.

What options are there for self-built ebikes?

For this article we considered the following three scenarios in more detail:

  • Converting a bicycle to an ebike with a retrofit kit.
  • Building an ebike up yourself with a frameset.
  • Building up an ebike from individual parts.

DIY An Electric Bicycle Conversion

Step 1: The E Bike Kit


Here is the kit used in the conversions. You have a rear wheel motor, controller, thumb operated throttle, on/off switch, brake levers with kill switches (not used), and battery to control cable.

The brake levers had kill switches on them. Since the throttle is thumb operated, the kill switches and extra wires did not seem necessary. This proved true later on. If you need to stop, you just let go of the thumb throttle, and the motor stops. It is intuitive.

Step 2: The Donor Bike


The donor bike needs to be a sturdy frame. It is said that cheaper bikes make good e bike frames. This may be true from the motor point of view, but if you want to pedal the bike too, maybe not such a good idea.

Step 3: Install Motor

Installing the rear wheel motor was pretty straightforward except for the shims, which proved to be some work.

The motor and wheel appear very high quality, durable and well built. However, they are an inch or so wider than the old rear wheel and the bike frame dropouts.

I just took the frame, placed it on the ground, and pulled it out a bit. This may not be the best way to do it, but It worked. Just watch out how far you pull as the frame will bend easier than you think and is not as easy to push back into original position.

Step 4: Install Switches

The next thing to do is install the switches. This is pretty easy except for removing your old handlebar grips, if you have them.

One trick to removing old grips fairly easily is to take a screwdriver and pry open the grips, and then pour some soapy water into the opening. Wiggle the grips around (you might need a pair of pliers or vise grips) until they break loose, pour in more water and so on.

Before you take your old gear shifters off, look and see where the switches will be mounted. The thumb throttle lever on the kit described here was a little short, so you want to get it as close as possible to the gear/brake lever as possible.

The on/off switch can be easily mounted on the other side.

After mounting the switches, carefully dress the wires back to the motor area. Make sure to leave a little slack around the headset/headtube of your bike. This is to allow the handlebars to turn freely from side to side.

Step 5: Install Battery Box

The next thing to do is to decide what kind of battery box you want, measure your battery and controller, select the box, drill some holes, cut a wire opening, and install the box.

Step 6: Line Box

Line the box with foam or other insulator of your choice.

Note the position of the controller in the back and the battery in front. This is in case of a fast stop, the circuit board on the back end (nearest the controller) will suffer the least.

Step 7: Finish and Test

Well, this is the beginning of the fun!

After the kit is installed, be sure to road test it. The gears on the new freewheel probably need adjusting, as well as the rear brakes.

If you are looking for a new way of commuting or want a healthier lifestyle, we are here to help you. Visit our website to learn more about electric bikes and electric scooter or please leave information to us.

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