Active Sliders: How we Scaled Our 2-Speed Transmission for Scooters
Revolutionizing EV Drivetrains, No Matter How Many Wheels
When we expanded from passenger vehicles into two-wheel applications, we stepped into an entirely different reality: highly price-sensitive markets, tight margins, and extremely constrained packaging centered around a scooter’s swing arm. Weight limits are strict and cost is a first-order constraint—not something optimized later. That meant in order to move Ingear technology quickly into this market cost, size, and weight had to define the design DNA from day one.
Working closely with experts in the two-wheel space, we also learned that performance comes first. Riders want stronger launch torque and better gradeability from a low gear, together with higher top speed from a second gear. Range improvements still matter, but the value stack shifts compared to four-wheel programs. That reordering shaped our ratio selection and mechanical architecture from the outset—and aligns with our broader strategy: deliver a low-risk, manufacturable mechanical solution that preserves both efficiency and performance gains without compromise.
Designing for the Scooter Reality
Scooter powertrain architectures come in two forms, mid-mounted motors and wheel mounted motors. Our solution is for the mid-mount configuration and because of the swing arm enclosure for the drive belt, if we wanted to package in the mid-mount architecture the most obvious placement was to put the transmission at the wheel hub. With the transmission mounted directly at the wheel, there’s little drivetrain compliance to mask torque dips; our shifts must be seamless. And because the system rides on the swing arm, road shock feeds directly into the transmission. We engineered the shifting components to survive severe impact loads and validated the design with drop-style tests, ensuring no false shift events—an essential reliability requirement since our transmission was now a part of the un-sprung mass system.
We also made a key architecture choice: run dry. Eliminating the oil bath simplifies integration, reduces weight, and helps maintain high efficiency. Achieving this required careful attention to materials and thermal loads, drawing on lessons from our broader Ingear development.
The Breakthrough: Active Slider Shifting
From the design team emerged the breakthrough we needed: Active Slider shifting.
Because of the swing arm packaging, there is more belt wrap. This means that we have less time because the arc of the sprocket that is not in contact with the belt is shorter. This combined with motor and inverter torque-slew limits, demanded a longer, precisely timed shift profile that was not available in our four wheel shift mechanism. Active Sliders deploy split key segments (the segments whose only job is to lead the upshift and the downshift). This gives us independent control over which segment moves when and that precision lets us shape a longer, smoother shift that keeps wheel torque constant. No new motors needed, we can use the motor and inverter already present on the vehicle—without retuning.
This timing flexibility also opens the door for packaging innovations: multi-layer segment geometry that fits within a narrow envelope while maintaining belt or chain clearance and high wrap on the drive sprocket. In short, Active Sliders give us both the shift behavior we need and the geometric freedom the scooter form factor demands.
What This Buys the Rider and the OEM
Imperceptible shifts, even at wide-open throttle
Active Sliders and our torque-fill strategy keep wheel torque flat, essential when drivetrain compliance can’t mask disturbances.
Real-world performance gains
Higher top speed from the second ratio, stronger launch and ~30–50% better gradeability from the low ratio, and improved drivability—all without inverter changes.
Packaging-first engineering
Nested tensioning, increased belt wrap, and geometry that preserves the stock motor-to-wheel center distance within the existing swing-arm envelope.
Lightweight, dry-system durability
A design intended to live on unsprung mass, with selective use of engineered polymers where torque density allows—reducing cost while maintaining robustness.
How We Made It Simple—and Kept It Simple
Low-power actuation: Shift events draw only brief, headlight-scale power, then shut off.
Parts consolidation: Shared slider tracks and stamped linkages replace unnecessary mechatronic complexity, cutting size, cost, and weight.
Clear separation of shift vs. non-shift elements: This removes failure modes, improves shock tolerance, and makes robustness a design input—not a late-stage test discovery.
OEM-aligned control strategy: Our system works with existing torque-slew behavior. No inverter changes, no new control loops—just a clean integration path.
What’s Proven—and What’s Next
Mechanism maturity: Active Slider latching, shock tolerance, and timing have been validated in rig testing with no false events.
System readiness: The complete two-wheel transmission design is now released internally. Next comes full-system testing, followed by a working vehicle as the demonstration gateway for OEM programs.
Partner alignment: Where belts meet transmissions—especially alongside established belt suppliers—the commercial opportunity is immediate once benefits are validated.
Focused delivery: Rather than building a fleet of demo units, our strategy is to deliver one compelling proof point, then move directly with select OEMs into vehicle-specific, production-intent programs.
The Engineering Culture Behind It
Active Sliders didn’t appear overnight. The concept has lived in our IP portfolio for years, but what unlocked it was the compounding of lessons from successive Ingear actuation and shifting generations. It reflects an engineering culture that values critique over ego, simplicity over ornamentation, and “make it work” rigor over authorship.
That philosophy—consistent across our passenger-car Ingear programs, durability breakthroughs, and our newest fixed-ratio innovations—is what allowed us to choose the right innovations for the right job, ensuring many new and innovative ways to apply the Ingear technologies.
About Inmotive Inc.
Inmotive is a pioneering developer of ultra-efficient multi-speed powertrains for electric vehicles. The company’s flagship product, the Ingear™ transmission, delivers superior efficiency and performance for a wide range of EV applications. Committed to advancing sustainable mobility, Inmotive partners with leading manufacturers to redefine what’s possible in electric and alternative energy transportation.