The XP3.

The XP3 was never meant for production. It was the test bed — the board where swing-arm suspension, custom motor design, and airless rubber wheels were pushed to their limits. Everything that makes the Mach One what it is was validated here first.

The SR125 airless rubber wheel was born on the XP3. The suspension geometry was refined here. The motor cooling system was stress-tested at speed. Every breakthrough in the Radium lineup traces back to this board.

The XP3 ran the same Formula 1-inspired structural carbon fibre monocoque that would go on to define the Mach One — built around interchangeable decks bolted straight in. The super-light deck, finished with a urethane edge, weighed just over 1kg.

The swing-arm suspension system — shock absorption and direct handling from a single moving part — was pushed to its limits on the XP3 long before it ever reached a production board. Refine, ride, repeat.

Dual 6485 brushless motors, designed and refined in-house for power and durability. An advanced modular PCB battery system ran the best 21700 cells for maximum performance, while high-performance polyurethane timing belts handled direct power transmission and longevity.

Radium Torque Steering independently controlled each motor for power-assisted steering and increased traction — the system validated here before it ever reached production. The trucks paired a stable, agile split-angle geometry with a split-bushing design drawn from modern downhill skating.