DIY Electric Mountain Bike Conversion: Step-by-Step Guide

DIY Electric Mountain Bike Conversion:

Want to experience electric mountain biking but don’t have the budget for a purpose-built e-bike? Converting your existing mountain bike to electric power is a fun project that saves money. This DIY eMTB conversion guide covers everything needed to electrify your manual MTB and hit the trails with power assist.

Key Takeaways – DIY eMTB Conversion

Is a DIY eMTB Conversion Worthwhile?

Electrifying a standard mountain bike has some compelling benefits:

• Saves money – Much less costly than buying a ready-made eMTB
• Customize components – Hand pick motor, battery and accessories
• Retain beloved bike – Breathe new life into old faithful steed
• Learn about e-bikes – Understand components and maintenance
• Fun project – Enjoy the build process and satisfaction

But also be realistic about the tradeoffs:

• Results won’t match integrated eMTB – Heavy, less balanced, reliability challenges
• Component compatibility headaches – Drivetrain, wheel, frame limitations
• Technical complexity – Electrical, programming and bike mechanics skills needed
• Voided warranties – Manufacturers won’t honor frame guarantees

Approach an eMTB conversion as a hobby project, not expecting a bike shop level outcome. Managing expectations will lead to more grins per mile!

DIY eMTB Conversion Component Overview

Transforming a standard mountain bike to electric power requires several new components:

Motor – Provides pedal assist power matched to your needs

Battery – Rechargeable lithium packs to energize the motor

Controller – Manages and modulates power from the battery to motor

Throttle – Lets you control assistance level on demand

Display – Shows speed, battery level, power mode and other info

Wiring – Connects electrical components neatly and securely

Parts selection depends on your budget, donor bike compatibility, power needs and technical capabilities. Let’s dive into the options…

Choosing a Motor for DIY eMTB Builds

The motor determines available power and torque. Two main options exist:

Hub Motors

• Contained inside the front or rear wheel
• Require no drivetrain modifications
• Less optimal weight distribution affects handling
• Provide less torque compared to mid-drives

Mid-Drive Motors

• Mounted centrally at the bottom bracket
• Transfer power through drivetrain for better traction
• Require adequate gearing and chain to handle torque
• Better balance by keeping weight central

For most DIY eMTB builds, a mid-drive motor is ideal since these can take advantage of the bike’s existing drivetrain and geometry. Look for kits including brackets for your specific bottom bracket type.

Consider a 500-750 watt unit to give sufficient trail assist without overwhelming the bike. Peak power should be governed to avoid smoking components when cresting 1500-2000 watts. Test your gearing first without assist to ensure it can handle the torque.

Selecting the Right Battery for DIY eMTBs

The battery capacity determines range. Look at:

• Voltage – Typically 36V, 48V or 52V. Higher voltage provides more power.
• Watt hours – 300Wh is light duty, 500Wh+ gives longer range.
• Battery chemistry – Lithium ion, lithium polymer, or lithium manganese. Each has pros and cons.
• Format – Frame or rack mounted hard case? Soft packs? Balance weight.
• Quality cells – Stick with reputable brands like Samsung, Panasonic, LG.

Consider 36V or 48V lithium ion batteries around 500-1000Wh capacity for a versatile blend of range, power and weight. Plan where you’ll mount the battery – downtubes, triangles, or rear racks are common.

Pay for quality battery components or risk destroying your expensive motor if electrical shorts occur. Don’t scrimp here.

eMTB Controller to Manage Power Delivery

The controller takes energy from the battery and feeds it to the motor in a managed way. Consider:

• Power curves – How quickly does motor rev and torque get delivered based on input?
• Programmability – Can you alter performance via a computer connection?
• Controller max rating – Motor peak watts shouldn’t exceed this.
• Voltage range – Compatible with your battery spec?
• Settings – Speed limiters, torque caps, thermal throttling?

Test different assist curve programming if adjustable to see what feels most natural depending on your motor. 20-30 amp controllers balance cost and sufficient output for most eMTB builds.

Choosing Display, Throttle and Control Options

These components allow controlling and monitoring the e-bike system:

Display

• Simple LED vs full color touchscreen
• Displays speed, battery level, assist mode etc
• Connects to controller via CAN bus or analogue
• Waterproofing rating

Throttle

• Finger lever or twist grip
• Proportional power or basic on/off
• Thumb triggers an option but less ergonomic
• Consider adding even on pedal-assist only eMTBs

Brake levers

• Motor power cutoff switches for safety
• Integrate controls into brake clamp area

Test different display mount positions and control configurations when possible. Hide wires for a clean cockpit.

Wiring Basics for DIY eMTBs

Connecting components electrically seems straightforward but do it right for reliability:

• Use correct gauge wire for the amp load
• Follow spec’d fuse requirements
• Strain relieve and protect all connections
• Avoid running wires through moving parts
• Label wires clearly for future maintenance
• Weatherproof outdoor connections
• Loom and zip ties for neatness
• Check clearance around moving parts

Take time routing and finishing wiring or vibrations and water will eventually ruin your hard work. Do it to e-bike shop standards.

Component Compatibility for DIY eMTB Conversions

Not all components play nicely together. Check:

Frames – Measure clearance for motors, batteries and wiring. Suspension frames complicate builds.

Brakes – Disc brakes strongly advised. If swapping wheels, check rotor mount compatibility.

Drivetrain – Ensure your gearing can handle motor torque. Expect more wear and maintenance.

Tires – Fatter eMTB tires may not fit converted wheels or frames. Check clearances.

Rims – Higher spoke count wheels handle torque better. Build up hand built wheels specifically for the motor power.

eMTB weight – Frame, wheels, etc. must handle potentially >50 lb total bike weight with components.

Get professional help fabricating adapters, mounts, or parts to ensure reliable component integration. Don’t overload incompatible donor bike parts.

Programming Tips for DIY eMTB Builds

If using a programmable controller, you can fine tune the motor feel:

• Spin bike up on stand for testing without needing to ride
• Limit power bands to avoid sudden peaks
• Tune torque curve for smoothness at low speeds
• Set gradual acceleration from start
• Add crawl mode for precise technical riding
• Set top speed based on capability and trails
• Adjust regen mode strength for light trailing braking
• Update settings regularly as components wear in

Take time to properly set up your controller programming. This personalization maximizes performance and reliability. The tuning is part of the DIY fun!

Safety Checklist Before Riding a DIY eMTB

Converting a bike to electric power introduces risks if not done carefully. Always:

• Use a helmet and safety gear – Low speed crashes still injure
• Check alignments – Spin wheels to ensure no rubs
• Confirm component mounts are tight – Vibrations can loosen fasteners over time
• Inspect wiring – Look for any shorts risk from housing wearing
• Torque fasteners to spec – Overtightening can damage parts
• Shake bike rigorously – Verify nothing contacts moving parts
• Actual ride testing – Start on mellow terrain and low power
• Consider insurance – Cover liability and components

Don’t jump straight to high speeds or technical trails until you’ve validated stability. Pay a bike shop to inspect if wanting extra peace of mind. Safety first!

Legal Considerations for DIY eMTB Conversions

Building your own e-bike introduces regulatory complications:

• Motor power limits – Follow local electric bike laws on motor wattages
• Controller programming – Any settings exceeding legal specs can cause issues
• Insurance coverage – Some policies exclude DIY e-bikes or modifications

Review all local laws thoroughly. Seek liability insurance given the increased risks. And don’t modify any settings allowing your e-bike to exceed legal speeds. Keep it class 1 compliant.

Cost Estimate for DIY eMTB Conversions

Component costs add up for high quality parts. Budget approximately:

• Motor: $250-$1000+
• Battery: $300-$1000
• Controller: $100-$300
• Display: $50-$200
• Throttle: $50-$100
• Wiring parts and tools: $100-$300
• Extras like fenders or racks: $100-$500

Total expenses commonly range $1000 to $4000+ for DIY eMTB builds depending on power system, battery range, and accessories desired. Still far cheaper than buying complete production e-bikes. Take time sourcing deals on parts.

Key Takeaways for DIY eMTB Conversions

• Approach as a hobby project, not expecting professional grade results
• Mid-drive motors optimized for mountain biking integration
• 500Wh+ batteries provide ample range for most
• Test component compatibility and plan wiring carefully
• Programming allows customizing power delivery
• Inspect thoroughly and start slow to validate stability
• Quality parts and smart assembly improves results
• Understand legal requirements before riding your creation

Converting a standard mountain bike to electric can be extremely rewarding. Take your time, do it right, choose compatible quality components, and enjoy your custom e-bike masterpiece on trails less pedaled!

Frequently Asked Questions on DIY eMTB Conversions

Can any mountain bike be converted to electric?

Not always easily. Full suspension frames complicate builds. Limited tire or drivetrain clearance can become issues. Hardtails work best for DIY.

Is a mid-drive or hub motor better for conversions?

Mid-drives integrate with gearing better for technical trails. But hub motors are simpler to install. Most DIY builders prefer mid-drives.

What tools do I need for an eMTB conversion?

Basic bike mechanic tools plus crimpers, soldering equipment and voltmeter. An optional bike stand tremendously helps the build and programming process.

Can I charge with a normal wall charger or do I need a special e-bike charger?

Only use chargers designed explicitly for the voltage and chemistry of your e-bike battery. Never try charging with a standard wall charger – fire risk!

If I’m technically inclined, is a DIY eMTB worthwhile?

If you enjoy tinkering, learn fast, and are ready to problem solve issues, it can be very rewarding. But know it requires specialized skills. Professional help is recommended if unfamiliar with electrical and bike mechanics.

Conclusion

Converting a standard mountain bike to electric can net huge cost savings compared to buying a pre-built eMTB. But it requires technical skills, research and quality components to create a safe and reliable machine. Take your time with the motor, battery and electrical install. And don’t forget programming tuning to maximize performance. Done properly, you can enjoy trails for less exertion with your customized electric mountain bike and learn tons in the process. The power and satisfaction of riding your unique eMTB creation makes the effort all worthwhile.