QS138 90H V3 mid drive motor is a high‑performance 4000W permanent magnet synchronous motor built for electric motorcycles, dirt bikes, and high‑power e‑mobility conversions.
Its biggest highlight is the integrated internal gearbox design, which delivers stronger torque and better overall performance than standard direct‑drive motorsQS MOTOR.
Key Advantages of the Integrated Gearbox
· Higher torque & stronger climbing ability
With a 1:2.35 reduction ratio, the qs138 90h motor turns high RPM into strong low‑speed torque, greatly improving start acceleration and gradeability. It easily handles steep slopes up to 25° even under full load, making it ideal for heavy e‑motorcycles and off‑road use.
· Simpler vehicle structure & space saving
The all‑in‑one design eliminates the need for an external gearbox, transmission shaft, or clutch. This cuts down parts, simplifies assembly, and leaves more room for batteries, helping you build a cleaner, more compact powertrain.
· Smoother power delivery & higher efficiency
The internal gear set optimizes motor working range, keeping efficiency between 85%–92% in most riding conditions. It reduces motor load, lowers heat, extends battery range, and improves durability.
· Flexible installation & better layout
The compact, fully integrated structure supports both mid‑mount and rear‑mount layouts. It fits easily into standard motorcycle frames and saves valuable space for battery packs and other components.
Superior Performance & Reliability
– Supports regenerative braking to save energy and extend range
– High‑strength internal gears ensure stable, low‑noise operation
– Class F insulation and thermal protection for long‑term heavy use
– Compatible with mainstream controllers for easy system matching
Ideal Applications
1) Electric dirt bikes & light electric motorcycles
2) High‑power e‑ATVs, go‑karts, and off‑road vehicles
3) Performance‑focused e‑mobility conversion projects
The QS138 90H 4000W V3 mid drive motor with internal gearbox is the perfect choice for builders who want strong torque, simple installation, high efficiency, and professional off‑road performance in one compact, reliable unit.
