Step-by-Step Guide to Install Rear Electric Bike Wheel
Installing a rear electric bike wheel from a conversion kit takes about two hours with basic tools. Success comes down to three things: matching the dropout width before you buy, using a torque arm to handle the motor’s torque, and routing wires so nothing gets pinched between the axle and the frame. This guide walks you through every step and flags the spots where things commonly go sideways.
What You’ll Need: Tools and a Compatible Kit
Gather these tools before you start:
- Cassette lockring tool (or freewheel remover) and a chain whip if you need to transfer your cassette
- 15 mm pedal wrench or adjustable wrench for the axle nuts
- Torque wrench capable of 25–35 ft·lb
- Zip ties and electrical tape for wire management
- Drill (if your controller needs a mounting bracket)
- Hex keys or Allen wrenches for brake caliper removal (if needed)
You also need to confirm your bike’s rear dropout width – typically 135 mm for standard mountain or hybrid frames, or 175 mm for fat-tire bikes – and your brake type (disc or rim). The conversion wheel must match both measurements, or you’ll end up with a loose fit or misaligned brakes.
The table below compares a popular rear-wheel conversion kit with two other e-bike products you might encounter in search results. The Powallon BAFANG G062 kit is the most direct fit for a fat-tire rear conversion.
| Product | Price | Brand | Rating | Feature 1 | Feature 2 | Feature 3 | Best For | |
|---|---|---|---|---|---|---|---|---|
| Rear Wheel E-Bike Conversion Kit 20 x 4 Fat Tire \ | BAFANG G062 48V 750W, PAS & Throttle, DZ40 Mini Display, Compatible with Cassette Sprocket (175mm Dropout)</a> | Check seller | Powallon | Not listed | 750W geared motor, 48V | Fat-tire compatible (20×4) | Cassette sprocket, 175 mm dropout | Rear-wheel conversion on fat-bikes |
| Electra Stubby Men’s Cruiser Fender Set (Black) | Check seller | ELECTRA | Not listed | Fits Electra cruiser models | Black plastic fenders | Front + rear | Appearance and mud protection | |
| EMOJO Electric Tricycle for Adults, 20 * 4.0 Inch Fat Tire Caddy Pro Trike, 500W 48V 7 Speed Hybrid 3 Wheel Bicycle with Hydraulic Brake, Oversize Rear Cargo and Front Basket (Grey Caddy Pro) | Check seller | EMOJO | Not listed | 500W motor, 48V | 20×4 fat tires | Hydraulic brake, cargo basket | Complete trike, not a conversion wheel |
Top Pick: Rear Wheel E-Bike Conversion Kit 20 x 4 Fat Tire \| BAFANG G062 48V 750W, PAS & Throttle, DZ40 Mini Display, Compatible with Cassette Sprocket (175mm Dropout) – this kit covers the most common rear-wheel conversion format (cassette compatible, fat tires, 175 mm dropouts) with enough torque for hills and cargo. For other wheel sizes or standard 135 mm dropouts, look for a kit that matches your frame measurements exactly.
Step 1: Prepare the Bike and Remove the Old Wheel
1. Disconnect all power – if the bike is already electric, remove the battery and disconnect any wiring from the old motor. For a standard bike, just confirm no battery is connected.
2. Secure the bike – use a work stand, or flip it upside down with padding under the saddle and handlebars to protect the frame.
3. Shift the chain to the smallest rear cog (or remove the chain entirely if you plan to work on the rear triangle). This keeps the chain slack and makes wheel removal easier.
4. Disconnect the brakes – for rim brakes, unhook the cable; for disc brakes, you may need to remove the caliper (two hex bolts) to slide the wheel out, but often you can just deflate the tire slightly. Consult your brake manual.
5. Loosen the axle nuts – use a 15 mm wrench on both sides, then remove the nuts and washers. Keep the washers in order; they often have a specific orientation.
6. Pull the old wheel out – wiggle it free from the dropouts. If the cassette or freewheel stays on the old wheel, set it aside for transfer.
Step 2: Transfer Your Cassette or Freewheel to the New Motor Wheel
Most conversion kits arrive with either a freewheel or a cassette body pre-installed. If yours already has a cassette, skip to Step 3. If you need to move your existing gears:
- For a cassette: Use a chain whip and lockring tool. Thread the lockring tool into the lockring, hold the chain whip on the largest cog to prevent rotation, and turn the lockring counterclockwise. Remove the cassette, then slide it onto the motor wheel’s freehub body. Tighten the lockring to 40 N·m (≈30 ft·lb) – check the torque spec in your kit manual.
- For a freewheel: Use a freewheel remover that fits the splines. Hold the remover with a large wrench and turn counterclockwise. Install the freewheel onto the motor hub by hand-threading clockwise, then tighten with the same tool.
If the new motor wheel uses a different freehub standard (e.g., HG vs. Microspline), the cassette won’t fit. Verify compatibility when you order the kit.
Step 3: Install Torque Arms
A torque arm is mandatory for any rear hub motor over 250W. The motor’s torque can spin the axle inside the dropout, damaging the frame and causing a crash. Most kits include at least one torque arm; buy a second if your frame has horizontal dropouts.
1. Slide the torque arm over the axle on the drive side (the side with the gears). The arm’s tab should rest against the frame’s dropout or a chainstay eyelet.
2. Tighten the arm’s clamp bolt (usually a hex screw) until it’s snug, but don’t fully torque it yet – you’ll adjust after the wheel is seated.
3. If using a second arm, repeat on the non-drive side. Some frames require zip-tying the arm to the chainstay. Never let the arm touch the spokes.
Step 4: Mount the Motor Wheel in the Dropouts
1. Place the motor wheel into the dropouts, making sure the axle flats align with the dropout slots. The torque arm tab should settle into the dropout’s notch.
2. Add the washers in the correct order: usually a flat washer, then a spring washer, then the axle nut. Check your kit’s diagram – reversing them can loosen over time.
3. Hand-tighten both axle nuts, then use a torque wrench to tighten to 25–35 ft·lb (or the value in your manual). Alternate between sides so the wheel stays centered.
4. Spin the wheel: it should rotate freely without rubbing the frame or the brake rotor. If it rubs, loosen the nuts, adjust the wheel position, and retighten.
Step 5: Install the Controller and Route All Wiring
The controller is the brains of the system. It’s often a black box that mounts to the bottle-cage bosses or inside the frame triangle.
- Mount the controller: Use the included bracket or zip ties. Keep it elevated off the ground and away from moving parts. A common spot is under the downtube.
- Route the motor cable: Feed the cable from the axle along the chainstay toward the controller. Leave a little slack near the axle so wheel movement doesn’t tug the connector. Secure with zip ties every 6–8 inches.
- Install the pedal-assist sensor (PAS): Most kits include a disc with magnets that mounts behind the bottom-bracket. Follow the kit’s spacing instructions – the gap between the sensor and magnet should be about 1/8 inch.
- Install the throttle and brake sensors: Thread the throttle cable along the handlebar and down the down tube. If your kit includes brake levers with cut-off switches, replace your existing levers. Route all cables neatly and zip-tie them together.
- Avoid pinching: Never run wires between the axle and the dropout – that’s where the torque arm lives. Pinched wires short out and can damage the motor controller.
Step 6: Connect the Battery and Test Operation
1. Connect the controller to the battery using the supplied power leads. If your battery is a frame-mounted bottle type, slide it into the cradle and lock it.
2. Turn on the display or ignition. The display should light up and show battery voltage.
3. Test the throttle: spin the rear wheel off the ground (use a stand or flip the bike). Gently twist the throttle – the wheel should spin smoothly. Listen for grinding noises.
4. Test pedal assist: rotate the cranks; the motor should engage within half a crank rotation. If it doesn’t, check the PAS magnet alignment.
5. Test the brake sensors: squeeze each brake lever; the motor should cut out immediately.
If anything fails, double-check every connector. The most common error is a loose wiring harness or a reversed throttle connection.
Step 7: Adjust Brakes and Perform Final Safety Check
- Disc brakes: After installing the motor wheel, the rotor may rub against the caliper. Loosen the two caliper mounting bolts, squeeze the brake lever firmly, and retighten the bolts while holding pressure. This centers the caliper.
- Rim brakes: Adjust the brake pads to clear the wider motor wheel if needed. Some conversion wheels have a larger rim width.
- Torque arm check: Re-tighten the torque arm clamp bolt to the manufacturer’s spec (often 8–10 ft·lb) once the wheel is fully seated.
- Wire management: Make sure no wires can catch on the chain, spokes, or frame. Use extra zip ties to bundle any loose loops.
Where People Get Stuck
- Torque arm orientation: If the arm’s tab
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Ryan Williams has spent over 8 years testing, repairing, and writing about electric bikes. He has personally ridden and reviewed 150+ e-bike models from brands like Lectric, Aventon, Rad Power, Super73, and dozens more.
Before founding EBIKE Delight, Ryan worked as a bicycle mechanic for 5 years at independent bike shops across California, where he specialized in e-bike conversions and electrical system diagnostics. He holds a Certificate in Electric Vehicle Technology from the Light Electric Vehicle Association (LEVA).
Ryan’s work has been cited by Electric Bike Report, Electrek, and BikeRumor. When he is not testing the latest e-bike on California backroads, he is in his workshop tearing down batteries and controllers to understand what makes them tick — and what makes them fail.
Areas of Expertise
E-bike performance testing and real-world range verificationBattery diagnostics, charging best practices, and safetyBrand comparisons: Lectric, Aventon, Rad Power, Super73, and moreError code troubleshooting across major e-bike systemsE-bike laws, registration, and compliance by state
Ryan believes every rider deserves honest, hands-on information — not marketing hype.