Sirris F43 CMX Tune Inverted Front Suspension Fork

Take your compact electric motorcycle to pro-level performance with the Sirris F43 CMX Tune Inverted Front Suspension Fork. Built specifically for aggressive off-road e-motos, the F43 downscales full-size motocross suspension technology into a compact chassis. Featuring oversized 43mm hard-chromed high-tensile steel stanchions paired with 7050 hard-anodized aluminum outer tubes, this fork delivers extreme torsional rigidity, razor-sharp steering precision, and complete resistance to front-end flex under heavy braking.

At the heart of the F43 is Sirris’s proprietary CMX (Compact Motocross) symmetrical closed-cartridge damper. By separating damping oil from lubrication oil via dual internal circuits, the F43 eliminates cavitation and thermal fade during long, hard rides. Delivering 220mm of terrain-devouring travel (20mm more than stock forks), an integrated hydraulic bump stop, and tool-free external compression adjusters, the Sirris F43 sets a new benchmark for light e-moto suspension.

Sirris F43 CMX Key Performance Highlights

• Oversized 43mm Stanchions: Hard-chromed high-tensile steel lower tubes resist flex, dents, and binding during extreme landings and high-speed cornering.

• CMX Closed-Cartridge Damping: Symmetrical closed-cartridge damper provides consistent, fade-free damping performance across all temperature conditions.

• 220mm Extended Wheel Travel: Increases front-end travel to absorb massive G-out hits and deep rutted terrain without bottoming.

• Dual Independent Oil Circuits: Keeps lubrication oil separate from hydraulic damping fluid to maximize oil life and maintain smooth suspension action.

• Hydraulic Bottom-Out Bump Stop: Ramps up oil resistance near maximum stroke to cushion heavy impacts smoothly.

• Wider 178mm Stance: Expanded fork leg spacing accommodates wide knobbies or supermoto tire builds without tire rub.

• Tool-Free External Adjustment: Easily fine-tune low-speed compression clickers on top of the fork legs without tools.

• Heavy-Duty Hardware: Includes a custom ultra-stiff hard-chromed axle, 220mm rotor brake bracket, and 210-degree wraparound guards.

Important Fitment & Compatibility Notes

Rider Weight & Spring Rate Chart

Sirris utilizes a split coil spring configuration (left leg / right leg) optimized for rider weight without gear (calculations account for ~15 lbs of standard riding gear).

Sirris F43 CMX Technical Specifications Matrix

Why Order From Electri Cycle Works?

• Authorized E-Moto Suspension Experts: Work with our technical team to select the perfect spring tune and direct mount stem setup for your build.

• Fast Dispatch & Showroom Pickup: Order online for quick nationwide shipping or choose direct local pickup at our Salt Lake City showroom.

• Complete Installation Support: We supply all required spacers, brackets, and technical guidance to ensure a seamless fork swap.

Frequently Asked Questions

Why does the Sirris F43 fork require an aftermarket stem?

The Sirris steerer tube design uses a motorcycle-style top cap system to better regulate headset bearing tension. Stock Sur-Ron and E-Ride Pro stems cannot clamp onto the steerer tube properly, so a 4-bolt direct mount stem (e.g., Warp9) is required.

Can I run my stock 200mm brake rotor with this fork?

No. The F43 includes a specialized 220mm caliper mounting bracket designed specifically for 220mm brake rotors. You must upgrade to a 220mm rotor when installing this fork.

Why are Woody’s Wheel Works wheels not compatible?

Woody’s Wheel Works uses custom hub shell dimensions and end-cap spacings that interfere with the custom hard-chromed axle and dropout alignment of the Sirris F43 chassis. Standard factory hubs and most aftermarket wheels fit cleanly using the included axle spacers.