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When a worn or mismatched sprocket causes chain skip, vibration, or premature wear on your drive system, finding an exact-spec replacement becomes critical. These 04C roller chain sprockets are engineered for makers, repair technicians, and machine builders who need reliable, dimensionally accurate components without sourcing delays.
Each sprocket is machined to suit the 04C (1/4" / 6.35mm pitch) roller chain standard. Available in tooth counts from 9T to 24T and bore sizes ranging from 5mm to 20mm (~0.197" to ~0.787"), with hub types including Through Hole, Keyway, and D Hole configurations. Material is carbon steel with a natural or lightly finished surface typical of precision-machined drive components.
Typical applications include small conveyor drives, robotics and automation platforms, go-kart and mini-bike reduction drives, and compact power transmission assemblies where a 04C roller chain sprocket replacement or custom drive ratio is required.
Dimensionally matched to 04C roller chain (6.35mm pitch), ensuring correct engagement and minimal chain wear across the full tooth range.
Choose from Through Hole (plain bore), Keyway (with keyway slot for positive shaft locking), or D Hole (flat-sided bore for set-screw retention) to match your shaft interface.
Covers a broad gear ratio spectrum for speed reduction or increase in compact drive systems, from 9-tooth pinion sprockets to 24-tooth driven sprockets.
Accommodates common shaft diameters from 5mm to 20mm (~3/16" to ~25/32"), including fractional sizes like 6.35mm (1/4") for imperial shaft compatibility.
Machined from carbon steel for adequate strength in light-to-medium duty drive applications, with tooth profiles ground to 04C chain roller geometry.
Select variants include slotted bores for fine shaft-fit adjustment, and keyway variants specify key dimensions (e.g., 3×1.4mm, 4×1.8mm, 5×2.3mm, 6×2.8mm) for direct specification matching.
| Chain Standard | 04C / #25 |
|---|---|
| Chain Pitch | 6.35mm (1/4") |
| Roller Diameter | 3.97mm (5/32") — standard 04C |
| Tooth Count Range | 9T, 10T, 11T, 12T, 13T, 14T, 15T, 16T, 17T, 18T, 19T, 20T, 21T, 22T, 23T, 24T |
| Bore Range | 5mm – 20mm (see variant options) |
| Hub Types | Through Hole / Keyway / D Hole |
| Keyway Dimensions | See variant options (3×1.4mm / 4×1.8mm / 5×2.3mm / 6×2.8mm) |
| Material | Carbon Steel |
| Surface Finish | See variant options |
| Outer Diameter | See variant options |
| Hub Length | See variant options |
| Weight | See variant options |
The tooth count determines your drive ratio. Divide the driven sprocket teeth by the drive sprocket teeth to get the reduction ratio. For example, a 9T drive sprocket paired with an 18T driven sprocket gives a 2:1 reduction. Higher tooth counts on the driven side reduce output speed and increase torque.
Through Hole is a plain round bore — typically secured with a set screw or press fit. Keyway bore includes a machined slot that accepts a key for positive rotational locking, preventing slippage under load. D Hole has one flat side matching a D-profile shaft, commonly used with motor output shafts in robotics and small drives.
These sprockets are designed for 04C roller chain, also known as #25 chain, with a 6.35mm (1/4") pitch and approximately 3.97mm roller diameter. Do not use with 25H (heavy) chain or other pitch standards without verifying compatibility.
Measure your shaft diameter precisely with calipers. Select the bore size that matches your shaft — for a sliding fit, the bore should be equal to or very slightly larger than the shaft. For keyway variants, also confirm the key dimensions (width × height) match your shaft's keyway slot.
These carbon steel 04C sprockets are suited for light-to-medium duty applications such as robotics, small conveyors, go-karts, and hobby machinery. For continuous high-speed or heavy industrial use, verify load ratings against your application requirements and consider lubrication of the chain drive.
A slotted bore has a narrow radial slot cut through the hub, allowing the bore to be slightly compressed with a clamping bolt for a secure grip on the shaft. This provides adjustability and a firm hold without requiring a precise interference fit, making it useful when shaft diameter tolerances vary.
No. While 25H chain shares the same 6.35mm pitch as 04C/25 chain, the 25H chain has a heavier plate thickness. The sprocket tooth profile is the same, so engagement is possible, but 25H chain is rated for higher loads and is typically used with sprockets specified for that chain series. Confirm compatibility with your chain supplier before mixing standards.
