Why this happens
Under Indian rules, low-power, low-speed electric two-wheelers are exempt from registration only within limits on motor power and top speed, currently 250 W and 25 km/h, but check the latest notification and any approval requirement for kits before you buy. A complete, matched kit with its own BMS-equipped battery and charger keeps the conversion safe; mixing parts or raising power takes it outside the exemption.
What you need
Tools
- Bicycle tool set with hex keys and spanners
- Torque wrench
- Tyre levers and pump
- Crank puller and bottom bracket tool if the kit needs them
- Digital multimeter
- Cable ties and side cutters
Materials
- Complete pedal-assist conversion kit within legal limits: hub motor wheel, controller, pedal-assist sensor, brake levers with motor cut-off, display, wiring
- The kit's own sealed battery with built-in BMS and its matching charger
- Torque arm for the hub motor
- Spiral wrap or cable sleeving
- Grease for axle threads and bolts
Before you start
- Do not choose or set up a kit that exceeds the current legal motor power or assisted speed limits; doing so means the vehicle needs registration, insurance and a licence.
- Never disconnect the brake cut-off switches or set the controller to give assist without pedalling beyond what the rules allow.
- Use only the kit's sealed, BMS-equipped battery and its matching charger; never open the battery or build your own pack.
- Front fork dropouts on many bicycles are not designed for motor torque; always fit a torque arm and prefer a rear motor.
- Upgrade worn brakes before conversion; the bicycle will be heavier and faster on average.
Step by step
- 1
Check the law and the bicycle
Read the current notification for low-speed e-bikes and confirm the kit's motor power and assisted speed are within it, and whether the kit or conversion needs approval. Keep the kit's documents. Then inspect the bicycle: a straight, uncracked frame, steel or strong rear dropouts, good wheels and brakes. If the frame or brakes are poor, fix them first or choose another bicycle.
- 2
Fit the motor wheel and torque arm
A rear hub motor is usually the safer choice, because front forks are often not designed for motor torque. Remove the old wheel, move the tyre and cassette or freewheel as the kit instructs, and fit the motor wheel with the cable exiting as specified. Fit the torque arm so the axle cannot spin in the dropouts, and tighten axle nuts to the kit's torque value.
Tip: Check the motor cable cannot be pinched when the wheel is removed or the bicycle falls over.
- 3
Install the pedal-assist sensor
Fit the pedal-assist sensor at the crank as the kit describes, often a magnet disc behind the chainring and a sensor on the frame. Set the gap between magnet and sensor to the kit's specification. Pedal assist must only work while you pedal and must stop when you stop; this is part of what keeps the conversion a pedal-assist cycle.
- 4
Replace brake levers with cut-off levers
Fit the kit's brake levers, which contain switches that cut motor power when you brake. Reconnect brake cables and adjust them so the brakes bite firmly. Check each lever's switch with the multimeter's continuity test before connecting it to the controller. Never leave these switches disconnected; they stop the motor fighting the brakes.
- 5
Mount the controller and battery
Mount the battery on the kit's frame cradle or rack with its lock, keeping its weight low and central. Mount the controller where it gets airflow and is protected from water spray. Do not open the battery or adjust the controller's power or speed settings beyond the legal limits. Use only the kit's own charger for the kit's battery.
- 6
Route and connect the wiring
With the battery removed or switched off, connect the motor, sensor, brake levers, display and battery leads to the controller, matching connectors and colours as the kit's diagram shows. Route cables along the frame with cable ties, away from the wheels, chain, brake discs and moving steering. Leave enough slack for full steering lock. Protect cables with spiral wrap.
- 7
Set up and test with the wheel off the ground
Support the bicycle so the rear wheel spins freely. Fit the charged battery, switch on and check the display. Turn the crank by hand: the motor should start gently, and stop when you stop pedalling or pull either brake lever. Confirm the assisted speed limit in the display settings is within the legal limit and is not changed.
- 8
Test ride and recheck
Ride slowly in a safe, open place wearing a helmet. Test braking hard from low speed, assist cut-off on braking, and that assist fades out at the set limit. After the first rides, recheck axle nuts, torque arm, brake adjustment and cable ties. Inspect the dropouts regularly for any sign of the axle moving or cracking.
How to tell it worked
The bicycle gives smooth assist only while pedalling, cuts the motor instantly on either brake, stops assisting at the legal speed limit, and passes a recheck of all fasteners after the first rides.
Stop and call a technician if
- The axle moves in the dropouts, the torque arm loosens or the frame shows any crack.
- The battery or controller gets hot, smells of burning or the battery case is damaged.
- The motor runs without pedalling or does not cut off when you brake.
- You are unsure whether your kit or conversion meets the current rules; ask your transport office before riding on roads.
Questions
Can I fit a more powerful motor if I ride carefully?
Not and stay exempt from registration. Exceeding the low-speed limits means the vehicle must be registered and insured, and the rider needs a licence.
Can I use a battery from another kit or a cheaper charger?
Use only the kit's own battery and its matching charger. A mismatched battery or charger can overcharge cells or overload the controller and is a fire risk.
Is a front or rear hub motor better?
A rear motor is generally safer for conversions because rear dropouts usually handle torque better and traction is better. Always use a torque arm either way.