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Retrofit electric bike – how to turn a bio bike into an e-bike
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A new e-bike is expensive. Especially if you are looking to save money and have a bike you are happy with, it might seem tempting to upgrade your bicycle. You can get bike conversion kits in a variety of price ranges. Nevertheless, is it worth it?
That depends. Here is what you need to know and how to go about converting your bike into a pedelec.
Converting your bike to an e-bike: Important questions to ask beforehand
Before getting seriously into bike-to-electric-bike conversion and buying an electric bike conversion kit for your bike, you should answer some basic questions.
Is my bicycle suitable?
The most important question first. In fact, not every old bicycle can be converted into an e-bike, at least if you do not want to endanger your life and the lives of others.
The reason for this is that having a motor significantly increases the demands placed on the bike. Therefore, pay attention to two factors when you consider turning your bike into an e-bike:
- Stability: the motor and a battery add weight. In addition, there are the forces to which the bike is subjected by the motor drive. It is therefore crucial that your bicycle is robust, especially the frame and fork. Also, note that the material of old bikes can show signs of fatigue. If your bike was robust 8 years ago, it is not necessarily so today. Here a consultation can make sense.
- Brakes: The extra weight also challenges the brakes of bicycles. This is especially true if you are traveling significantly faster than before, supported by the motor. Brakes with cable are quickly overtaxed in this situation. Replace them rather against the hydraulic rim or disc brakes.
So it can be stated:
Converting to an electric bike is an option if you have a good, sturdy, and not too old bicycle. It is better not to load the student bike you inherited from your dad with a motor and a battery.
Tip: Bike conversion kits vary in weight. Anything between about three to 10 kilos is possible here. Keep this criterion in mind when choosing.
How much should I spend?
The short answer: Not too little. While you can get conversion kits on Amazon and other portals for as little as 250 euros, their quality usually matches the price. The first worthwhile models are currently available for a little more than 700 Euros, and the prices are open at the top. If the retrofit kit costs a few thousand Euros, you can assume high quality. But then the question arises as to why you don’t just buy an e-bike.
What do I need to be able to do?
You don’t need great craftsmanship for every conversion kit. However, a little experience in tinkering or replacing parts on bicycles is an advantage. Alternatively, it is possible to hire a professional to do the conversion. However, this incurs additional costs. Also, bicycle shops usually insist on installing their own conversion kit. The chances of you being able to select a retrofit kit yourself for installation by an expert are slim.
Tip: If you are not a passionate mechanic, choose your aftermarket kit based on how easy it is to install. Reviews from other customers are more informative here than manufacturer promises.
Tips for choosing an e-bike conversion kit
Are you sure that your bicycle is suitable for transforming into an e-bike and want to spend the money on an appropriate kit? Then we come to the question of what you should look for when choosing.
What are retrofit kits made of?
The scope of retrofit kits differs. However, this is mainly due to cables and connections. The central components that should never be missing are the battery, motor, and control electronics. This is where the differences begin.
The battery – range and mounting location
The battery of electric bikes influences how far you can go with it. Accordingly, it is worth taking a close look at the capacity of the battery. In some cases, manufacturers offer sets with different batteries for converting e-bikes. In addition, batteries differ according to where they are attached. For example, they can be attached to the luggage rack or to the seat tube. This affects the center of gravity and the range. For example, a battery on the luggage carrier scores points for easy handling. On the other hand, the handling is usually better when the battery is attached to the down tube.
Which motor is best suited?
The decisive factor in the selection of the motor is the place of attachment. Here, three variants can be decided:
- Motors that are attached to the front wheel or its hubs (front wheel hub motor).
- Motors for the rear wheel (rear wheel hub motor)
- Middle motors
Each of these variants has its advantages and disadvantages

Front motors:
are easy to install, but make for an awkward center of gravity, especially at higher speeds.

Rear motors:
are very suitable for retrofitting e electric bikes, are quiet and provide good power transmission. However, they cannot be combined with a coaster brake.

Mid-mounted motors:
Offer a great riding experience and use little power, but put more strain on the chain and are usually more expensive.
Most who want to convert bikes to electric bikes opt for a rear motor, but a mid-motor is also good. We would only advise against front-mounted motors for safety reasons and because of the poor ride feel.
Important: In order for your e-bike to pass as a normal e-bike and not exceed a top speed of 25 km/h, it must not have more than 250 watts of power. Otherwise, you have an S-pedelec. This requires insurance and license plates. It also requires a moped or motor vehicle driver’s license and a helmet.
What else you should look out for
Once you have inspected the battery and motor, there are two things you should pay attention to:
- Mounting: We have already addressed this point. How easy or difficult it is to convert a bicycle into an electric bike varies greatly. Especially if you are not a born screwdriver, find out how complex the installation is.
- Compatibility: Not every conversion kit fits every e-bike. Therefore, make sure that the kit is compatible with your bike.
Finally, of course, the price also plays a role. There is no hard and fast rule here, except that caution is advised with bargains. Also, always remember that the conversion is only worthwhile if it is not more expensive than a new electric bike.
3 manufacturers of electric bike conversion kits in comparison
Meanwhile, so many manufacturers offer conversion kits for e-bikes that we cannot possibly list them all.
But we want to pick out three recommendable ones as examples:
Ansmann
Still comparatively new as a manufacturer of retrofit kits is the company Ansmann. However, it has already made a name for itself in the field of battery packs and rechargeable batteries. With Ansmann, you have the choice between different drive types and mounting locations. At around 1000 euros, the kits are in the midfield in terms of price. In return, they offer reliable quality, a pleasantly quiet motor, and high compatibility.
high quality
pleasantly quiet
choice between different models
Bafang
Bafang is known for its wide range of rear and front motors for converting bikes. In some cases, motors of the Chinese manufacturer are also used as original equipment for e-bikes. Here, you will almost certainly find a compatible model and can choose between different performance levels and equipment, including modern on-board computers. Nevertheless, many retrofit kits from Bafang are not expensive and easy to get. Accordingly, Bafang kits are popular. Only the installation requires patience and skill and must be done by yourself. In addition, not every Bafang set complies with the STVZO. If you are unsure, get advice!
Great price-performance ratio
Large selection
Caution: Not every set complies with the STVZO
Pendix
You will have to dig deep into your pocket for Pendix conversion kits, at least if you want to cover longer distances. Then the fun costs around 1500 euros or – for even more range – 200 euros more. However, there is hardly an electric bike conversion kit that looks as appealing as this one. In addition, you can switch between different driving modes directly on the battery and Pendix also sets standards in terms of volume. In the meantime, there are also two significantly cheaper variants from the same supplier, but with a very limited range. They are suitable, for example, if you only want electronic support on inclines. The Pendix eDrive1000 is suitable for tours lasting several days. However, this device costs more than 2000 euros.
High quality
Beautiful optics
Almost silent
High price
Think about the theft protection for your new e-bike
When you convert a bike into an e-bike, its value increases. Unfortunately, not only for you, but also for bike thieves. It is, therefore, all the more important that you protect your pedelec well against theft.
Three components, in particular, are essential for e-bikes:
- at least one high-quality lock, perhaps with an integrated alarm system
- one or more component locks to protect the battery and co. from theft
- a GPS tracker to track your e-bike live and get it back in case of emergency

To equip your retrofitted pedelec with a GPS tracker, you can get the BikeTrax GPS tracker from PowUnity in several variants:
- Engine-specific trackers, for example, for an electric bike with a motor from Bosch, Brose, Shimano, or Yamaha.
- The GPS Tracker Universal, which lives up to its name and is suitable for a wide variety of technology applications where a connection to a power supply is possible – perfect for a converted electric bike.
- In the near future, there will also be a GPS tracker specifically for motors from Bafang.
With all variants, you benefit from the following advantages for modern theft protection:
- You are immediately alerted via the associated app if your electric bike moves unintentionally.
- You can track your bicycle throughout Europe via a modern app in real-time and share the location data with friends, family, or the police, for example. So the chance is high that you will get a stolen bike back, a big difference from a bike without a GPS tracker.
- You also benefit from valuable additional features like a bike tracking sheet in the accompanying PowUnity app.
GPS trackers have revolutionized bike theft protection. Read our article “Iot GPS Tracker – the Internet of Things in your bike” and learn more about how they work and what makes them different.
Retrofit e-bike – advantages and disadvantages
Now we come back to a question we raised initially: Is it even advisable to convert a bike into an e-bike, or isn’t it better to save up for a new pedelec right away?
In fact, a conversion has some advantages:
Retrofitting is more sustainable than buying new. After all, the resource consumption in producing a bike conversion kit is significantly lower than in producing an electric bike.
Depending on which e-bike conversion kit you choose, you can save money this way, especially when buying an expensive pedelec.
You can continue to ride your usual bicycle. This is also an argument for some people to choose retrofitting.
On the other hand, there are also disadvantages:
On a new (good) electric bike, all components are matched to each other. This ensures a pleasant riding experience and a high load capacity. A converted bicycle cannot necessarily keep up.
Meanwhile, solid e-bikes are already available at low prices. Then the difference to a bike conversion kit is often small, especially if you choose an expensive kit from a manufacturer like Pendix. This is especially true when you consider the time it takes to convert.
With many conversion kits, tinkering is mandatory. If you enjoy that anyway, all the better. If you prefer to invest your time in other things, a new purchase is easier to maintain.
Conclusion: Conversion is possible, but not always worthwhile
Converting a regular bicycle into an electric bike with a top speed of 25 km/h is not witchcraft. Depending on the provider or bike conversion kit, the installation can be done without a dealer’s prior knowledge and support. In addition, you can choose between different systems, and you do not have to do without a GPS tracker for modern theft protection.
However, this method is especially suitable if you own a high-quality bicycle that you have grown fond of and want to convert it into an e-bike in the long term. Otherwise, it might be better to take a look at affordable new e-bikes first. After all, the conversion is usually not that much cheaper and with a new model, you can be sure that all components complement each other for a good riding experience.
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