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When a worn or undersized sprocket causes chain skip, vibration, or premature wear on your drive system, finding an exact-fit replacement becomes urgent. This 45# steel roller chain drive sprocket is designed for makers, hobbyists, and repair technicians who need a dependable, dimensionally accurate sprocket without sourcing from an OEM. Available in 9 through 14 tooth counts, it suits a wide range of speed-ratio requirements in compact drive assemblies.
Each sprocket is machined from 45# medium-carbon steel and finished with a black oxide coating for corrosion resistance. The stepped hub design accommodates bore diameters of 5 mm, 6 mm, 8 mm, 10 mm, and 12 mm (approximately 0.197"–0.472"), making it compatible with common motor and shaft sizes. The chain pitch is 1/4 inch (6.35 mm), matching standard #25 roller chain.
Typical use cases include go-kart and mini-bike drive trains requiring a 9–14T front sprocket, small conveyor systems where a compact stepped-hub sprocket simplifies shaft mounting, and DIY robotics or automation rigs that run #25 roller chain for precise torque transfer.
Machined from 45# steel for a balance of hardness and toughness, resisting deformation under cyclic chain loads in continuous-duty applications.
The black oxide surface treatment reduces surface friction and provides a baseline level of corrosion resistance suitable for indoor and sheltered outdoor environments.
The integrated stepped hub allows the sprocket to seat firmly against a shaft shoulder, reducing axial movement and simplifying alignment during assembly.
Six tooth-count options let you dial in the drive ratio for your specific speed and torque requirements without custom machining.
Five bore diameter options — 5 mm, 6 mm, 8 mm, 10 mm, and 12 mm — cover the most common motor output shaft and axle sizes used in small-scale drive systems.
Order 1, 2, 3, 5, or 10 pieces per transaction to match your project needs, whether you are replacing a single sprocket or stocking spares for a fleet of machines.
| Material | 45# Medium-Carbon Steel |
|---|---|
| Surface Finish | Black Oxide |
| Chain Pitch | 1/4 inch (6.35 mm) — #25 Roller Chain |
| Tooth Count Options | 9 T, 10 T, 11 T, 12 T, 13 T, 14 T |
| Bore Diameter Options | 5 mm, 6 mm, 8 mm, 10 mm, 12 mm |
| Hub Style | Stepped Hub |
| Outer Diameter | See variant options |
| Hub Length | See variant options |
| Weight (per piece) | See variant options |
| Pack Quantity Options | 1 Pcs, 2 Pcs, 3 Pcs, 5 Pcs, 10 Pcs |
The tooth count determines your drive ratio. Divide the driven sprocket's tooth count by the drive sprocket's tooth count to get the ratio. A lower tooth count on the drive sprocket increases torque at the output but reduces speed. For go-karts and mini-bikes, 9–11 T drive sprockets are common for higher top-end speed, while 12–14 T suits lower-speed, higher-torque setups.
Measure your motor output shaft or axle diameter with a caliper. Match it to the available bore options: 5 mm, 6 mm, 8 mm, 10 mm, or 12 mm. If your shaft falls between sizes, the bore can typically be enlarged by a machine shop, but it cannot be reduced. When in doubt, choose the bore that matches your shaft exactly.
Yes. This sprocket is designed for standard #25 roller chain with a 1/4 inch (6.35 mm) pitch. Verify that your existing chain is #25 before ordering. Using a mismatched chain pitch will cause rapid wear and potential chain derailment.
45# medium-carbon steel has a typical tensile strength of approximately 600–700 MPa after standard heat treatment, making it well-suited for moderate-load drive applications such as go-karts, small conveyors, and robotics. For very high-shock or heavy industrial loads, consider a hardened or alloy-steel sprocket instead.
Black oxide provides light corrosion resistance and is best suited for indoor or sheltered environments. For outdoor or wet conditions, apply a light coat of chain lubricant or anti-rust spray to the sprocket surface after installation. This significantly extends service life in humid or exposed environments.
The stepped hub creates a shoulder that the sprocket seats against on the shaft, preventing axial (side-to-side) movement during operation. This simplifies alignment, reduces the need for additional retaining hardware in many setups, and helps maintain consistent chain tension over time.
The bore is machined as a plain bore. Whether a set screw flat or keyway is present depends on the specific variant — please contact us to confirm before ordering if your application requires a keyed or set-screw bore. For plain-bore mounting, a shaft collar or retaining ring on the shaft is recommended to secure axial position.
