Electric bikes are not only hard to come by, they are also getting more expensive. So it's no surprise that more and more people are considering the seemingly genius idea of building their own electric bikes. But is it legal to build your own e-bike? What are the legal requirements and potential pitfalls? We're here to clear things up.

The demand for e-bikes in 2020 presents the industry with unexpected challenges. In our article, "Cycling Boom in Crisis," we explain the pros and cons of this change. Over the past few weeks, more questions and instructions for DIY fat tire bike accessories have been circulating on social media. But what can you actually do and be aware of if you want to modify or build your own e-bike? Quick warning: In order to accurately describe everything, it is important to review the laws and regulations as well as the DIN standards and various guidelines. This article is informative and interesting, but also a bit complicated.

Build your own e-bike? Is that allowed? If so, what are the consequences? We tell you what is allowed, what is not, and what is still a grey area.

Electric bikes or electric bikes, what are we talking about?

When we talk about an e-bike, we are referring to the legal definition of an e-bike, which is classified as equivalent to a regular bicycle. So you don't need a driver's license or insurance to ride. The motor (whose nominal power limit is 250 W) supports pedal input from the rider and can reach a top speed of 25 km/h. Internationally, the term EPAC (Power Assisted cycle) is also used. This is where it starts to get interesting. By attaching a motor to the bike, it becomes a smart electric vehicle, subject to different standards and rules. For example, both the EU Machinery Directive and the EMC Directive apply to intelligent electric vehicles. So this article describes the types of e-bikes you can buy at a bike store, with the exception of those you build yourself. Illegal chip-tuned e-bikes will not be discussed here.

By attaching a motor to the bike, it becomes a smart electric vehicle, subject to different standards and rules.

Transfer to the police? We summarized the legal and insurance-related aspects of e-bike tuning in a separate article.

What does Germany's Zweirad-Industrie-Verband (ZIV) think of homemade electric bikes?

We asked Ernst Brust, ZIV's managing director, to provide us with some legal justification. "Intelligent electric vehicles built by private individuals for their own use and used on public roads also fall under the mechanical and EMC directive and must be tested according to DIN EN 15194-2017. This also includes the CE mark for smart electric vehicles."

Ernst Brust is ZIV's managing director and a publicly appointed and sworn bicycle expert.

But what exactly does DIN EN 15194-2017 mean for an e-bike? What must you prove when approving a bicycle? Industry leaders including Zweiradmechaniker-Handwerk, Velotec.de, VSF., Zedler Institute and ZIV have produced a document (in German only) outlining what you need to know about modifying electric drives. In it, they listed the conditions needed to meet the criteria and the documents that must be provided:

Risk analysis

Material list and disposal instructions

Proof of operational stability of all safety-related components

Electromagnetic Compatibility test (Electromagnetic Compatibility)

Operating and electrical safety certificates

Original manual printed in local language

Assessment of conformity

Declaration of compliance

The nameplate meets the CE standard

Modifications by dealers or end users may have a variety of legal consequences:

To commit a regulatory or criminal offence

Distributor's liability for personal injury or property damage

Loss of public liability insurance

Loss of trading license

The consequences of competition law

Glossary - Explain the most important terms

(German) Product Safety Law

The Product Safety Act ensures that each manufacturer keeps its bikes safe during use, regardless of any required standards. For e-bike manufacturers, this means they have to exceed ISO 4210 and EN 15194. In doing so, manufacturers must position themselves in light of current scientific and technological developments, as meeting the criteria will not automatically exempt them from liability claims.

Directive for Machinery 2006/42/EC

Essentially, every smart electric vehicle sold in the EU must have an EU compliance declaration. This is usually printed in a manual or provided as a separate document. Paragraph 2 (i) of this directive clearly states that "[...] Any natural or legal person who places on the market or puts into use machinery covered by this Directive or partially completed machinery shall be deemed to be a manufacturer." In short, this means that individuals must also follow mechanical instructions. If you meet its requirements, you can provide the CE mark for the machine (in this case, the smart electric vehicle). If you're tech-savvy and want to read more about the subject, you can find more information about mechanical instructions here.

Within the EU, intelligent electric vehicles built by individuals for private use also fall under the Machines and EMC Directive and must be tested in accordance with DIN EN 15194-2017. This also applies to the no-trade exchange of homemade electric bicycles, in which the gift of a bicycle is equivalent to placing it on the EU market and fulfilling all the relevant requirements. This includes CE-compliant nameplates on smart electric vehicles. (Jens Muller)

Bdsf-accredited machine safety expert Jens Muller gave us a detailed look at the legislation for self-built electric mountain bikes.

EMC Directive 2014/30/EU

The Electromagnetic Compatibility (EMC) Directive 2014/30/EC regulates almost all electronic devices on the EU market. The manufacturer of the equipment is obliged to demonstrate that the equipment complies with the requirements through conformity assessment tests. In turn, they must produce technical documents, provide operating manuals and safety information, and affix the CE mark.

CE Mark

CE marking is the responsibility of the manufacturer, and independent testing of the product is rarely done. First of all, the mark is a promise. It says the product complies with relevant EU standards and has passed corresponding tests. Every bike you buy online or in a store must have a CE mark.

By the CE mark on the seat tube here, manufacturer SCOTT confirms that this e-bike is an EPAC (Electric Power Assisted Bicycle) that meets the relevant requirements.

Declaration of compliance

A declaration of compliance is a manufacturer's or importer's way of proving that a product complies with EU directives and standards.

The data required in a claim varies by product type.

The responsibility usually rests with the manufacturer.

If a manufacturer or importer fails to provide a declaration of compliance for their product, they can be fined up to 30,000 euros.

International standard

Two standards, ISO 4210 and EN 15194, apply to electric bicycles. Almost all frame and bicycle parts around the world are tested and approved against these standards.

ISO 4210

ISO 4210 Bicycles (for European and international use) describes standardized tests that define industry testing protocols. However, ISO 4210 assumes a maximum system weight (bike + rider + luggage) of 100 kg.

EN 15194

In addition to ISO 4210, EN 15194 also covers electric bicycles. EN 15194 applies to EPAC (electric assisted bicycle) equipped with pedals and electric motors for use on public roads. EN 15194 also defines the test protocol, but the load is increased and the maximum system weight is 120 kg. However, the standard is primarily based on roads and foot bikes, and is primarily aimed at ensuring that electrical drives and components meet minimum requirements and work together properly.

By attaching a motor to the bike, it becomes an electric bike and is again classified as a machine, which means that different standards and rules apply, including mechanical instructions.

If you have a frame and a motor, then assembling them will be easy for most mechanical hobbyists.

However, it is important to understand the potential impacts before you convert or build. You have to decide for yourself if it's worth it.

What are the options for making your own electric bike?

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

Convert a bike to an electric bike using a modification kit.

Build your own e-bike with a frame set.

Build an electric bike from parts.

1. Use a modification kit to convert an existing bike into an electric bike.

If you can find a dealer who can convert your beloved bike (for ISO 4210) into an electric bike (also for EN 15194), then you are off the hook because the dealer is responsible for the conversion. Legally, dealers who create a new product must perform all of the above certifications themselves. They have to do this for each individual transformation they make. If they do not, then they will assume all risks and full responsibility at their own expense. Even the best bike mechanic can't tell with absolute certainty whether a frame or component is suitable for modification. With older bikes, factors such as material fatigue and bike handling must also be considered. Any dealer acknowledges the high risk of doing so and should be aware of that fact.

We may have had a lot of requests from customers over the years, but in the end, we decided not to offer a legitimate conversion service, which would have turned us into a manufacturer, which would have had a number of consequences. (Marcus Heinz)

Marcus Heinz, workshop manager at Leonberg, E-Bike Center, which employs about 20 people. By converting a standard bike to an electric bike, he would have to take full responsibility for its manufacturer.

Another option is to purchase a conversion kit from your dealer or online and do the job yourself. But here you also have to realize that the person who technically modifies the bike becomes the manufacturer of the machine. If you want to build a legal bike, then even as an individual you have to test the bike. The modified intelligent electric vehicles must meet the requirements of the Mechanical Directive 2006/16/EC.

Tip: Check if it's worth upgrading your bike to an electric bike first. When it comes to sporty electric mountain bikes, we have our doubts, and it's definitely wiser to buy a used bike. You can find everything you need to know in our Buyer's guide.

2. Build your own e-bike frame

Buying a frame set from a manufacturer like Specialized is obviously more elegant, but also more expensive. After deciding what you want, you get a frame in which a motor, battery, and shock absorber are already installed. Then you simply add wheels, brakes, forks, bars, and other components to complete the build.

The S-Works Turbo Levo frame set is available from Specialized for €5,999. We spoke with Dominik Geyer, global head of turbocharged practice at Specialized, about the factors that must be considered when buying a Levo frame set to build your very own e-bike.

E-MOUNTAINBIKE: Did you receive the EC Compliance Declaration and CE mark when you purchased the frame?

Major: Yes. We sell frame sets as "incomplete machines" that include all the required technical documentation and company statements. The CE mark is not required here.

E-MOUNTAINBIKE: Is a professional user manual also available?

Major: Yes. This can be used as a guide for our client's own documentation and as a reference for possible builds.

E-MOUNTAINBIKE: What must customers be aware of when purchasing surplus parts for their frame sets?

Specialization: The customer must ensure that the components are compatible with the frame set and that they are suitable for the intended use of the entire bike.

E-MOUNTAINBIKE: After assembling the parts with the CE mark, did the customer meet the requirements of the mechanical directive, or did they need to do anything else?

Professional: The customer only needs to ensure that the whole bike complies with the terms of the currently applicable directives and has been assessed in accordance with these directives.

Dominik Geyer, head of Specialized's global turbocharging practice, tells us what to look for when buying a frame.

Tip: Personalising your own e-bike can be exciting, but for people who are not skilled mechanics or don't have the right tools, we recommend that you purchase a complete bike, not least because any cost savings will be limited.

3. Build an electric bike from various parts

Can you assemble your own electric bicycle? Yes, in principle you can build anything you want. If you want to legally drive on public roads with it, then, as mentioned before, even as an individual, you have to follow the mechanical instructions. However, failure to comply with the standards (see glossary) does not usually result in sanctions against private groups, which is a distinct grey area. It is important that you do not exceed the 25 km/h assist limit and that the bike does not go faster than 6 km/h using the accelerator/push assist without pedaling. Otherwise, bicycles would be considered motor vehicles and regulated under stricter guidelines. When assembling the bike yourself, you must know which motor to use because it must fit into the frame. Unfortunately, you will soon reach the limits of this adventure when trying to buy a motor. Large companies such as Bosch, Shimano, Brose, Yamaha, FAZUA, Mahle and TQ do not sell their motors directly to the end consumer.