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When a worn or undersized sprocket causes chain skip, vibration, or premature wear in your drive system, finding an exact-spec replacement is critical. These 04C 25H roller chain sprockets are engineered for makers, machine builders, and repair technicians who need a dependable, dimensionally accurate component for #25 (1/4" pitch) chain drives.
Each sprocket is machined from 45# medium-carbon steel, offering a solid balance of hardness and machinability. The body is 15mm (approximately 0.59") thick, with tooth counts ranging from 9T to 30T and bore sizes from 5mm to 16mm to suit a wide range of shaft diameters. The 25H designation indicates a hub-style body with a standard keyway-ready bore.
Typical applications include small conveyor drives, go-kart and mini-bike transmissions, robotics and automation rigs, and light industrial machinery using #25 roller chain. Whether you are replacing a failed sprocket on a chain-driven actuator or building a custom reduction drive for a CNC project, these sprockets deliver consistent tooth engagement and long service life.
| Chain Standard | ANSI #25 / ISO 04C |
|---|---|
| Chain Pitch | 6.35mm (1/4") |
| Tooth Count Range | 9T – 30T (see variant options) |
| Bore Size Range | 5mm, 6mm, 8mm, 10mm, 12mm, 14mm, 15mm, 16mm |
| Body Thickness | 15mm (approx. 0.59") |
| Material | 45# Medium-Carbon Steel |
| Hub Style | 25H (hub with keyway-ready bore) |
| Finish | See variant options |
| Quantity per Order | 1 pc or 5 pcs (see variant options) |
The tooth count determines your drive ratio. Divide the driven sprocket teeth by the driver sprocket teeth to get the reduction ratio. For example, a 9T driver paired with a 27T driven sprocket gives a 3:1 reduction. Match the tooth count to your existing sprocket or calculate based on your target output speed.
Measure your shaft diameter with a caliper and select the matching bore size. Available bores are 5mm, 6mm, 8mm, 10mm, 12mm, 14mm, 15mm, and 16mm. If you plan to add a keyway or set screw, confirm the hub wall thickness is sufficient for your shaft size before machining.
Yes. These sprockets are designed for ANSI #25 / ISO 04C roller chain with a 6.35mm (1/4") pitch. They are not compatible with #35, #40, or other chain sizes. Always verify the chain pitch matches before installation.
45# medium-carbon steel has a tensile strength typically in the range of 600–800 MPa, making it well-suited for moderate-load chain drive applications such as conveyors, go-karts, and light machinery. For heavy shock loads or corrosive environments, consider additional surface treatment or a different material grade.
45# steel provides moderate corrosion resistance in dry indoor environments. For outdoor or humid applications, applying a rust-inhibiting lubricant or coating is recommended. If corrosion resistance is a primary requirement, consider stainless steel sprockets instead.
Yes. These sprockets function in horizontal, vertical, and inclined chain drive configurations. Ensure proper chain tension and lubrication regardless of orientation. Vertical drives may require more frequent tension checks as chain sag behaves differently under gravity.
The bore is supplied as a finished round bore. If your application requires a keyway, set screw hole, or custom bore diameter, you will need to machine these features yourself or have them done by a local machine shop. The 45# steel material machines cleanly with standard tooling.
