EXT Arma MX vs TECH ER30 vs Sirris R46: Which Rear Shock Is Right for Your Surron or E-Ride Pro?
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Hey, Bryce here! If you've been riding your Surron Light Bee X, Ultra Bee, or E-Ride Pro on anything more technical than a fire road, you've already noticed the limits of the stock rear shock. The OEM unit is soft, lacks adjustability, and was calibrated for a rider weight and riding style that probably doesn't match yours. The good news: there are three excellent aftermarket shocks available right now that cover the full spectrum from trail-oriented upgrade to serious enduro performer. Here's how they compare.
The Contenders: Who These Shocks Are For
The three shocks we carry at ThrottleCo that consistently show up on serious builds are the EXT Arma MX E-MX, the TECH ER30, and the Sirris R46. Each is engineered specifically for electric dirt bike applications — meaning they account for the weight distribution, low center of gravity, and torque delivery characteristics of e-motos rather than being carryovers from gas bike suspension design.
EXT Arma MX — The 4-Way Adjustable Benchmark
The EXT Arma MX is the shock that's been on the most serious Surron and Talaria builds we've seen. EXT is an Italian suspension manufacturer with a motorsport pedigree, and the Arma MX brings four-way damping adjustment: high-speed compression (HSC), low-speed compression (LSC), high-speed rebound (HSR), and low-speed rebound (LSR). That's race-level tunability on a platform that benefits enormously from getting the damping right.
Key specs (Arma MX E-MX):
- Piston diameter: 32mm
- Spring: Specify your weight for correct spring rate at order
- Body: Billet aluminum with hard anodize
- Adjusters: External 4-way (HSC, LSC, HSR, LSR)
- Reservoir: Nitrogen-charged piggyback
- Compatible: Surron Light Bee X, Ultra Bee, Talaria Sting MX3/MX4/MX5, Talaria XXX, E-Ride Pro SS/SR
The Arma MX's high-speed compression adjustment is its standout feature on e-motos. Because electric motors deliver peak torque instantly, the bike loads the suspension aggressively off corners and over square-edged hits in ways that a single-damping-rate shock handles poorly. Being able to soften HSC independently of LSC lets you address that without sacrificing small-bump sensitivity.
TECH ER30 — CTS Technology for E-Moto Weight
TECH Suspension developed the ER30 series specifically with e-moto weight and geometry in mind. The ER30 uses TECH's proprietary CTS (Cone Throttling System) for compression damping — a conical valve arrangement that delivers more progressive compression than a standard shim stack, particularly useful when landing off drops or hitting rough braking bumps at speed.
Key specs (TECH ER30 — available in 283mm and 288mm stroke):
- Piston diameter: 30mm
- Spring rate: Available in multiple rates — specify rider weight
- Body: Machined aluminum alloy
- Adjusters: External LSC, HSC (internal shim access), LSR
- Reservoir: Remote nitrogen canister
- Available strokes: 283mm (Surron LBX, E-Ride Pro variants) and 288mm (Ultra Bee)
- Compatible: Surron Light Bee X, Surron Ultra Bee, E-Ride Pro SS/SR/S
The CTS progression makes the ER30 feel plusher in stock tune than the Arma MX, which suits riders who want good performance without spending time on clicker settings. Two stroke length options (283mm and 288mm) ensure you're getting the right geometry for your specific platform rather than adapting the wrong-length shock to your bike.
Sirris R46 — 46mm Piston, Built for Race Pace
The Sirris R46 takes a different approach: 46mm piston diameter, the largest of the three shocks here and closer to traditional motocross sizing. A bigger piston means more damping surface area, more consistent force at higher velocities, and less heat buildup under sustained hard use. If you're putting in long days on rough terrain or racing, the R46's thermal stability is a real advantage.
Key specs (Sirris R46 for Surron Ultra Bee):
- Piston diameter: 46mm
- Spring: Custom rate per rider weight at order
- Body: CNC-machined billet aluminum
- Adjusters: External LSC, LSR; HSC internal
- Reservoir: External nitrogen canister
- Linkage: Pairs with Sirris linkage triangle for Ultra Bee geometry optimization
- Compatible: Surron Ultra Bee (also available for Surron LBX)
The R46 pairs naturally with the Sirris linkage triangle for the Ultra Bee. If you're already running Sirris geometry hardware, staying in the same ecosystem makes sense for setup consistency. It's the most race-focused option here and the one most likely to benefit from professional valving if you're serious about getting it exactly dialed.
Head-to-Head Comparison
| Spec | EXT Arma MX | TECH ER30 | Sirris R46 |
|---|---|---|---|
| Piston diameter | 32mm | 30mm | 46mm |
| Damping adjusters | 4-way external | LSC + HSC + LSR | LSC + LSR external |
| Reservoir type | Piggyback nitrogen | Remote nitrogen | Piggyback nitrogen |
| Stroke options | Multiple | 283mm, 288mm | Model-specific |
| Best for | Max tunability, aggressive riding | Trail versatility, progressive feel | Race pace, extended hard use |
Which Shock Should You Run?
If you want the most adjustable shock available and you're willing to spend time dialing clicker settings for your terrain and riding style, the EXT Arma MX is the benchmark. The 4-way adjustment is genuinely useful on e-motos where instant motor torque loads the suspension differently than gas bikes.
If you want excellent out-of-the-box feel with minimal setup for mixed-terrain trail riding, the TECH ER30 delivers that through its CTS progression without sacrificing performance when you push harder.
If you're building a Surron Ultra Bee specifically for performance and you want the most race-capable option with the largest piston available, the Sirris R46 paired with the Sirris linkage triangle is the premium Ultra Bee rear suspension package.
All three are significant surron suspension upgrades over stock, and all three ship fast from the USA. Reach out if you need help choosing the right spring rate for your rider weight — we've set up enough of these to point you in the right direction. And if you're not ready to pull the trigger on a full shock upgrade, the ThrottleCo Sponsor Program gets you 3% off every order plus a referral commission.