Bafang Mid Drive Kit: A Complete Buyer’s and Installation Guide

The dream of turning your favorite bicycle into a powerful, hill-crushing ebike is easier than ever. You don't need to pay the high price of a pre-built model. The Bafang mid drive kit is one of the most popular, powerful, and affordable solutions for any DIY e-bike project.

Unlike hub motors that power the wheel directly, a mid drive motor powers your bike's crank. This setup lets the motor use your bike's existing gears, giving you better climbing ability, balanced weight, and a more natural riding feel. This guide will walk you through every important step. We will cover picking the right model, making sure your bike works with it, the complete installation process, and setting up for your first exciting ride.

Why Choose a Bafang?

Picking a conversion kit is a big decision. You need to understand both the good points and the possible downsides. A Bafang mid drive kit is a top choice in the DIY community for several strong reasons, but you should also know what to expect.

Here are the main benefits:

• Power and Torque: For the price, the performance can't be beat. These kits are known for their ability to handle the steepest hills and carry heavy loads, offering from 100Nm to over 160Nm of torque depending on the model. This level of power changes your riding experience completely.
• Natural Ride Feel: The motor helps you at the crankset, which is the heart of your bicycle drivetrain. This lets you shift gears to keep the motor in its most efficient RPM range, just like you would with your own legs. This is one of the key advantages of a mid-drive system.
• Cost-Effectiveness: You can build an e-bike with a Bafang mid drive kit for much less than a pre-built e-bike that has a similar mid-drive motor from brands like Bosch or Shimano.
• Customization: Building your own e-bike gives you complete control. You can pick the exact battery size, display type, and other parts to create a machine perfectly made for your needs, whether for commuting, touring, or trail riding.

Here are some things to think about:

• More Drivetrain Wear: The high torque and power of a Bafang motor will put more stress on your chain, cassette, and chainring than you would see on a regular bike or a bike with a less powerful motor. You'll need to replace these parts more often.
• Installation Difficulty: Compared to a simpler hub motor kit, installing a Bafang mid drive kit needs more mechanical skill and a few special tools. It means removing your bike's bottom bracket and cranks.
• Cadence-Sensing PAS: Standard Bafang kits use a cadence-based pedal assist sensor (PAS). This system gives power when it senses that you are pedaling, acting like an on/off switch for a set power level. This can feel less natural than the more advanced torque sensors found on expensive e-bikes, which measure how hard you are pedaling and give matching assistance.

BBS02B vs. BBSHD

For most DIY builders, the choice comes down to two famous models: the Bafang BBS02B and the Bafang BBSHD. While Bafang also makes the frame-built "Ultra" motor, it needs a special frame and is not a universal conversion kit. For converting a standard bike, the BBS02B and BBSHD are the best options. Understanding their differences is key to picking the right motor for your build.

A direct comparison makes the decision much clearer:

For most riders, the Bafang BBS02B offers more than enough power for daily commuting and fun trail riding. It is a great, versatile motor that gives a thrilling boost without being too much. The Bafang BBSHD is the "bulletproof" choice. If your goal is to build an off-road beast, haul heavy cargo, or conquer the most extreme hills without breaking a sweat, the overbuilt construction and huge torque of the BBSHD make it the clear winner.

Pre-Purchase Compatibility Check

This is the most important section of this guide. Checking your bike's compatibility before you buy a Bafang mid drive kit will save you from frustration, unexpected costs, and the disappointment of a failed project. Don't skip these steps.

Measure Your Bottom Bracket (BB)
The bottom bracket is the round shell at the bottom of your bike frame where the crank arms spin. You need two measurements: width and internal diameter.

• Width: Use a ruler or calipers to measure the width of the shell, not including any parts that may be sticking out. Most standard bikes have a 68mm or 73mm BB width, which is perfect for standard Bafang kits. Fat bikes often have 100mm or 120mm BBs, which need a specific version of the BBSHD.
• Diameter: Most compatible bikes use a threaded English BB. The internal diameter should be around 33.5mm. If your bike has a press-fit bottom bracket (a smooth, non-threaded shell), you will need a special adapter to mount the Bafang motor.

Check Chainstay Clearance
The Bafang motor has a main housing that sits behind the bottom bracket. This housing can interfere with the bike's chainstays (the tubes running from the bottom bracket to the rear wheel). This is a very common point of incompatibility, especially on modern mountain bikes with complex frame shapes. To check, you can download a to-scale template of the motor from the seller's website, print it, cut it out, and hold it up to your bike's bottom bracket area to see if it fits without hitting the frame.

Confirm Battery Mounting Space
The best place to mount an e-bike battery is inside the main frame triangle on the down tube. This keeps the center of gravity low and balanced.

• Check for bottle cage mounts, as these are the standard mounting points for a battery cradle.
• Use a tape measure to check the available length and width inside your frame triangle. Compare this to the dimensions of the battery you plan to buy. Smaller frames or full-suspension designs may not have enough space for a large "shark" style battery, requiring you to consider a rear rack-mounted battery instead.

Identify Your Brake Type
The Bafang mid drive kit comes with new brake levers that have built-in motor cut-off sensors. When you pull a brake lever, it instantly cuts power to the motor. These included levers are designed for cable-operated brakes (like V-brakes or mechanical disc brakes). If your bike has hydraulic brakes, you cannot use these levers. You must buy separate, add-on hydraulic brake sensors that stick onto your existing levers or install inline with the hydraulic hose.

Step-by-Step Installation

With a compatible bike and the right kit, the installation is a rewarding process. We recommend setting aside a few hours and working carefully.

First, gather your tools.
* Essential Special Tools: Crank puller, bottom bracket tool (specific to your bike's BB).
* Standard Tools: A good set of metric Allen keys, socket/wrench set, screwdrivers, zip ties, and quality bicycle grease.

Preparation and Removal
Secure your bike in a repair stand for easier access. Begin by removing the pedals (remember the left pedal is reverse-threaded). Use the crank puller to remove both crank arms. Next, use the right bottom bracket tool to unthread and remove the entire bottom bracket cartridge from the frame. Thoroughly clean the inside of the now-empty bottom bracket shell.

Motor Installation
Carefully slide the Bafang motor's axle through the bottom bracket shell from the drive (chainring) side of the bike. Position the motor so it is angled upwards slightly, following the line of the down tube. It must not point down where it could strike obstacles. On the non-drive side, place the mounting bracket over the axle and secure it with the two provided lockrings. Use the special Bafang wrench to tighten these rings securely. This connection is what prevents the motor from rotating under its own torque.

Component Installation
Attach the chainring to the motor unit. Install the new crank arms that came with the kit onto the motor's axle and tighten them firmly. Mount the LCD display in the center of your handlebars and attach the control pad near your left grip for easy access. If you are using a throttle, mount it near your right grip. On the rear of the bike, attach the speed sensor to the chainstay and the small magnet to a spoke on the rear wheel, making sure they pass within a few millimeters of each other. Finally, mount the battery cradle to your down tube's bottle cage mounts.

Wiring and Cable Management
This is the final step. The Bafang wiring harness is designed to be plug-and-play. The connectors are color-coded and shaped differently to prevent mistakes. Connect the display, control pad, throttle, and brake sensors to the main harness. Connect the main power leads to the battery cradle. We highly recommend installing an optional gear shift sensor. This small device plugs into the harness and briefly cuts motor power when you shift gears, which greatly reduces wear on your chain and cassette. Once everything is connected, neatly route the cables along your frame, using zip ties to secure them and create a professional-looking, safe installation.

First Ride and Setup

Before you take off, a few final checks and adjustments will ensure a safe and enjoyable experience.

Basic Programming and Checks
Power on the system using the control pad. The display will light up. Go into the settings menu to configure basic parameters like your wheel size and preferred units (mph or kph). Setting the wheel size correctly is crucial for an accurate speedometer. While advanced programming is possible with a separate USB cable to fine-tune every power level, we strongly advise starting with the stock settings. Before riding, lift the rear wheel and test the system. Make sure the brake levers cut power to the motor. Test the pedal assist by turning the cranks and check that the throttle works as expected.

First Ride Tips
Your first ride is about getting used to the new feel of your bike.

• Start in a low gear and the lowest pedal assist level (PAS 1).
• Pedal gently to feel how the cadence sensor engages. There will be a slight delay before the power kicks in.
• Practice shifting gears. Try to ease off your pedaling pressure slightly just before you shift, especially if you did not install a gear sensor. This mimics how you would shift on a normal bike and is much gentler on your drivetrain.
• Get a feel for the power in each assist level before moving up. The jump in power can be surprising. Enjoy the new power and speed of your custom-built e-bike.

Mid-drive systems shine because they put power right where you need it — giving you better balance, smoother climbs, and more efficient use of every pedal stroke. The Leoguar mid drive eBike brings all those benefits in a ready-to-ride package, so you can skip the hassle of a DIY kit and enjoy pro-level performance from day one.

Frequently Asked Questions

1. Q: How long does it take to install a Bafang mid drive kit?
A: Installation typically takes 3-5 hours for someone with basic bike maintenance skills. If you're new to bike repair, plan for a full day and consider having a bike shop help with the more technical steps.

2. Q: Can I install a Bafang kit on any bike?
A: Not all bikes are compatible. You need to check your bottom bracket size (usually 68mm or 73mm), ensure adequate chainstay clearance, and have mounting space for the battery. Full suspension bikes and some modern carbon frames may not work.

3. Q: How much does a complete Bafang conversion cost?
A: A complete conversion typically costs $800-1500, including the motor kit ($400-700), battery ($300-600), and any additional parts needed. This is much less expensive than buying a comparable pre-built e-bike.

4. Q: What's the difference between the BBS02B and BBSHD motors?
A: The BBS02B offers 500-750W with about 120Nm of torque, perfect for commuting and moderate hills. The BBSHD provides 1000W with 160Nm of torque, designed for heavy cargo, steep hills, and more demanding use.

5. Q: How often will I need to replace drivetrain components?
A: With a Bafang motor, expect to replace your chain every 1000-2000 miles and your cassette/chainring every 2000-4000 miles, depending on usage. Installing a gear shift sensor and proper shifting technique can significantly extend component life.