Bicycle Speed Booster Electric Kit: A How-To Guide

Installing an electric speed booster kit on your bicycle means transforming it into an e-bike, giving you pedal assistance and extra speed. This guide walks you through the process step-by-step, focusing on common kit types so you can do it yourself.

Key takeaways:

• Most DIY electric bike kits use either hub motors or mid-drive motors.
• Installation typically takes 3 to 6 hours with basic tools.
• Always check for frame clearance and component compatibility before buying a kit.
• Plug-and-play connectors simplify the wiring for most modern kits.

What kind of electric bike kit should you pick?

You'll generally choose between two main types of electric bike kits: hub motor kits and mid-drive motor kits. Hub motors are simpler to install because they replace one of your existing wheels. Mid-drive motors offer better performance and weight distribution but are more complex to fit into your bike's bottom bracket.

Here's a quick comparison:

For this guide, we'll cover the general steps applicable to both, highlighting differences where necessary. Most kits today come with a motor, battery, controller, display, and throttle or pedal assist sensor.

What tools will you need for the installation?

You'll need a basic set of bicycle tools. Don't worry, you probably have most of these already.

Here's a list:

• Allen wrench set
• Crescent wrench or adjustable spanner
• Screwdriver set (Phillips and flathead)
• Cable cutters for zip ties
• Zip ties for cable management
• Bike stand (optional, but very helpful)
• Tire levers and a pump (if replacing a wheel with a hub motor)
• Crank puller and bottom bracket tool (essential for mid-drive motor kits)
• Torque wrench (recommended for precise tightening, especially for mid-drive kits)

Make sure you have a clean, well-lit workspace. A small container for loose parts like bolts and washers is also a good idea.

Step 1: Prepare your bicycle and unbox the kit

First, clean your bike thoroughly. Dirt and grime can make the installation harder and potentially damage components. Remove any accessories that might get in the way, like water bottle cages or frame bags.

Next, carefully unbox your electric kit. Lay out all the components and cross-reference them with the kit's packing list. This ensures you have everything before you start. Check for any obvious damage to the motor, battery, or wiring. Read through your kit's specific instruction manual completely. Even if you've done this before, different kits have different nuances.

Step 2: Install the motor (hub or mid-drive)

This is the core of the conversion. The process differs significantly based on your motor type.

For Hub Motors:

1. Remove the existing wheel: Use your wrench to loosen the axle nuts on your front or rear wheel. Take off the wheel. If it's the rear wheel, you'll also need to remove the chain.
2. Transfer components (if necessary): If your hub motor kit didn't come with a tire and tube, transfer them from your old wheel using tire levers. For rear hub motors, you might need to transfer your freewheel or cassette. This often requires a special freewheel or cassette tool.
3. Install the new wheel: Carefully slide the hub motor wheel into the dropouts of your bike's frame. Make sure the motor's cable exits correctly and isn't pinched. Tighten the axle nuts firmly. Many kits specify a torque of around 30-40 Nm.
4. Reconnect the chain: If you removed the rear wheel, put the chain back on.

For Mid-Drive Motors:

1. Remove cranks and bottom bracket: This is the most involved part. You'll need a crank puller to remove your bike's crank arms. Then, use a bottom bracket tool to remove the existing bottom bracket. Keep all parts organized.
2. Mount the mid-drive motor: Slide the mid-drive motor into the bottom bracket shell. Align it according to your kit's instructions. Secure it with the provided mounting plates and bolts. Torque these bolts to the manufacturer's specifications, often around 15-25 Nm.
3. Install the chainring and cranks: Attach the new chainring that came with your kit to the motor. Then, re-install your bike's crank arms (or new ones if provided) onto the motor's spindle. Tighten the crank bolts securely.

Step 3: Mount the battery securely

The battery is usually the heaviest component, so secure mounting is crucial. Most kits come with a mounting plate that attaches to your bike's water bottle cage bosses.

1. Attach the mounting plate: Use the screws provided to attach the battery's mounting plate to your frame's water bottle cage mounts. If your bike doesn't have these, or you prefer another location, you might need alternative mounting solutions like frame bags or rear racks, which are usually sold separately.
2. Slide on the battery: Once the plate is secure, slide the battery onto the plate until it clicks into place. Most batteries have a lock and key mechanism; use it to secure the battery against theft and accidental dislodging.

Step 4: Install the controller, display, and sensors

These components are the brains and input for your e-bike.

1. Mount the display: Attach the display unit to your handlebars. Typically, a clamp and screw secure it. Position it so it's easy to see without obstructing your view or controls.
2. Install the throttle (if applicable): If your kit includes a thumb or twist throttle, install it next to your existing grip on the handlebars. Ensure it doesn't interfere with your brake levers or shifters.
3. Attach the pedal assist sensor (PAS): This sensor tells the motor when you're pedaling. It usually mounts near your bottom bracket. For mid-drive motors, it's often integrated. For hub motor kits, you might need to attach a magnetic disc to your crank arm and a sensor to your frame. Make sure the sensor and magnets are close enough to register movement, usually within 2-3 mm.
4. Mount the controller: The controller is often housed in a small box. It might attach to the frame, or sometimes it's integrated into the battery mount. Find a secure, out-of-the-way spot, often near the battery or motor.

Step 5: Connect all the wiring

Modern kits often use color-coded, plug-and-play connectors, which simplifies this step significantly.

1. Connect the motor cable: Plug the motor's main power cable into the corresponding port on the controller. These are usually robust, multi-pin connectors.
2. Connect the battery cable: Plug the battery's power cable into the controller. This is typically a thick, two-pin connector.
3. Connect the display and throttle/PAS: Plug in the cables from the display, throttle (if used), and pedal assist sensor into their respective ports on the controller. They are usually smaller, multi-pin connectors.
4. Manage cables: Use zip ties to neatly secure all cables to your bike's frame. Route them along existing cable paths where possible. Avoid loose cables that could snag on things or get caught in moving parts like the wheels or chain. Ensure cables have enough slack for turning the handlebars and for suspension movement if your bike has it.

Step 6: Perform initial checks and a test ride

Before hitting the road, do a thorough check.

1. Power up: Turn on the battery and then the display. Check if the display lights up and shows information.
2. Check motor function: With the rear wheel off the ground (if you have a rear hub motor), gently twist the throttle or spin the pedals to activate the motor. Listen for unusual noises.
3. Brake cut-off (if installed): If your kit included brake lever cut-off sensors, test them. The motor should immediately stop assisting when you pull a brake lever.
4. Pedal assist levels: Cycle through the pedal assist levels on your display to ensure they change correctly.
5. Tightness check: Double-check all bolts and connections. Make sure nothing is loose.
6. First ride: Start with a short, gentle ride in a safe area. Pay attention to how the motor engages and disengages. Test the brakes thoroughly. If anything feels off, stop and re-check your installation.

It's normal to make small adjustments after your first ride. You might need to re-route a cable or tighten a bolt a bit more. Take your time, and enjoy your newly electrified ride.