The Sirris F43 Premium Fork is a closed-cartridge e-moto fork built specifically for the Sur Ron Ultra Bee, made by Sirris and sold here at GritShift. It runs 43 mm chrome-plated stanchions in hard-anodized 7050 aluminum outer tubes, gives 246 mm of travel, weighs 22 lb and comes in Trail or MX tunes matched to rider weight.
Specs verified October 2026 against the live GritShift product page.
Specifications
| Fork type | Inverted e-moto fork, true symmetrical closed cartridge |
|---|---|
| Stanchions | 43 mm, chrome-plated steel |
| Travel | 246 mm |
| Weight | 22 lb |
| Outer tubes | Hard-anodized 7050 aluminum |
| Dropouts and triple clamps | Forged 6061 aluminum |
| Damping | Pressure-balanced closed cartridge with separate lubrication and damping oil circuits |
| Adjustment | External compression and rebound |
| Bottom-out control | Hydraulic bump stop at maximum stroke |
| Tunes | Trail or MX, each in several rider-weight configurations |
| Steerer | Dust seal and headset bearing pre-installed |
| Installation | Direct swap for the stock Ultra Bee fork, no additional modifications or parts |
What bikes does the Sirris F43 Premium Fork fit?
- Sur Ron Ultra Bee
Why put a closed-cartridge fork on the Ultra Bee?
Sirris built the F43 around a moto-inspired architecture for predictable damping, control and consistency under aggressive riding. The pressure-balanced closed cartridge keeps damping consistent through repeated impacts and long riding sessions, and it runs separate oil circuits for lubrication and damping so each job gets the oil it needs. A hydraulic bump stop softens hard landings at maximum stroke instead of letting the fork clang through its 246 mm of travel.
How do the Trail and MX tunes differ?
The F43 is sold in a Trail tune and an MX tune, and each tune is offered in multiple rider-weight configurations so the spring rate and valving match the rider. Sirris describes the result as a setup that can be configured for anything from technical trail riding to aggressive MX use. On top of the tune you order, external compression and rebound adjusters give direct control over how the fork behaves on the day.
What is in the box and how does the F43 install?
Installation is a direct swap for the stock Ultra Bee fork with no additional modifications or parts required. The dust seal and headset bearing arrive pre-installed on the steerer tube, and the supplied triple clamps and guards are shaped to accommodate the Ultra Bee's existing fairing and cable routing. The forged 6061 aluminum dropouts and clamps and the hard-anodized 7050 aluminum outer tubes are Sirris's combination of strength and durability for a fork that gets ridden hard.
Where can I buy the Sirris F43 Premium Fork Ultra Bee?
Right here. We sell the Sirris F43 Premium Fork Ultra Bee at GritShift, made by Sirris. Browse every fork and shock we carry in our Forks & Shocks collection.
