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When a worn or undersized sprocket causes chain skip, uneven wear, or unexpected downtime on your small-scale drive system, finding an exact-fit replacement in the right tooth count and bore diameter is the real challenge. These 04C roller chain sprockets are designed for engineers, hobbyists, and repair technicians who need a reliable, dimensionally accurate drive component without sourcing from an industrial distributor.
Each sprocket is machined from 45# medium-carbon steel and engineered to the 04C (1/4" pitch, 6.35 mm) roller chain standard. Tooth counts span 31T through 70T, with bore diameters available from 8 mm (0.31 in) to 15 mm (0.59 in). The product line also includes matching 1/4" roller chain by the metre and individual chain links for complete drivetrain builds or repairs.
Typical applications include small conveyor drives, go-kart and mini-bike reduction stages, robotics and automation platforms, and compact agricultural or garden equipment where 04C chain is the specified drive standard. Long-tail use cases such as "04C sprocket replacement for mini conveyor" or "1/4 pitch chain sprocket 40 tooth 10mm bore" are covered across the full variant matrix.
| Chain Standard | 04C / #25 Roller Chain |
|---|---|
| Pitch | 1/4" (6.35 mm) |
| Tooth Count Range | 31T – 70T (see variant options) |
| Bore Diameter | 8 mm / 10 mm / 12 mm / 14 mm / 15 mm (see variant options) |
| Material | 45# Medium-Carbon Steel |
| Surface Finish | See variant options |
| Hub Style | See variant options |
| Keyway | See variant options |
| Set Screw | See variant options |
| Chain Link Type | 04C / 1/4" (available as add-on variant) |
| Roller Chain Lengths | 0.5 m, 1.5 m, 5 m, 10 m (available as add-on variant) |
| Amount per Order | 1 pcs / 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 40T driven sprocket paired with a 20T driver gives a 2:1 reduction — the output shaft turns at half the input speed with twice the torque. Select a tooth count that achieves your target ratio while keeping chain wrap angle above 120° on the smaller sprocket.
Use a digital caliper to measure the outer diameter of your shaft at the mounting point. Available bore sizes are 8 mm, 10 mm, 12 mm, 14 mm, and 15 mm. The bore should match your shaft diameter exactly — a loose fit will cause vibration and accelerated wear. If your shaft requires a keyway or set screw, confirm those details in the variant options before ordering.
45# medium-carbon steel has a tensile strength of approximately 600–800 MPa in its normalized state, making it suitable for moderate-duty cyclic drive loads typical of small conveyors, go-karts, and robotics. For heavy shock loads or continuous high-speed industrial duty, consider whether a hardened or alloy-steel sprocket is more appropriate for your specific application.
45# steel without additional surface treatment will oxidize in humid or wet conditions. For outdoor or damp environments, apply a chain lubricant regularly and consider a protective coating such as zinc plating or paint. If corrosion resistance is a primary requirement, evaluate stainless-steel sprocket alternatives for your application.
Yes. The 04C designation and the ANSI #25 designation both refer to roller chain with a 1/4" (6.35 mm) pitch. These sprockets are dimensionally compatible with both designations. Always verify the roller diameter and inner link width of your existing chain against the sprocket tooth profile if you are mixing chain brands.
Yes. This listing includes 1/4" roller chain sold by length (0.5 m, 1.5 m, 5 m, and 10 m) as well as individual 04C chain links (5-piece packs) and half-chain links. Select the appropriate option from the "Number of Teeth" dropdown — chain and link variants are listed alongside the sprocket tooth-count options.
Use the standard chain length formula: L = 2C + (T₁ + T₂)/2 + (T₂ − T₁)²/(4π²C), where C is the center distance in pitches, T₁ is the small sprocket tooth count, and T₂ is the large sprocket tooth count. Round up to the nearest even link count. Add 10–15% extra when ordering chain by the metre to allow for trimming and future re-tensioning.
