Multigear Transmission for E-bike

Transmission Motor for E-bike(over 3 gear)

Developed by ‘Direct Trans Hub’ technology of Bygen(World’s first)

Necessity of Transmission Motor

The moment you encounter our transmission motor, you will feel keenly the necessity of shift gears.
Gear shifting frees torque (force) and speed.
At the start or on the hill, it reduces RPM to increase the torque and the increased speed generates momentum. This will in turn enables it to increase RPM with low torques, leading to driving at higher speeds.
Therefore, it rapidly extends the mileage per battery charging.

Core technology

  • This can be implemented number of speed steps and transmission ratio that you want.
  • Motor, reduction gear and transmission are connected to one identical rotating axis series.
  • The core technology of our transmission motor is in the transmission.
    The key is shifting gear as shifting part and rotating axis rotate at the same speed.
    Easy to shift during uphill climbing.
    – Shifting gears require clutching, but motor plays the clutch’s role as the voltage is instantaneously dropped when shifting gear.
    Therefore, when gear shifting is connected to controller, it becomes simple.

Technology necessary for electric bicycles applied

  • Gear shifting is possible even when stopped. (easy start on the uphill climb)
  • The torque of the motor is not transmitted to the crank. (Accident prevention)
    – Prevent fast-spinning of both feet according to the rotating speed of the motor.
  • The torque of the crank is not transmitted to the motor. (to prevent overload)
    – Easy pedaling even when motor power is off.

Transmission motor type

● For chain bicycle

Structure Type Conformation Installation place Note
Transmission motor Mid drive BB type Frame Exclusive frame
Transmission motor Mid drive Kit type Existing BB  General frame

● For chainless bicycle

Structure Type Conformation Installation place Note
Transmission motor Hub drive Hub type Center of wheel Exclusive frame
(Only for chainless bicycle)

♦ Design and production of transmission ratio and step desired of above motors are possible applying to the same technology of ‘Direct trans hub’.

Product competitiveness

  • Superior performance
    Performance is excellent since the drive efficiency of the motor is high
    connecting the motor and the transmission in serial on the same axis.
  • Quick transmission system
    Easy to shift during uphill climbing (instant shift to speed ratio wanted).
    * Sprocket transmission weakness solved.
  • Extend battery life
    The high drive efficiency of the motor extends battery life.
  • Simplification
    Extra shifting parts are not necessary because the motor itself is shifted.
    So there is no problem such as chain breakage and chain trouble when shifting.
  • Miniaturization,light weight
    BB type(Bottom Bracket) is possible to be downsized and lightweight because it’s small and light and also motor bracket is light in round type.
  • Easy frame making
    Motor bracket of BB type is easy to make frame because of the same form as general frame BB
    Especially carbon frame making is easy.
  • Diversity
    It developed a BB type with excellent design and efficiency, and a kit type that can be installed to general bicycle as it is.

Bygen’s Mid Drive

  ● BB type
    – Compact and lightweight and easy to make frame because motor & transmission unit
connected in series on one shaft

    – Assembly Drawing(BB Type)

    – Bicycles with BB type motor installedbbType_bike

  ● Kit type
    – Easy installation in existing frame

Assembly Drawing(Kit Type)

Kit Type