The Sirris F43 CMX Fork Upgrade is a bolt-on closed-cartridge fork for the Sur Ron Light Bee X, made by Sirris and sold here at GritShift. Built from the ground up for electric dirt bikes, it delivers 220 mm of bottom-out-resistant travel, 17 mm more than stock, at 178 mm width and weighs 20 lb.
Specs verified October 2026 against the live GritShift product page.
Specifications
| Fork type | Bolt-on fork designed specifically for the Sur Ron LBX |
|---|---|
| Travel | 220 mm, bottom-out resistant (17 mm more than stock) |
| Weight | 20 lb |
| Width | 178 mm, fits knobbies or supermoto tires |
| Dampers | Closed cartridge, tuned for rider weight and style |
| Compression | Tool-free adjustment |
| Spring rate options | Medium tune (140 to 180 lb riders) or Heavy tune (180 to 220 lb riders) |
| Clamps | Scalloped billet triple clamps |
| Bar mount | Direct mount compatible, standard bolt pattern |
| Axle and dropouts | Stiff axle and dropouts for improved steering feel |
| Brake mount | Swappable caliper brackets |
| Stem | Threaded stem conversion for proper preload |
| Testing | GritShift shop-tested for over 6 months on our own bikes before release |
What bikes does the Sirris F43 CMX LBX fork fit?
- Sur Ron Light Bee X
Why replace the stock Light Bee X fork with the F43 CMX?
Sirris calls the F43 CMX the only bolt-on fork designed specifically for the Sur Ron LBX, built from the ground up for electric dirt bikes with the geometry, travel, stiffness and damping to back it up. The 220 mm of bottom-out-resistant travel is 17 mm more than the stock fork, and we shop-tested it for over 6 months on our own bikes before we put it on sale here at GritShift.
Which spring rate should a Light Bee X rider order?
Two tunes are offered. The Medium tune covers riders from 140 to 180 lb and is aimed at trail and all-around riding. The Heavy tune covers 180 to 220 lb and suits senders, heavier riders, or anyone who wants extra headroom. Both tunes use closed-cartridge dampers set for rider weight and style, with tool-free compression adjustment for fine changes at the trailhead.
What else changes at the front end with the CMX fork?
The 178 mm width clears knobbies or supermoto tires. The scalloped billet clamps are direct mount compatible on the standard bolt pattern, the stiff axle and dropouts improve steering feel, and swappable caliper brackets keep brake upgrades simple. A threaded stem conversion lets the headset be preloaded properly instead of relying on the stock arrangement.
Where can I buy the Sirris F43 CMX Fork Upgrade Sur Ron LBX (220mm Travel)?
Right here. We sell the Sirris F43 CMX Fork Upgrade Sur Ron LBX (220mm Travel) at GritShift, made by Sirris. Browse every fork and shock we carry in our Forks & Shocks collection.
