Sirris F43 CMX 220mm Tool-Free LSC Fork | By Sirris Suspension | For Sur-Ron Light Bee X

Built to Dominate Any Terrain, Any Time

At REV Rides we see a lot of suspension upgrades come through the shop, but the Sirris F43 CMX Fork is in a completely different class. This fork was engineered specifically for high performance compact e-moto platforms like the Sur-Ron Light Bee X. It delivers full-size motocross performance in a compact chassis that is stronger, stiffer, and far more capable than stock suspension.

The F43 CMX pairs an oversized 43mm upside-down race chassis with Sirris’ proprietary CMX-tuned closed cartridge damping system. The result is razor sharp handling, incredible front end confidence, and the type of planted ride feel riders usually expect from full size race bikes. With 220mm of travel, tool-free compression adjustment, and race-grade materials throughout the fork, this setup completely transforms the way a Light Bee rides on rough terrain, jumps, or high-speed tracks.

Sirris started with their proven F43 race platform, then resized and lightened it specifically for compact electric motos. The longer 775mm chassis length, oversized stanchions, and billet clamps increase stiffness and stability while keeping weight balanced for aggressive riding. Everything about this fork was designed to reduce flex, increase durability, and maintain predictable performance even when riders start pushing these bikes to their limits.

Oversized Chassis Designed to Outperform

• 43mm hard chrome stanchions resist flex, dents, and nicks

• 7XXX-series hard anodized uppers maximize durability and structural strength

• 775mm extended fork length delivers a longer and more planted front end

• 220mm travel provides 20mm more travel than the stock Light Bee fork

• Billet aluminum triple clamps increase stiffness and reduce twisting under load

• 178mm fork spacing allows nearly unlimited tire choices for dirt or supermoto setups

• Direct mount stem compatibility for stronger cockpit integration

• Custom ultra stiff chromoly axle improves steering precision and front end feel

• Motorcycle style top cap system for improved steering bearing tension control

• Replaceable caliper brackets and wheel spacers allow for wheel or brake upgrades

It is not just about stiffness. The F43 CMX delivers real strength without compromise. The design focuses on balance, impact absorption, and long term durability so riders can push harder without losing front end confidence.

Race Grade CMX Closed Cartridge Damping

At the heart of the fork is Sirris’ CMX tuned symmetrical closed cartridge damper. This system was built to deliver professional level damping performance in a compact e-moto platform. Separate oil circuits isolate lubrication and damping oil, allowing the fork to maintain consistent feel even under long aggressive riding sessions.

• CMX Compact Motocross Tune designed for aggressive riders and racing environments

• Symmetrical closed cartridge design provides fade-free damping

• Independent oil circuits separate damping and lubrication oil

• High-flow pistons with fully tunable compression and rebound valving

• Hydraulic bottom-out control softens heavy impacts while preserving full travel

• 7XXX-series internal components with hard anodizing to reduce wear

• Premium Daido bushings and NOK MX seals for smooth operation and long service life

The CMX tune delivers a planted and predictable ride feel. Whether you are charging into rough terrain or pushing track speed, the fork remains stable, controlled, and endlessly tunable for rider preference.

Tool-Free Compression Adjustment

The F43 CMX introduces tool-free compression adjusters, allowing riders to quickly fine tune front end feel without needing a screwdriver. Nearly 30 clicks of external compression adjustment make it easy to dial in the fork for different terrain or riding styles.

Direct Mount Stem System

The Sirris steerer tube and motorcycle style top cap system are designed for direct mount stems. This improves cockpit stiffness and helps maintain consistent steering bearing torque, similar to full-size motocross bikes.

The stock Sur-Ron Light Bee X stem is not compatible because the Sirris steerer tube cannot be clamped. Recommended options include a Warp 9 direct mount stem or the Heavy Hitter Adjustable Billet Display Mount from GritShift.

Optional Drop Clamp for Big Wheel Builds

The optional drop crown clamp raises the front end an additional 25mm, extending overall fork length to approximately 800mm. This allows riders to run a 21 inch front wheel while maintaining proper bike balance when paired with longer rear suspension.

Axle and Brake Mount System

• Ultra stiff chromoly race axle improves steering precision

• Replaceable brake caliper mount brackets allow caliper upgrades

• 220mm rotor brake bracket included

• Stock Light Bee X rotor is 200mm and must be upgraded to 220mm

Technical Specifications

• Architecture: Upside Down Fork

• Travel: 220 mm

• Free Length: 775 mm

• Extended Length with Drop Clamp: ~800 mm

• Fork Spacing: 178 mm

• Weight: 4 kg per leg

• Stanchions: Ø43 mm high tensile steel, hard chrome

• Outer Tubes: Seamless 7050 aluminum, Type III hard anodized

• Drop Outs: 6061 aluminum, Type II anodized

• Axle: Ultra high tensile hard chromed race axle

• Triple Clamps: Billet 6061 aluminum, Type II anodized

• Steer Tube: Seamless 7050 aluminum

• Compression Adjustment: External tool free LSC adjuster

• Rebound: Dual side adjustable

• Seals: NOK MX seals

• Bushings: Daido MX bushings

• Fork Guards: High impact polypropylene, 210° wraparound

Spring Rate Options

• Medium: 140 to 180 lb rider weight, 3.6 / 3.2 springs

• Heavy: 180 to 220 lb rider weight, 3.6 / 3.6 springs

Rider weights are calculated without riding gear. Approximately 15 pounds of riding gear is factored into the recommended range. Upgrades such as heavier batteries or controllers should be added to rider weight when selecting spring rates.

CMX Tune Setup Notes

• Factory settings are measured in clicks from the fully closed position

• Once fully closed, back adjusters out according to factory recommendations

• Riders near a weight cutoff may adjust preload to fine tune sag

• Aggressive riders may benefit from moving up one spring class with reduced preload

• Rider preference and terrain may require further adjustment

Example: A 160 lb rider with 20 lb of added upgrades would calculate rider weight as 180 lb. An aggressive rider would typically run the heavy tune with lower preload, while a relaxed rider could run the medium spring with higher preload.

Fitment

• Sur-Ron Light Bee X & S

• Segway X160 & X260

• Talaria MX3 & MX4

Who This Fork Is Perfect For

• Sur-Ron riders building a race or track focused Light Bee

• Trail riders who want serious durability and front end confidence on rough terrain

• High power builds that need true motocross level suspension performance

Fitment: Sirris F43 CMX 220mm | Tool free LSC | Fork for Surron Light bee X & more

• Surron Light Bee X

• Surron Light bee S

• Segway X260

• Segway X160

• Talaria Sting MX3

• Talaria Sting MX4

• Eride Pro

• Eride pro S

• 79bike Falcon-M

This product may be compatible with more models than shown above. Please see the product description for full details, or contact us for help with fitment.