The Losi 1/4 Promoto-MX and Promoto-SM Supermoto are engineering marvels that combine a high-RPM mechanical flywheel with Spektrum MS6X stabilization. However, at over 3.5 kg (7.8 lbs) of RTR mass hitting motocross whoops, triple jumps, and high-lean asphalt corners at 40+ mph, the forces transmitted through the front fork triple clamps, rear swingarm pivot, and rising-rate shock linkage are immense.
At Rakonheli, we engineered a dedicated line of CNC 7075-T6 billet aluminum and Grade 5 titanium structural components specifically for the Losi 1/4 Promoto platform.
1. Front Fork Rigidity: 7075-T6 Triple Clamps & Lower Fork Lugs
On a two-wheeled RC chassis, front fork stiction is the enemy of stability. When the stock plastic triple clamps or lower fork caliper/axle lugs twist during a hard landing, the left and right fork tubes bind asymmetrically. By upgrading to Rakonheli CNC 7075-T6 Triple Clamps and CNC Fork Lugs, both fork stanchions remain strictly parallel throughout the entire suspension stroke.
- Aerospace 7075-T6 Alloy (572 MPa Ultimate Tensile Strength): Nearly twice the yield strength of standard 6061 aluminum, preventing steering stem and fork tube clamping distortion after heavy cartwheel crashes.
- Precision Steering Damper Geometry: Maintains consistent cable and servo-saver tension so the bike tracks straight through deep ruts.
2. Rear Suspension Kinematics: CNC Swingarm, Knuckle & Pull Rod
The Promoto's rear suspension relies on a motocross-inspired rising-rate linkage knuckle and dogbone pull rod. Under hard acceleration, chain tension and rear tire hookup compress the linkage under hundreds of Newtons of load.
| Promoto Upgrade Zone | Failure Mode of Stock Plastic | Rakonheli 7075-T6 CNC Solution |
|---|---|---|
| Upper & Lower Triple Clamps | Fork tube misalignment & stem ovalization on nose-heavy landings | Split-clamp CNC 7075-T6 billet clamps with positive pinch bolts |
| Rear Linkage Knuckle & Pull Rod | Bushing slop & linkage snap at full bottom-out | Precision ball-bearing CNC 7075-T6 triangle knuckle & dogbone |
| Chain Guide, Sprocket & Caliper Guard | Chain derailment & stone damage to rear rotor | Hard-anodized 7075-T6 guard and precision CNC chain adjusters |
