Electric Mountain Bike Motors: An Overview of Leading Systems

Electric Mountain Bike Motors: An Overview of Leading Systems

 

 

Key Takeaways
  • Mid-drive motors like Bosch, Shimano and Brose dominate eMTB applications.
  • Motors are tuned to match specific bike frames and riding styles.
  • Power output ranges from 250W on small motors up to 750W on performance models.
  • Torque sensing and cadence sensors determine power delivery.
  • Ideal motor depends on terrain, bike type, budget, and priorities.

 

Electric mountain bikes motors (eMTBs) utilize unique motor systems designed specifically for off-road riding. Selecting the ideal eMTB motor depends on your budget, bike style, riding terrain, and priorities.

In this guide, we’ll compare leading options from Bosch, Shimano, Yamaha, Brose, Specialized, Fazua, and more to highlight how manufacturers integrate motors to match intended eMTB applications.

Overview of eMTB Motor Types

The two primary types of eMTB motors include:

Mid-Drive Motors: Integrated into the bike’s bottom bracket area and transfer power through the drivetrain to the rear wheel. This provides a natural riding feel and optimal traction. But mid-drives do add complexity.

Hub Drive Motors: Contained sealed within the hub of the front or rear wheel. Direct drive hub motors are simple and weatherproof but can affect handling.

Nearly all performance-focused eMTBs today use mid-drive motor systems. But budget eMTBs sometimes opt for hub drives.

Within these locations, motors use different combinations of power, torque, cadence sensing, and control software to produce the desired assist characteristics.

Key eMTB Motor Brands

These are the most common eMTB-specific motor systems seen on modern electric mountain bikes:

Bosch

The German engineering specialists at Bosch produce the gold standard eMTB mid-drive motors like the Performance Line CX. Bosch focuses on refined, reliable, quiet power delivery.

Shimano

Also stemming from extensive drivetrain expertise, Shimano Steps e-bike motors feature intuitive power matched to cadence. Available in mid-drive or hub drive formats.

Brose

Known for their compact, powerful motors, Brose offers mid-mounted motors like the potent S-Mag tuned for serious eMTB performance.

Yamaha

With a focus on all-around natural ride dynamics, Yamaha’s PW-X mid-drive motors deliver smooth, seamless assist great for long days on the trail.

Specialized

Specialized Turbo e-bikes integrate custom mid-drive motors like the SL 1.1 designed in harmony with their frame kinematics and ride feel.

Fazua

At the forefront of lightweight, removable eMTB motor systems, Fazua produces the Evation mid-drive focused on simplicity and reliability.

Giant

Giant produces their own SyncDrive motors which integrate tightly with Giant’s renowned Maestro suspension platform for optimal handling.

In addition, some companies like Trek work closely with external motor suppliers like Bosch to tightly integrate their systems into frame designs.

Factors That Vary Among eMTB Motors

While all providing electric pedal assist, eMTB motors differ across these key attributes:

Power Output

Motor wattage determines torque and top speeds. Most eMTB motors range from 250W up to 750W max power. Lower output favors minimal added weight, while more output improves climbing traction.

Torque Delivery

Optimizing the torque curve for traction without too abrupt power delivery allows a natural, progressive assist. Cadence and torque sensors help achieve this.

Assist Responsiveness

Responsiveness refers to how quickly power delivery ramps up when pedaling input is detected. Quicker engagement can feel more jumpy.

Custom Tuning

The best systems are programmed specifically around a bike frame’s geometry, suspension design, component spec and intended handling.

Noise Level

Mid-drives require more noise isolation and damping to achieve whisper-quiet operation. Hub motors can buzz at times.

Weight Distribution

Centralized mid-drive weight aids handling, especially over rough terrain. Heavier hub motors alter weight balance.

Bosch eMTB Motor Systems

The German engineering experts at Bosch have defined the mid-drive e-bike motor standard. With continual refinement, their systems provide reliable torque with minimal noise:

Performance Line CX – Flagship mid-drive model makes up to 75 Nm of torque for technical trail riding. 4 assist modes.

Performance Line Speed – Models focused more on smooth speed offer great touring range with 20 mph top speed.

Performance Line – The standard well-rounded mid-drive option for regular MTB use.

Active Line – Lower torque compact mid-drive range for less aggressive eMTB styles.

Active Line Plus – Enhanced version of Active Line with greater torque and faster assist pickup.

Cargo Line – Heavy duty mid-drive designed for the demands of electric cargo and utility bikes.

Bosch motors integrate seamlessly into a wide range of reputable eMTB brands like Trek, Cannondale, Scott, and more. Their refined assist provides riders added capability without altering the essential mountain bike experience.

Shimano Steps eMTB Motor Systems

Shimano uses their extensive electronic and mechanical drivetrain expertise to produce highly functional eMTB motor systems:

Steps E8000 – Flagship mid-drive unit makes 70 Nm torque for aggressive trail performance. Smooth power delivery.

Steps E7000 – Lighter mid-drive balances weight and power well for cross country terrain.

Steps E6100 – Durable yet economical mid-drive optimized for value bikes.

Steps DU-E6100/E5000 – Reliable hub drive options mated with modern wide-range drivetrains.

Shimano builds their Steps e-bike systems using proven mountain bike drivetrain and brake components for seamless integration. With harmonic power delivery, Shimano motors almost disappear beneath a natural ride feel.

Yamaha eMTB Motor Systems

Known for power sports vehicles, Yamaha also produces refined mid-drive eBike motors like the PW-X:

PW-X – Compact mid-drive unit provides 70 Nm torque through smooth, seamless application. Tuned for optimal handling response.

PW-X2 – The enhanced version of PW-X adds 10 Nm more peak torque output.

PW-ST – Yamaha’s dedicated street eBike motor providing high efficiency commuting assist.

PW-TE – Yamaha’s ultra-compact mid-drive range provides basic assist with minimal weight addition.

Yamaha PW-X focuses on all-around electric power delivery across varied terrain. With rhythmic application and fine-tuned control software, Yamaha minimizes any unnatural riding dynamics from the pedal assist.

Specialized Turbo eMTB Motor Systems

Specialized optimizes performance by engineering their own proprietary mid-drive motors:

SL 1.1 – Custom lightweight motor provides 35 Nm torque matched precisely to Specialized’s frame kinematics.

SL 1.2 – The pinnacle Specialized motor boosting torque to 35 Nm and optimizing for the latest frames.

Brose 2.2 – Highest torque motor option at 90 Nm for Specialized’s downhill eMTB models.

By designing motors around their suspension platform and frames, Specialized achieves an incredibly natural, integrated eMTB feel. Smooth engagement comes on precisely when the rider’s output kicks in.

Brose eMTB Motor Systems

Renowned for their compact yet powerful eBike motors, Brose offers both mid-drive and hub drive systems for eMTBs:

S-Mag – High torque mid-drive motor making 90 Nm to conquer very rugged terrain.

T-Mag – Slimmer motor profile with 75 Nm still capable of aggressive trail performance.

Drive S-Mag – One of few dedicated eMTB hub drive motors, making 90 Nm torque. Sealed within rear wheel.

Brose uses intelligent electronics to apply power based on torque input for a very natural feel. Designed compactly, Brose motors center weight well on the bike.

Fazua Evation eMTB Motor System

The lightweight, removable Fazua Evation system takes a unique approach:

Evation – Compact mid-mounted motor and battery pack can detach to shed 7.7 lbs for light trail riding feel. 60 Nm torque provides capable assist when motor engaged.

By focusing on minimalism, simplicity, quick battery swaps, and light weight, Fazua has created an eMTB motor system optimal for versatility. The power hides almost invisibly when not needed.

Giant SyncDrive eMTB Motors

Giant is another major bike brand developing their own proprietary motors:

SyncDrive Pro (80Nm)**/**Life (60Nm) – Potent mid-drive motors mated to Giant’s Maestro suspension for optimal power delivery and handling.

SyncDrive motors allow Giant to leverage digital integration between frame, motor, and battery for an eBike experience fine-tuned to their acclaimed ride characteristics.

Hub Drive vs Mid-Drive eMTB Motors Compared

While less common on performance eMTBs, hub drive motors still suit some riders:

Hub Drive Advantages

  • Simpler, self-contained system
  • Quieter operation
  • Protects motor from weather

Hub Drive Disadvantages

  • Adds significant wheel weight
  • Harms handling and balance
  • Provides jerky power delivery

Mid-Drive Advantages

  • Natural power delivery through transmission
  • Centralized weight distribution
  • Maintains bike geometry

Mid-Drive Disadvantages

  • More complex integration
  • Exposed motor is vulnerable
  • Stress on drivetrain components

Overall, mid-drives provide a superior eMTB experience which is why nearly all off-road models now use them rather than hub drives. But budget eMTB shoppers can still get quality hub motors.

Most Important eMTB Motor Features

For top eMTB performance, the motor system should provide:

  • Enough power and torque for intended terrain
  • Smooth, progressive assist response
  • Appropriate weight distribution
  • Tight integration with frame and geometry
  • Durable, weather-resistant housing
  • Minimal sound and vibration
  • Reliable operation even in harsh conditions

Compare specifications, test ride different eMTB motor setups, and buy from quality brands to get optimal electric off-road assist.

Are Aftermarket eMTB Motor Kits Worth It?

Aftermarket kits allow adding electric assist capabilities to standard mountain bikes. But integrating kits on an existing bike has pros and cons:

Potential Benefits of eMTB Kits

  • Saves money over buying a complete pre-built eMTB
  • Lets you electrify a beloved bike frame
  • Gains knowledge wrenching on your own eBike

Common Drawbacks of eMTB Kits

  • Required tuning and troubleshooting during install
  • No tight integration with frame geometry
  • Voided bike frame warranty in some cases
  • Heavy hub motors hurt handling compared to purpose-built eMTBs
  • Risk of too much torque overstressing bike

For DIY mechanic types seeking a budget eMTB, quality kits can provide solid performance. But expect a more finicky setup compared to complete production eMTBs designed in unison.

Technical Differences Between eMTB Motors

While the general concept of eMTB assist remains the same, key technical differences exist between motors:

Cadence Vs Torque Sensors

Cadence-based systems activate assist based on RPMs. Torque sensors deliver power proportionate to human watt output.

Geared Hub Motors Vs Direct Drive

Geared hubs enable higher internal speeds to boost torque. Direct drive mounts simpler but may have more drag.

Pedal Rotation Detection

Motors sense pedal input via rotation sensors, torque measurement, or magnet/coil interaction to initiate assist.

Axial Flux Vs Radial Flux Motors

Compact axial flux vs conventional radial flux defines the magnetic field geometry within motors.

Neodymium Magnets

More powerful neodymium magnets in motors improve power density for a smaller, lighter overall unit.

The nuances distinguish one eMTB motor performance and feel from another. Leading brands chase every advantage.

Optimizing eMTB Motor Power Delivery

The key to a great eMTB motor is harmonious power delivery. Here’s how top systems achieve it:

Sensor Precision

High resolution torque and RPM sensors feeds detailed data to the control unit for fast reactions.

Tuning

Control software is optimized around the bike via custom power curves, ratios and sensor thresholds.

Assist Ramping

Gradual, linear power application avoids any abruptness. Feels natural.

Range of Support

Multiple assist modes allow tuning the degree of support for different terrain and exertion preferences.

Weight Distribution

Centralizing mass keeps the system balanced for composed handling when applying power.

Minimal Noise

Isolating motor noise and vibration keeps the ride peaceful and avoids rattling components.

The ultimate aim is power that arrives precisely when needed, yet fades into the background when not. The top eMTB motors achieve this better than ever.

Pros and Cons of High Torque eMTB Motors

High torque is great for technical climbing traction. But it has some tradeoffs:

Potential Benefits of High Torque eMTB Motors

  • Improves low-end power for steep hills
  • Allows front wheel lift for increased traction
  • Provides greater acceleration from slow speeds
  • Maximizes traction in loose, muddy conditions

Possible Downsides of High Torque Motors

  • Can alter bike’s handling dynamics
  • Magnifies pedal kickback forces
  • Increases component wear over time
  • Shortens motor and battery life
  • Adds weight

Finding the sweet spot between ample assisting torque without overpowering the bike is key. Excess torque costs efficiency and requires more battery capacity as well.

Do eMTB Motors Have Regenerative Braking?

Some common questions about eMTB motor braking:

  • Regenerative braking – Most eMTB systems lack true regenerative braking where the motor recharges the battery through deceleration forces. This may change in future generations.
  • Overrun cutoff – When coasting, the motor cuts off instead of continuing to drag or push the wheels. This avoids wasting battery but doesn’t recapture energy.
  • Motor drag when off – Quality eMTB motors have minimal resistance when not powered on and just coasting. Cheaper motors may have noticeable drag.
  • Brake motor cutoff – Brake levers have integrated switches that cut motor power when brakes are applied. This allows use of the brakes alone to slow the ebike.

So in summary – current eMTB systems employ smart freewheeling and auto cutoff to avoid wasting battery when braking or coasting but lack true regenerative capabilities for now.

Do eMTB Motors Require Special Care or Maintenance?

Relatively minimal maintenance is needed for eMTB motors:

  • Perform regular bike cleaning and lubricating to prevent grime buildup near motor.
  • Visually inspect wires and connections integrity. Avoid pressure from zip ties.
  • Check for odd noises or performance changes indicating issues.
  • Have annual eBike service to tune, update, and diagnose motor and systems.
  • Check that firmware and software is current when available.
  • Use a torque wrench for motor fasteners to prevent overtightening.
  • Let motor cool fully before washing or servicing.
  • Avoid soaking motor with high pressure water blasts during cleaning.

With care against contamination and impact, quality eMTB motors will deliver years of reliable assist without much required tuning or service.

Signs of eMTB Motor Problems

Watch for these signs of potential issues developing:

Performance Changes

  • Loss of power
  • Surging, stuttering, or uneven power delivery
  • Delayed or jumpy motor engagement
  • Increased noise or vibration

Mechanical Issues

  • Loose motor mount or fasteners
  • Severe motor rattling
  • Grinding noises when pedaling
  • Dragging sensation when motor off
  • Motor won’t turn freely by hand

Error Codes

  • Flashing LED patterns on display
  • Error code readout on display screen
  • App connectivity error messages

Don’t ignore any odd symptoms. Have the system inspected to avoid small problems becoming bigger failures.

Protecting eMTB Motors from Damage

Use care to prevent avoidable eMTB motor damage:

  • Avoid dropping or crashing your ebike – impacts can misalign motor parts.
  • Prevent contaminant ingress with fenders, guards, and frequent cleaning.
  • Check for loose motor mounting and secure all fasteners tightly.
  • Use shop towels to cover motor when washing rest of bike.
  • Let motor fully cool before washing. Temperature extremes shorten electronics life.
  • Be gentle using pressure washers – avoid direct blasts on motor.
  • Inspect wiring and cuts in insulation – cover any exposed wires.
  • Don’t attempt motor disassembly without manufacturer’s instructions.

With reasonable care against contamination, crash damage, overheating and overtightening fasteners, an eMTB motor should enjoy a long service life.

Diagnosing eMTB Motor Issues

If performance problems arise, systematically diagnose:

  • Review error codes – Display screens and apps may indicate fault codes pointing to the problem cause.
  • Inspect connections – Loose plugs or wires can intermittently cut power.
  • Charging tests – Try charging to confirm the battery and charger are good. Electrical issue can masquerade as motor failure.
  • Bounce test – Lift wheels to spin freely and feel for grinding, looseness or significant drag.
  • Spin crank test – Turn cranks by hand to check for smooth motor rotation without binding.
  • Wiggle test – Grasp motor to feel for any looseness indicating mount problems.
  • Wheel spin test – With bike secured, rotate wheels by hand to isolate sound and feel.
  • Process of elimination – Swap components like wheels with a known good bike to isolate the problem source.

Thoroughly work through electrical, mechanical and performance checks to identify any motor issues cause. Don’t overlook simple solutions.

eMTB Motor Longevity and Life Expectancy

With proper care, most eMTB motors meet or exceed these longevity estimates:

  • 500-1000 charging cycles. Lithium batteries slowly lose capacity over time.
  • 3000-5000 miles or 500-800 hours of riding. Varies based on power usage and conditions.
  • 3-5 years of typical regular use before noticing reduced range or power.
  • Motors may outlive batteries. Some brands offer modular batteries for replacement.
  • Electronics and connectors often outlast mechanical drive components.
  • Mid-drive motors may outlast hub drive versions subjected to more vibration.

Adhering to recommended service intervals maximizes lifespan. But eventually worn parts need replacement, with batteries needing it most frequently.

Choosing an eMTB Motor System by Bike Type

Match motors carefully to your specific build and riding style:

Cross country / Hardtails – Mid-drive power centered low is ideal. Look for lightweight motors optimizing torque for technical climbs without disturbing handling.

Downhill / Freeride – Durability is key to survive big hits. Heavier hub systems allow higher power. But mid-drives can work well too.

Fat bikes – Look for mid-drives that provide grip without overloading wheels. Ultra-wide hubs would require very dished wheels.

Full suspension trail – Need a motor complementing the frame’s kinematics. Custom tuned mid-drives integrate best.

Women’s eMTBs – Consider lighter, modular systems allowing you to shed weight for less assisted rides. Smooth torque aids technical skills.

Cargo eMTBs – Seek heavy-duty mid-drives designed for high loads, with reinforced mounting and optimized torque.

Matching your motor selection to the bike design and intended use will provide the ideal riding experience. Seek professional guidance to find the best motor/bike pairing.

Final eMTB Motor Recommendations

To conclude, look for motors providing:

  • Adequate power, efficiency, and torque for intended terrain and trails. More demanding riding benefits from extra torque.
  • Responsive yet smooth and progressive assist engagement. Avoid abrupt on/off reactions.
  • Tight integration with the bike frame, geometry, and suspension design for optimal power delivery and handling.
  • Appropriate weight distribution. Centered mass mid-drives enhance technical handling over rear hub systems.
  • Durable weather sealing and vibration resistance. Noise and reliability matter.
  • Reputable brand name and warranty coverage for peace of mind.

With an eMTB motor system tuned to your trails and matched carefully to the bike, you’ll enjoy the benefits of pedal-assist riding with minimal drawbacks. The technology continues improving rapidly. Happy trails!