SRAM Eagle 90 Transmission E-MTB Crank Arm Assembly – Bosch (150mm / 155mm / 160mm / 165mm / 170mm)

The SRAM Eagle 90 Transmission E-MTB crank arm assembly is designed specifically for modern performance eMTBs—particularly riders looking for improved pedal clearance, cleaner drivetrain integration, and the ability to properly tune crank length to how they ride.

Built from forged aluminium, the Eagle 90 crank arms prioritise strength, durability, and reliability without unnecessary weight. SRAM positions this as a robust, dependable crank solution for aggressive trail, enduro, and eMTB riding where impact resistance matters just as much as aesthetics. SRAM lists the Bosch version at an engineering estimate of approximately 490g (based on 160mm with Bosch cap).

This Bosch version is designed around the ISIS spindle interface and is compatible with Bosch-equipped bikes, including Bosch CX BDU37 (Gen 4) and BDU38 (Gen 5) systems. It also uses SRAM’s removable Gap Cap system, creating a cleaner interface between the crank arm and motor while maintaining compatibility with other ISIS spindle-based motor systems where applicable.

The major advantage is crank length choice.

Available in:

• 150mm
• 155mm
• 160mm
• 165mm
• 170mm

This allows riders to properly optimise:

• pedal strike clearance
• cadence efficiency
• technical climbing
• descending stability
• rider balance on steep terrain

Modern eMTBs are increasingly moving toward shorter crank lengths, particularly 160mm and below, because the real-world improvement on technical terrain is immediately noticeable.

This isn’t just a replacement crank arm—it’s a genuine ride quality upgrade.

Key Features

• Forged aluminium crank arms for strength and durability
• Bosch-specific eMTB compatibility (including CX Gen4 / Gen5 systems)
• ISIS spindle interface
• Available in 150 / 155 / 160 / 165 / 170mm lengths
• Removable Gap Cap for cleaner integration and compatibility flexibility
• Black finish for clean OEM-style appearance
• Approx. weight: 490g (engineering estimate based on 160mm Bosch Cap)
• Designed for aggressive trail, enduro, and eMTB riding

Torque Collective Insight

This is one of the smartest upgrades for modern Bosch eMTBs.

Most riders still underestimate how much crank length changes ride feel.

Moving away from long cranks improves:

• pedal clearance
• technical climbing
• cornering confidence
• cadence efficiency
• rider balance on steep terrain

On bikes like:

• Orbea Wild
• Norco Range VLT
• YT Decoy
• Trek Rail
• Specialized Levo

…shorter cranks make a very noticeable difference.

This is why we stock these.

It’s not about replacing worn cranks—it’s about properly optimising how the bike rides.

For heavier, aggressive eMTB riding, forged alloy also makes far more sense than chasing fragile lightweight options.

This is a practical performance upgrade riders genuinely feel.

Fit & Sizing

Length Options

• 150mm
• 155mm
• 160mm
• 165mm
• 170mm

Compatibility

• Bosch-equipped eMTBs
• ISIS spindle interface
• Bosch CX Gen4 (BDU37)
• Bosch CX Gen5 (BDU38)

General Guidance

150–155mm

Best for:

• maximum pedal clearance
• very technical terrain
• aggressive descending
• riders prioritising clearance over leverage

160mm

Best all-round modern eMTB option:

• excellent clearance
• strong climbing position
• balanced cadence and leverage

165–170mm

Best for:

• riders preferring traditional feel
• flatter terrain
• more seated climbing leverage

For most aggressive eMTB riders, 160mm is the sweet spot.

Who It’s For

• Bosch eMTB riders
• Trail, enduro, and aggressive eMTB riders
• Riders wanting shorter cranks for performance gains
• Riders upgrading from 165/170mm crank arms
• Riders wanting premium OEM-level drivetrain integration

Who It’s Not For

• Non-Bosch bike owners (unless ISIS compatibility is confirmed)
• Lightweight XC riders prioritising minimal weight
• Riders wanting full cranksets with chainrings included