Sirris F43 220mm Fork | CMX Tune | Tool free LSC | Surron Light Bee X & More

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