When choosing between mid drive and hub drive motors, one of the key factors that can influence performance is the impact of pedaling cadence. Both motor types offer distinct advantages, but the efficiency of each is greatly affected by how fast or slow a rider pedals.
How Mid Drive and Hub Drive Motors Work
Both mid drive motors and hub drive motors provide assistance to the rider, but they do so in different ways, and these differences significantly impact motor efficiency, particularly when adjusting pedaling cadence.
-
Mid Drive Motors: Located at the bike’s bottom bracket, mid drive motors engage the bike’s gears, meaning the motor’s output is directly linked to the rider’s pedaling effort. The key advantage of mid drive motors is their ability to adjust power output based on the selected gear, allowing for more dynamic control over the riding experience.
-
Hub Drive Motors: Hub motors, located in either the front or rear wheel hub, provide direct power to the wheel. This system does not use the bike’s gears, meaning the motor’s output remains more constant regardless of pedaling cadence. Hub drive motors are typically more straightforward but offer less adaptability when tackling varying terrain or adjusting pedaling speeds.
SEE ALSO Which is Better: Hub or Mid-Drive E-Bike?
Pedaling Cadence and Motor Efficiency
Cadence, or the rate at which a rider pedals (measured in revolutions per minute, RPM), plays a crucial role in determining how efficiently the motor operates.
Mid drive Motors and Cadence
mid drive motors excel at adjusting to changing pedaling cadences due to their integration with the bike’s gear system. By shifting gears, the rider can optimize the motor’s power output to suit the terrain and riding conditions. The motor works in tandem with the rider’s effort to ensure that power is used efficiently, especially at 8090 RPM, which is considered the optimal cadence for most cyclists.
Experience has shown that when pedaling at a steady cadence of 200W, motor performance begins to decrease as cadence slows below 80 RPM, and efficiency drops even more significantly when pedaling at cadences lower than 70 RPM. This happens because mid drive motors rely on the cadence sweet spot to operate efficiently. In practical terms, the bike’s gears help keep the rider within this sweet spot, ensuring the motor operates at maximum power output without straining.
While climbing a hill, the motor’s performance is highly influenced by the rider’s cadence. As the cadence decreases, motor power falls off, and the rider may need to shift gears to maintain efficiency. The gears in a mid drive system are primarily designed to keep the rider within the motor’s optimal cadence range, helping to maintain a consistent power output.
Hub Drive Motors and Cadence
Hub drive motors are less adaptable to changes in cadence since they don’t engage with the bike’s gearing system. The motor’s power is instead tied directly to the wheel speed and ground speed, meaning that as the rider’s pedaling cadence increases or decreases, the motor’s power output remains largely unaffected.
Hub motors tend to perform best when ground speed is high, which often occurs on flat terrain or at higher speeds. When riding up hills or going slower than 10 mph, motor efficiency significantly drops off. Once a hub motor starts to struggle on an incline, downshifting doesn’t improve motor performance and may even worsen the motor’s output. The rider’s focus should be on maintaining high ground speed and maximizing assist levels as they approach a hill. The role of gearing in a hub drive system is not as crucial for motor performance but can help the rider maintain a comfortable cadence during the climb.
This means that on steep inclines, hub drive motors can become less efficient when the rider is not maintaining a high speed. Once the motor begins to bog down, the rider’s ability to keep the cadence in an optimal range becomes less significant because the motor’s power output is no longer able to compensate for the lack of speed.
Mid drive vs Hub Drive: Which is More Efficient Across Cadences
When considering motor efficiency, mid drive motors have a distinct advantage due to their integration with the bike’s gears. By shifting gears, the rider can optimize motor performance for various terrain types and pedaling cadences, making it easier to maintain power on both flat roads and steep climbs. The ability to adjust cadence and shift gears allows mid drive motors to perform efficiently across a wide range of riding conditions.
In contrast, hub drive motors don’t offer the same level of flexibility. While hub motors can perform well at high speeds, they lose efficiency at lower speeds and when climbing. Hub motors are designed for steady power output, but once they encounter resistance, such as during a hill climb, they struggle to maintain efficient power delivery without the benefit of shifting gears.
Gearing and Motor Efficiency
The gears on a mid drive motor system are crucial to maintaining motor efficiency. They allow the rider to shift gears to keep the motor within its optimal cadence range, regardless of external conditions like steep hills or changes in terrain. In this way, gears play a more important role than merely shifting the rider’s pedaling effort. They help the motor stay within its most efficient range, allowing for better performance at different cadences and on varying terrains.
Hub drive motors have fewer gearing options, typically limited to a 7 or 8 speed cassette. This limits the rider’s ability to finetune motor output across different pedaling cadences. While gears can help the rider maintain a comfortable cadence, they don’t offer the same motor optimization that comes with a mid drive system.
Conclusion
The efficiency differential between mid drive and hub drive motors is significantly influenced by pedaling cadence. mid drive motors offer greater adaptability by leveraging the bike’s gears to ensure the motor stays within an optimal cadence range, making them highly efficient across a wide range of speeds and terrains. Hub drive motors, however, are less responsive to cadence and rely on maintaining high ground speeds for optimal efficiency, making them less efficient on climbs or at lower speeds.
If you're considering a versatile ebike for your daily commute, the Qiolor electric adult bike with a hub-drive motor is an excellent choice. Its simplicity and reliable performance make it a great option for typical commuting needs, offering smooth and consistent power for a variety of urban terrains.
FAQs
How does pedaling cadence affect mid-drive motor efficiency?
Mid drive motors are designed to adjust their power output based on pedaling cadence, with optimal efficiency typically occurring at 80-90 RPM. This allows for more responsive and adaptable power delivery across various riding conditions.
Why is a hub motor less efficient at varying cadences?
Hub motors provide a consistent output of power regardless of pedaling cadence. Since they aren't connected to the bike's gearing system, they lack the adaptability seen in mid-drive motors, making them less efficient on varying terrain or when pedaling at different speeds.
How does a torque sensor improve mid-drive motor efficiency?
A torque sensor detects the rider’s pedaling effort and adjusts the motor’s power output accordingly, optimizing efficiency by ensuring the motor provides the right amount of assistance based on the rider’s input. This helps maintain a more natural and efficient ride.
Read More
What Are Amp-Hours and Their Importance?
How to Adjust Brakes on an Electric Bike
How Long Does It Take to Charge an Ebike Battery?
