Sirris R38 Rear Shock | E-Ride Pro 3.0

Big Moto Performance, Bombproof Durability

The Sirris R38 brings true big-bike suspension technology to the E-Ride Pro 3.0. It uses proven internal architecture from the larger Sirris R46 platform, packaged into an oversized piggyback shock engineered for compact electric motos. When the trail gets rough, speeds climb, and repeated hits begin building heat, the R38 is designed to keep delivering controlled and consistent damping.

Sirris built the R38 for riders who need more support, traction, and adjustability than a typical small-platform shock can provide. Its high-flow internals move a massive amount of oil, helping the shock respond quickly without giving up control during hard riding. The result is a planted rear end with the moto-level feel and consistency normally associated with full-size motocross suspension.

Important: The stock E-Ride Pro linkage will not work with the Sirris R38 shock. Sirris partnered with Prickly Motorsports to develop an R38-specific linkage, which is sold separately. The custom linkage provides the correct fitment and geometry for the 289 x 78 mm shock while raising the rear of the bike by 25 mm.

A CMX fork drop clamp can also be added to raise the front by an equivalent 25 mm. This helps riders create a balanced chassis setup when using the taller R38 rear suspension configuration.

Link to linkage rocker you need here!

High-Flow CMX Damping

The R38 shares its high-flow base valve cavity architecture with the larger R46. This design provides exceptional pressure balance, faster frequency response, and the oil flow needed for a controlled moto-style feel. Pro-level CMX, or Compact Motocross Tune, damping includes fully tunable compression and rebound circuits that remain cool and consistent under repeated hard hits.

Two Stage Compression, also called 2SC, provides independent high-speed and low-speed compression adjustment. Low-speed compression helps tune chassis movement during braking, acceleration, rolling terrain, and rider weight transfer. High-speed compression controls sharper impacts such as square edges, hard landings, rocks, and roots. The separate rebound adjustment lets riders control how quickly the shock recovers after compression.

Each R38 is tuned specifically for its bike model and designed to pair with Sirris F43 CMX forks. Together, the shock and fork create a more balanced suspension package with improved traction, control, and confidence at speed.

Rider Weight and Spring Options

Sirris offers two spring ranges for the E-Ride Pro 3.0. The listed ranges are based on rider weight without riding gear. Sirris calculates an additional 15 pounds of riding gear into each recommended range.

• 140 to 180 lb rider: Medium, 80 N/mm spring
• 180 to 220 lb rider: Heavy, 90 N/mm spring

Technical Information

• Architecture: Piggyback shock with steel spring
• Length: 289 mm
• Stroke: 78 mm
• Weight: 3.3 lb / 1.5 kg without spring
• Compression system: 2SC Two Stage Compression with independent high-speed and low-speed adjustment
• Low-speed compression: Tool-free adjustment, 18 clicks
• High-speed compression: 24 clicks, adjusted with a 20 mm hex
• Rebound: Tool-free adjustment, 24 clicks
• Spring adjustment: Adjustable preload
• Damping tune: Pro-level CMX Compact Motocross Tune
• Bottom-out system: MCU bumper
• Top-out system: Rubber bumper
• Seals: HNBR

Reservoir

The reservoir is designed around the large 16 mm shaft and its high oil-displacement requirements. An R46-spec internal floating piston system manages shaft displacement with precision, helping maintain a consistent damping feel during repeated hard impacts and high-heat riding.

Shaft

The R38 uses the same shaft as the larger R46. Its massive 16 mm induction heat-treated hollow shaft combines structural strength with increased oil flow through the main piston for true moto-level damping performance.

• Outside diameter: 16 mm
• Inside diameter: 5.5 mm
• Construction: Hollow, induction-hardened steel
• Finish: Hard chrome plated

Shock Body

A smaller-diameter body, spring, retainer, and hardware package reduces the shock’s external size while preserving the oversized internal flow characteristics responsible for its ride quality.

• Material: Seamless 6061 aluminum
• Finish: Type 3 hard anodized coating
• Thread: ACME

Main Piston

The 38 mm high-flow main piston uses true powersports architecture. It is slightly smaller than the R46 piston but follows the same high-flow design philosophy, providing a broad tuning range and consistent damping performance beyond typical shocks in this category.

• Diameter: 38 mm
• Material: CNC-machined 6061 billet aluminum
• Finish: Type 3 hard anodized coating
• Piston band: Hard band

Spring Retainer

• Material: Seamless 6061 aluminum
• Finish: Type 3 hard anodized coating
• Thread: ACME
• Adjustment: Manual preload adjustment with locking feature

Body Cap and Lower Eyelet

The upper body cap is engineered for tighter chassis fitment without sacrificing internal oil-flow performance. The new lower eyelet fits smaller bike platforms while maintaining maximum rebound oil flow to the shaft and metering rod.

• Body-cap bearing: Ultra-durable chrome-plated, Teflon-lined spherical bearing
• Lower-eyelet bearing: Ultra-durable chrome-plated, Teflon-lined spherical bearing

Fitment

• E-Ride Pro 3.0
• Requires the Prickly Motorsports R38-specific linkage, sold separately
• Not compatible with the stock E-Ride Pro lower linkage
• Designed to pair with Sirris F43 CMX forks
• Optional CMX fork drop clamp raises the front by 25 mm to match the rear height increase

Best Fit for These Riders

• Aggressive trail riders who need better heat management and damping consistency through repeated impacts
• Motocross-style riders looking for independent compression control, adjustable rebound, and stronger bottom-out support
• E-Ride Pro 3.0 owners building a balanced Sirris F43 CMX fork and R38 shock suspension package