Convert a Bike to an E-Bike: Overview and Steps

Yes, you can convert most ordinary bikes with a steel or aluminium frame. A kit with battery costs roughly 400 to 1,700 euros, depending on motor type and quality. Whether it works on your bike comes down to brakes, frame, hub spacing and drivetrain, and that is what we go through here, one step at a time.

Is it worth it?

A conversion is worth it if you have a bike you like, that fits you well, with a solid frame. It is not worth it if brakes, wheel and worn parts end up costing nearly as much as a used e-bike. A new e-bike costs about 2,500 euros on average (Upway). If your conversion, all in, heads that way, be honest with yourself: skip it and buy used.

How a conversion works

1. Record your bike. Note wheel size, hub spacing, brakes, gearing, bottom bracket and frame material.
2. Choose a motor type. Front, rear or mid-drive (see below and motor types compared).
3. Buy a kit. Check voltage, continuous rated power, sensor type and pedelec compliance.
4. Replace worn parts first. Chain, pads, tyres and brakes before the conversion, not after (GIGA).
5. Install. Motor, battery, sensors, display and brake levers with cut-off.
6. Route and test the cables. Connectors are usually the most common source of faults.
7. Set up and check. With Bafang controllers you can check the speed limit with a programming cable (netzwelt).

For a first install, plan on an afternoon up to a weekend, depending on motor type. The mid-drive is the most work.

Motor types in short

Details are in motor types compared. If you are torn between mid-drive and hub motor, see mid-drive or hub motor.

What your bike needs to offer

• Frame and fork: Steel and aluminium are suitable, carbon is not (GIGA). More under frame and weight.
• Hub spacing: At the rear, 135 mm is standard for most hub motors; at the front it is usually 100 mm. See hub spacing.
• Wheel size: The ETRTO number on the tyre counts, not the inch name. See wheel sizes.
• Brakes: More weight and speed push rim brakes to their limits. See brakes.
• Coaster brake: The most common deal-breaker. See coaster brake.
• Bottom bracket (mid-drive only): See measure your bottom bracket.

The battery

The battery decides range and weight. Capacity in Wh is volts times amp-hours, for example 36 V × 14 Ah = 504 Wh. Real-world range is often only about 70 percent of the manufacturer's figure (GIGA). As a rule of thumb, assume 8 to 15 Wh per kilometre. Positions, space needed and safety are covered under battery.

Costs

Prices without guarantee, as of November 2026. A fuller breakdown is under costs, the matching tools under tools.

Law: what is allowed

For your bike to stay legally a bicycle, it has to be a pedelec:

• Continuous rated power of at most 250 watts. Peak power can be higher, but many shops advertise exactly that peak. Look at the continuous rating.
• Assistance only while pedalling and only up to 25 km/h.
• A throttle is only allowed as a walk-assist up to 6 km/h, without pedalling.

Anything beyond that counts as a motor vehicle. Without a speed sensor a kit cannot hold 25 km/h (GIGA). More under pedelec law. This is not legal advice.

Budget tiers

Roughly three tiers (rules of thumb, no guarantee):

• Budget, about 400 to 600 euros: usually a cadence sensor and no-name cells. Check pedelec compliance closely and expect little support.
• Solid, about 600 to 1,000 euros: torque sensor, branded cells, designed as a pedelec, EU dealer. For most people this is the sensible range.
• Premium, about 1,000 to 1,800 euros: finely tuned torque sensor, warranty and EU replacement battery, manufacturer in the German-speaking region.

The feel differs a lot between a cadence sensor and a torque sensor: the first feels like being pushed, the second assists in proportion to your pedalling. More in the glossary.

Safety and upkeep afterwards

A converted bike is heavier and faster than before, and you notice it in the brakes, spokes and chain. After the first 100 kilometres, check spoke tension and bolts, especially with hub motors. Do not charge the battery unattended and inspect it after a crash. With a mid-drive, ease off pedalling when you shift so the chain does not suffer. These are experience-based values that Fabio is still checking.

When to leave it

• The frame or fork is carbon.
• The bike has a coaster brake and you want a rear hub motor.
• The bike is old, its parts are worn, and you would have to replace brakes, wheel and drivetrain.
• You do not want to wrench yourself and no workshop will take it on. Some workshops refuse conversions because they count as tampering with the manufacturer's product (Fahrrad XXL).
• You need the bike manufacturer's warranty. It usually lapses after a conversion (GIGA).

DIY or workshop?

With some workshop experience you can manage a front or rear motor conversion yourself. You need time, patience and the right tools, above all a torque wrench. A mid-drive adds special tools such as a crank puller, a bottom bracket tool and often a lockring spanner that is not always in the kit. The list is under tools.

If you are unsure, find a conversion-friendly workshop before you buy the kit. Ask specifically whether they accept kit conversions. That saves trouble if something sticks during lacing or setup. Hourly rates vary a lot by region, and we do not have firm figures yet.

The first kilometres

Take your first rides on a quiet, familiar route. Test whether the motor cuts out immediately when you brake, whether it tapers off smoothly at 25 km/h and whether anything rubs or wobbles. If the motor judders, the cause is often the cadence sensor or a connector. If the power cuts out, check the connectors for water first. Common problems helps with this.

Avoiding typical mistakes

Most problems come from cheap parts without pedelec compliance, a missing torque arm, mismatched voltages between battery and controller, or badly routed cables. An overview of causes and fixes is under common problems. The glossary explains unfamiliar terms.

How reliable is this?

Legal limits, the kit price range, frame material and warranty come from the sources named; rules of thumb on range, tools and extra costs and many compatibility details are experience or assumptions that Fabio is still checking.

Does a conversion fit your bike?