Outrunner Vrs Inrunner BLDC motor

Thread Starter

Junaid Arshad

Joined Jul 7, 2023
For E-bike should I be using Outrunner or Inrunner BLDC motor, as both have their own advantages and disadvantage, which one will have a better output?



Joined Jan 27, 2019
Welcome to AAC.

The differences between in- and out runner motors doesn't make one or the other a better choice for your application.

To decide on a motor, you need to concern yourself with the specifications concerning physical dimensions and power output, not the motor construction. Once you have this information, you can look at available options and decide based on actual requirements.

The outrunner motor will generally have a larger diameter, but potentially provide more torque. This is because of the space for more or larger magnets, and the larger moment arm provided by the larger diameter rotor.

On the other hand, an outrunner exposes the rotor itself and may be a challenge from a safety and physical mounting perspective. It may also be subject damage by the infiltration of dirt. All of these concerns, though can be mitigated with a housing that covers the motor—though this makes it even larger.

The inrunner will contain everything but the output shaft(s). It will be more compact, and less vulnerable to damage. This may or may not be important in your application.

Compare all available motors by:

  1. Cost
  2. Efficiency
  3. Power Output
  4. Availability
  5. Physical Size
  6. Safety Concerns
  7. Reliability

Then choose the most optimal. This is all to say, out- vs inrunner should not be a pivot point for your design.