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When a worn or mismatched sprocket causes chain skip, noise, or premature wear, the entire drivetrain suffers — and so does your project timeline. Whether you're a maker building a go-kart, a hobbyist assembling a conveyor, or a technician replacing a drive component, you need a sprocket machined to tight tolerances that meshes cleanly with your #25 roller chain from the very first revolution.
This #25 04C roller chain sprocket is machined from 45# medium-carbon steel, offering a solid balance of hardness and toughness for demanding drive applications. The bore and hub dimensions vary by tooth count; the pitch is a fixed 6.35mm (1/4 in) across the full 8T–80T range, with sprocket outer diameters scaling from approximately 18mm (0.71 in) at 8 teeth to roughly 163mm (6.42 in) at 80 teeth. Roller chain compatibility is #25 / 04C (pitch 6.35mm, roller diameter 3.30mm).
Typical use cases include small go-kart and mini-bike final drives where a compact #25 chain sprocket keeps weight low, light-duty conveyor and indexing systems requiring precise tooth engagement, and DIY automation rigs — such as CNC axis drives or robotic arm joints — where a 6.35mm pitch roller chain sprocket delivers repeatable positioning without backlash.
| Chain Standard | #25 / 04C |
|---|---|
| Pitch | 6.35 mm (1/4 in) |
| Roller Diameter | 3.30 mm (0.130 in) |
| Tooth Count Range | 8T – 80T (see variant options) |
| Material | 45# Medium-Carbon Steel |
| Outer Diameter | See variant options |
| Bore Diameter | See variant options |
| Hub Style | See variant options |
| Finish | Natural / uncoated machined steel |
| Applicable Model | #25 04C — Sprocket |
| Connecting Links | #25 04C Full Buckle (5 PCS) / Half Buckle (1 PCS) — available as Model option |
| Roller Chain Option | #25 04C Roller Chain — 0.5m, 1.5m, 5m, 10m lengths available |
Tooth count determines your drive ratio. Divide the driven sprocket teeth by the driver sprocket teeth to get the ratio — for example, a 10T driver paired with a 30T driven sprocket gives a 3:1 reduction. Higher tooth counts on the driven side increase torque and reduce output speed; lower counts do the opposite. For go-karts and mini-bikes, common driver sprockets range from 8T–12T; for conveyors, match the ratio to your required belt speed.
Yes. #25 and 04C are two designations for the same chain standard: 6.35mm (1/4") pitch with a 3.30mm roller diameter. This sprocket is machined to that pitch, so it meshes correctly with any #25 or 04C roller chain meeting ANSI or ISO standards. The matching roller chain and connecting links are also available as Model options in this listing.
45# medium-carbon steel typically achieves a tensile strength of 600–800 MPa in the normalized or quenched-and-tempered condition, with a surface hardness in the HRC 20–35 range depending on heat treatment. For #25 chain drives — which have a rated breaking load of approximately 3.5 kN — this material provides a substantial safety margin under normal operating loads. For high-cycle or high-shock applications, consider whether additional surface hardening is appropriate for your specific duty cycle.
45# steel is not inherently corrosion-resistant. In outdoor, humid, or wet environments, surface oxidation will occur over time. To extend service life, apply a light machine oil or chain lubricant to both the sprocket teeth and the roller chain regularly. For applications requiring higher corrosion resistance, consider pairing with a stainless-steel #25 chain and applying a protective coating to the sprocket, or contact us to discuss alternative material options.
Bore diameter varies by tooth count and is listed under the variant specifications. Many tooth-count variants ship with a pilot bore that can be machined to a custom diameter by a local machine shop to fit your shaft. If you need a specific bore size confirmed before ordering, please use the Contact Us page with your tooth count and required bore diameter.
Yes — this listing covers the complete #25 04C drivetrain. Use the Model selector to choose between the Sprocket (8T–80T), Roller Chain (0.5m, 1.5m, 5m, or 10m lengths), Full Buckle connecting links (pack of 5), or Half Buckle connecting links (single piece). Adding all required components from this one listing simplifies ordering and ensures chain-to-sprocket compatibility.
A common formula for chain length in links is: L = 2C/P + (T1 + T2)/2 + (T2 − T1)²/(4π²C/P), where C is center distance, P is pitch (6.35mm), T1 is driver teeth, and T2 is driven teeth. Round up to the nearest even number of links, then add one connecting link. For most small drives with center distances under 300mm, a 0.5m or 1.5m chain length is sufficient; larger conveyor runs may require the 5m or 10m option.
