AFPM Mid-Drive — Animated Parts Breakdown
AFPM 2-SPEED MID-DRIVE MOTOR
The First 2-Speed eMTB Mid-Drive Motor
Axial flux motor with electromagnetic 2-speed shifting. Same peak torque as DJI Avinox. 11% more battery range. No competitor offers this.
AXIAL FLUX MOTORS POWER THE WORLD'S FASTEST MACHINES
HYPERCARS
Ferrari SF90 Stradale — YASA motor, 1,000 HP
Lamborghini Revuelto — 2x YASA, 1,015 HP
Koenigsegg Gemera — Dark Matter AFPM, 1,700 HP
Mercedes-AMG — Acquired YASA for $100M+
AEROSPACE
Joby Aviation — eVTOL air taxi, 5 AFPM motors
Lilium Jet — 36 AFPM motors for lift
Eviation Alice — All-electric commuter plane
NASA / DARPA — High-density AFPM research
ROBOTICS & INDUSTRY
Industrial robots — 20% of AFPM market
Drone propulsion — 5-10 kW/kg density
Marine electric drives — High torque
Medical devices — Zero cogging
We bring hypercar & aerospace motor technology to eMTB.
Designed and engineered in Korea.
CORE TECHNOLOGY
Axial Flux vs Radial Flux
Radial Flux Motor
Bosch, Shimano, DJI
Axial Flux Motor (AFPM)
YASA-type, Dual-Rotor Single-Stator
Cruising Efficiency Comparison
22% less power consumed on flat ground = 11% more range per charge = +7 km on 720 Wh battery
Dual-Rotor Sandwich
Two rotor discs carrying N48SH NdFeB magnets face inward and sandwich a yokeless, segmented stator. Because the magnetic flux crosses axially between the two rotors, the heavy stator back-iron (yoke) is no longer needed.
Result → ~50% less iron, a shorter flux path, lower core loss and a better heat path: a lighter, cooler, more efficient motor.
12-slot / 10-pole · N48SHHigher Torque Density
Torque = force × radius, and an axial-flux disc places its magnets at the large outer radius. So at the same size it makes ~5 Nm vs ~3 Nm for a radial motor — roughly +40% torque per kilogram.
Result → less gear reduction needed (~20:1 instead of ~50:1): fewer gear stages, quieter running, and a smaller, lighter gearbox.
5.0 Nm peak · ~+40% vs radialShorter & Flatter
The pancake stack is just 32 mm axially versus 50 mm+ for a radial cylinder of the same output. The motor becomes a thin disc instead of a long tube.
Result → it fits the bottom-bracket shell with a narrower Q-factor and frees axial space for the 2-speed mechanism — both decisive for a compact mid-drive.
32 mm axial · narrow Q-factorWORLD'S FIRST
2-Speed Electromagnetic Shifting
How It Works
EM Coil OFF (default)
Springs hold armature back. Ring gear free. Everything locks 1:1. Direct drive. Zero power draw.
EM Coil ON (48V, 3W)
Magnetic force clamps armature against ring gear. Ring locks to housing. Planetary reduces speed by 30%. More torque for climbing.
Auto-shift via current sensing
Controller reads motor current at 10kHz. Detects pedal dead spot. Shifts in 50ms. Rider feels nothing.
Why It Matters
The rear cassette doesn't help the motor
A mid-drive sits before the chain. The 12-speed cassette changes wheel torque for the rider, but the motor always sees the same load. It can't benefit from the cassette.
Single-speed motors waste energy cruising
At 90 rpm cruise, a single-speed motor runs at 2700 rpm with 15% load — spinning fast, doing nothing. Only 70% efficient.
+7 km per charge
On a 720 Wh battery. Riders notice this every ride.
ENGINEERING CHALLENGES
Why AFPM Is Harder to Build — and Why It's Worth It
There's a reason every eMTB uses radial flux motors. AFPM is harder to manufacture. But the performance advantage justifies the engineering effort — which is why Ferrari and Mercedes invested hundreds of millions in this technology.
Airgap Maintenance
Two airgaps (1mm each) between rotors and stator must stay consistent under thermal expansion, vibration, and 8000 rpm. Axial magnetic pull tries to close the gap. Requires precision bearings and stiff housing.
Magnet Retention at High RPM
Surface-mounted NdFeB magnets on spinning rotors experience centrifugal force at 8000 rpm. Carbon fiber sleeves or adhesive bonding required to prevent magnets from flying off.
Thermal Management
Stator is sandwiched between two rotors — heat can't easily escape. YASA's solution: segmented stator with direct cooling channels. Our design uses rotor fan effect + finned magnesium housing for 180W dissipation.
Yokeless Stator Assembly
Each of the 12 stator teeth is a separate piece — no continuous yoke holding them together. Requires precise fixturing during assembly to maintain tooth spacing and alignment.
EM Clutch Integration
The electromagnetic friction clutch must hold the ring gear against 5 Nm motor torque without slipping, while fitting inside the existing housing envelope. Ogura-style brake design proven in industrial applications.
Shift Timing Control
The controller must detect the pedal dead spot (zero torque window) within each half-revolution and execute the shift in <50ms. Requires high-resolution current sensing at 10kHz+ sample rate.
Every challenge above has been solved by YASA, Magnax, or Emrax in production.
Mercedes bought YASA for over $100M in 2021 and is building 100,000 AFPM motors per year in Berlin. This is not experimental technology — it's proven. We're applying it to a new market.
SPECIFICATIONS
Head-to-Head vs DJI Avinox M2S
| Spec | DJI Avinox M2S | CONTAVELO ELECTRIC |
|---|---|---|
| Peak Torque | 150 Nm | 160 Nm (LOW) / 123 Nm (HIGH) |
| Peak Power | 1,500 W | 1,500 W |
| Motor Type | Radial Flux BLDC | AFPM (YASA-type) |
| Gear Ratios | 50:1 fixed | 30:1 / 39:1 (2-speed) |
| Shifting | None | Auto EM (50ms) |
| Motor Torque | ~3 Nm | 5 Nm |
| Motor Stack | ~50 mm | 32 mm |
| Cruise Efficiency | ~70% | ~90% (HIGH) |
| Range Advantage | Baseline | +11% (~+7 km) |
| Frame Compat | Avinox only | Avinox-compatible |
HISTORY OF AFPM
From Oxford Lab to Ferrari — The AFPM Story
YASA founded at Oxford University by Dr. Tim Mayberry. The Yokeless And Segmented Armature (YASA) topology eliminates the stator yoke — the heaviest single component in a conventional motor.
Ferrari selects YASA motors for the LaFerrari successor program. The SF90 Stradale becomes the first production car with YASA AFPM technology — 1,000 HP hybrid.
Koenigsegg develops the 'Dark Matter' AFPM motor producing 800 HP from a single unit — the most power-dense electric motor ever built. Uses axial flux topology.
Mercedes-Benz acquires YASA for over $100 million. Begins retrofitting a Berlin factory to produce 100,000 AFPM motors per year for AMG electric vehicles. AFPM goes from niche to mass production.
Lamborghini Revuelto and Temerario ship with YASA AFPM motors. Joby Aviation eVTOL and Lilium Jet use AFPM for aerospace. Market grows 12.1% annually.
We apply proven AFPM technology to eMTB — a market where nobody has done it. Combined with the world's first electromagnetic 2-speed shifting. Designed in Korea.
Ready to build the future of eMTB?
We're looking for investment partners and OEM collaborators to bring the world's first 2-speed AFPM mid-drive from concept to production.
Contavelo Electric · Contavelo · South Korea