The Shimano Nexus SG-3D55 is a 3-speed internally geared rear hub designed for city, commuter and urban trekking bikes. With all gear internals sealed inside the aluminium shell, it delivers reliable low-maintenance gearing paired with a Centre Lock disc brake interface — making it ideal for all-weather riders who want clean, dependable performance without derailleur complexity.

Highlights

• 3-speed internal gearing: 186% gear range covers flat urban terrain and moderate gradients with 1st (0.733), 2nd (direct drive, 1.00) and 3rd (1.36) ratios.
• Centre Lock disc interface: Spline-mount rotor attachment allows fast, precise rotor installation and removal while enhancing braking rigidity and efficiency.
• Silent clutch mechanism: Smooth, quiet gear engagement typical of Shimano Nexus internals — reliable shift after shift in commuter conditions.
• Aluminium hub shell: Lightweight yet durable alloy construction keeps rotational weight low.
• 36-hole lacing: Higher spoke count supports heavier loads and builds a more robust, durable wheel suited to racks and panniers.
• All-weather sealed internals: Gear mechanism fully enclosed — protected from rain, dust and road grime with minimal servicing required.

Design & Construction

The SG-3D55 uses a loose ball bearing system housed in an aluminium shell with a solid 3/8" threaded bolt-on axle. The internal 3-speed mechanism uses a planetary gear set to deliver a 186% gear range — enough spread for urban stop-start riding and gentle hills. The Centre Lock rotor mount (rotor not included) secures via a spline interface and lock ring, ensuring consistent braking power across all three gears. The hub ships in black.

Compatibility & Fit

Axle: 3/8" threaded, 135mm over locknut distance (OLD). Spoke count: 36 holes, J-bend interface, maximum spoke gauge 13g (2.34mm). Disc mount: Shimano Centre Lock (6-bolt rotors require an adapter). Requires a compatible Shimano Nexus 3-speed shifter and bell crank (sold separately). Designed for urban/trekking use on paved and light gravel surfaces — not intended for off-road riding or heavy climbing out of the saddle. Recommended sprocket ratio: 2.0–2.65:1. Compatible with Shimano Nexus Inter-3 drivetrain components.