How do you convert a classic bike into an electric bike?
Electric bikes are now an integral part of the urban landscape. But what if you want to keep your trusty city or racing bike, while enjoying electric assistance? It's possible, thanks to a conversion kit. In this article, find out how it works, what technical choices you need to make, and when a refurbished electric bike from Upway is the wisest option.
Written by: Hanna Stevens | October 30, 2025 | Reading time: 6 minutes
More about the author: Hanna Stevens
Hanna is an avid cyclist who loves exploring new routes and sharing her experiences to inspire others to get on their bikes more often.
Key findings
- Transforming a classic bike into an e-bike is entirely possible with the right components.
- Choose CE and UN38.3-certified equipment and ensure frame compatibility.
- For added security and warranty, a refurbished Upway bike is a reliable alternative.
Why convert your bike into an electric bike?
The main reason is cost: a good conversion kit costs between €350 and €1,200, while a new electric bike often costs twice as much. It's also a sustainable choice: you reuse the frame, wheels and components that are still in good condition.
A bike is suitable if :
- the frame is sufficiently rigid (avoid cracked aluminum or rusty steel),
- the fork accepts an axle of at least 9 mm,
- powerful brakes (disc or V-brake),
- and the electrical system can be installed safely (cables fixed, fuses fitted).
What does it take to convert a bike into an e-bike?
An electric bike is based on five main components. Their effectiveness depends on how well they are integrated.
| Component | Function | Suggested price (€) | Technical consulting |
|---|---|---|---|
| Engine | Transforms electrical energy into mechanical power | 250-600 | Check axle width (100 mm front, 135 mm rear) |
| Battery (36 V, 360-500 Wh) | Stores energy | 250-500 | Use 18650 Li-ion cells with integrated BMS |
| Controller & display | Manages power and assistance | 50-150 | Check that the controller supports a peak ≥ 15 A |
| Sensors | Measure cadence or pedaling force | 30-80 | Torque sensor for a more natural feel |
| Wiring | Connect all components | 20-50 | Choose IP65 waterproof connectors |
Energy consumption: 7-10 Wh/km in urban use. A 500 Wh battery therefore offers a range of 50 to 70 km (source: Bafang, 2024).
Types of conversion kits
The motor drives the front wheel directly.
Advantage: simple assembly, good balance if the battery is at the rear.
Disadvantage: reduced traction on wet roads; risk of slippage at high torque (> 40 Nm).
Yield: approx. 75-80%.
More natural in use, power comes through the chain.
Advantages: better traction, quiet operation.
Disadvantage: more complex installation with derailleur or thru axle.
Yield: 80-85%.
Tip: use reinforced spokes (2.3 mm).
Disadvantage: more complex installation with derailleur or thru axle.
Yield: 80-85%.
Tip: use reinforced spokes (2.3 mm).
The most powerful: it is placed on the crankset and uses the bike's transmission.
Advantages: high efficiency (up to 90%), optimal balance.
Disadvantage: more complex assembly, increased chain wear.
Torque: 60-85 Nm (Bafang M400: 80 Nm; Pendix eDrive: 65 Nm).
| Motor type | Rated power | Torque (Nm) | Weight (kg) | Yield (%) | Price (€) |
|---|---|---|---|---|---|
| Front wheel | 250 W | 30-40 | 3-4 | 75-80 | 350-600 |
| Rear wheel | 250 W | 40-60 | 4-5 | 80-85 | 500-800 |
| Central engine | 250 W | 60-85 | 4-6 | 85-90 | 800-1500 |
(Sources: Pendix.de and Bafang.com, 2024)
Conversion steps
- Frame check: Check mounting widths: 100 mm front, 135 mm rear.
- Measure bottom bracket: BSA 68 mm standard for central motor.
- Motor installation: Mount the wheel or crankset using a torque wrench (40-50 Nm).
- Battery mounting: Best stability: in the frame. Use tight M5 screws.
- Mounting the controller and sensors: Install a pedaling sensor (PAS) or a torque sensor.
- Connection and test: Observe polarity; measure 36 V DC with multimeter.
- Calibration and test: Check progressive assistance and motor cut-off during braking.
Safety tip: use timed 30 A fuses and check insulation after rain.
Battery and maintenance
The kits use 18650 Li-ion cells (240 Wh/kg). A 36 V / 13 Ah battery (≈ 468 Wh) offers around 65 km of range.
Best practices :
- Charge to 80-90% for longer life.
- Avoid discharges < 20%.
- Store at 15-20°C.
- Capacity loss: ± 2%/month in storage.
- After 500-1,000 cycles, capacity drops to around 80%.
Cost of conversion
| Kit type | Price (€) | Range (km) | Service life (years) |
|---|---|---|---|
| Front wheel | 350-700 | 40-60 | 3-4 |
| Rear wheel | 500-900 | 50-80 | 4-5 |
| Central engine | 900-1500 | 70-100 | 5-6 |
Additional costs :
- Tools: ± € 50
- Professional installation: ± €150
- Battery replacement (3-5 years): ± €300
A refurbished electric bike from Upway starts at around €1,000, with a one-year warranty - a price comparable to DIY, without the risks.
Test results
On three kits (Bafang M400, Swytch Front, Pendix eDrive300):
- Efficiency: central engine 91%, front 77%.
- Torque: Bafang measured at 78 Nm, within specification.
- Noise : Quietest Pendix (41 dB).
- Temperature: controller at 62°C uphill, within the norm.
- Observation: -20% range with headwind and under-inflated tires .
For whom is it (or isn't it) advisable?
Less suitable for :
- fragile or thin aluminum frames,
- people with no knowledge of electricity,
- bikes still under manufacturer's warranty.
Recommended for :
- DIY enthusiasts,
- sturdy city or touring bikes,
- users concerned with ecology and personalization.
Alternative: Upway's refurbished electric bike
At Upway, used bicycles are fully new according to a strict protocol:
- over 40 checkpoints (engine, electronics, frame),
- batteries tested (> 80% capacity),
- software updates and brake checks,
- one-year warranty on motor, battery and frame.
A durable, reliable, ready-to-run solution.
Conversion or refurbished : who wins?
| Aspect | Conversion | refurbished Upway |
|---|---|---|
| Price | 500-1 200 € | From €1,000 |
| Warranty | Limited / none | 1 year |
| Time | 4-6 h installation | Ready to use |
| Security | Check for yourself | Professionally tested |
| Battery | Varies by brand | CE & UN38.3 certified |
| Durability | Good (reuse) | Excellent (overhauled parts) |
Conclusion: transforming your bike is an instructive and economical project, but it requires technical expertise. AnUpway refurbished bike offers a similar price, with the peace of mind of a full warranty and inspection.
Next steps
- Check the dimensions of your frame and axles.
- Calculate your energy requirement (Wh/km).
- Compare reliable brands (Bafang, Pendix, Swytch).
- Or explore reconditioned electric bikes on Upway.fr or Upway.be.
FAQ
Can all bikes be converted?
No, only sturdy frames with good brakes.
What is the average cost?
Between €500 and €1,200, depending on the type of motor and battery.
How long does installation take?
About 3 to 6 hours for an experienced DIYer.
Is it legal in Belgium and the Netherlands?
Yes, if power ≤ 250 W and speed ≤ 25 km/h.
Can I replace the battery myself?
Yes, but always with a CE-certified battery.