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When your go-kart, mini bike, motorized bicycle, or DIY conveyor project demands a reliable drive sprocket that won't slip, strip, or wobble under load, finding the right 04C sprocket with the exact bore size can be a frustrating search. These 04C roller chain drive sprockets are engineered for makers, hobbyists, and repair technicians who need a drop-in replacement or a purpose-built drive component that fits first time.
Each sprocket is machined from 45# medium-carbon steel, offering a solid balance of hardness and toughness for small-pitch chain drive applications. The tooth profile is cut to match the 1/4" (6.35mm) pitch of standard 04C roller chain. Tooth counts range from 8T to 30T, and bore diameters span 6mm to 15mm, covering the most common shaft sizes in this class. The M5 threaded set-screw hole locks the sprocket firmly onto the shaft without requiring a keyway.
Typical use cases include go-kart and mini-moto drive systems, small conveyor belt drives for DIY automation projects, and motorized bicycle or e-bike reduction stages — anywhere a compact, low-pitch chain drive sprocket is needed to transmit torque from a motor shaft to a driven axle.
Tooth geometry is cut to match the 6.35mm (1/4") pitch of standard 04C roller chain, ensuring smooth engagement and reduced chain wear over extended operation.
Machined from 45# medium-carbon steel for a reliable combination of surface hardness and core toughness — resists deformation under the cyclic loads typical of small-pitch chain drives.
Available in 8T through 30T tooth counts with bore options from 6mm to 15mm, covering the most common shaft diameters used in go-karts, mini bikes, and DIY conveyor systems.
An M5 threaded set-screw port secures the sprocket directly to the shaft without requiring a keyway, simplifying installation on smooth or lightly knurled shafts.
Dimensionally compatible with other standard 04C sprockets, making these a straightforward swap-in for worn or damaged sprockets on existing chain drive assemblies.
Each unit is sold as a single sprocket (or chain length where applicable). Select your exact tooth count and bore diameter from the Specification dropdown to receive the correct part.
| Chain Standard | 04C (1/4" pitch roller chain) |
|---|---|
| Pitch | 6.35mm (1/4") |
| Tooth Count (T) | 8T, 10T, 11T, 12T, 13T, 14T, 15T, 16T, 17T, 18T, 19T, 20T, 21T, 22T, 23T, 24T, 25T, 26T, 27T, 28T, 29T, 30T |
| Bore Diameter | 6mm, 8mm, 10mm, 12mm, 14mm, 15mm (see variant options) |
| Set-Screw Thread | M5 |
| Material | 45# medium-carbon steel |
| Surface Finish | See variant options |
| Hub Outer Diameter | See variant options |
| Overall Width | See variant options |
| Sold As | 1 piece per order (chain variants sold by length) |
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 10T drive sprocket paired with a 30T driven sprocket gives a 3:1 reduction — the output shaft turns at one-third the motor speed with three times the torque. For go-karts and mini bikes, common drive sprockets range from 10T to 18T depending on the desired top speed and motor RPM.
Measure your motor or axle shaft diameter with a caliper. The bore must match the shaft diameter exactly — a bore that is too large will allow the sprocket to wobble even with the set screw tightened. Available bores are 6mm, 8mm, 10mm, 12mm, 14mm, and 15mm. Select the bore that matches your shaft from the Specification dropdown.
These sprockets are designed for standard 04C roller chain with a 6.35mm (1/4") pitch. This is also commonly labeled as 25H chain in some markets. Do not use with 08B, 40, or other pitch chains — the tooth profile will not mesh correctly and will cause rapid wear or chain skipping. Matching 1/2" roller chain lengths are also available as a separate variant in the Specification dropdown.
45# steel (equivalent to SAE 1045 carbon steel) is a widely used engineering material for sprockets and gears in light-to-medium duty applications. It offers a tensile strength typically in the range of 600–800 MPa depending on heat treatment, which is well-suited for the torque loads encountered in go-karts, mini bikes, and small conveyor systems. For heavy industrial applications with continuous high-load cycling, hardened or alloy steel sprockets would be more appropriate.
45# carbon steel will oxidize if left unprotected in humid or wet environments. For outdoor or damp applications, apply a light coat of chain lubricant or anti-rust spray to both the sprocket and chain. If corrosion resistance is a primary requirement, consider stainless steel sprockets instead. Regular lubrication of the chain drive will significantly extend the service life of both the chain and sprocket.
No keyway is required. The M5 set screw clamps directly against the shaft surface. For best holding power on smooth shafts, ensure the set screw is tightened firmly with the correct hex key (typically 3mm or 4mm). For applications with high shock loads or frequent direction reversals, a flat ground onto the shaft at the set-screw contact point will improve retention significantly.
Yes. 04C sprockets are commonly used in motorized bicycle friction drive systems and small mid-drive reduction stages where a compact chain pitch is needed. Verify that your existing chain is 04C / 1/4" pitch and that the shaft diameter matches your selected bore before ordering. The tooth count you need will depend on your motor's output shaft size and your target gear ratio.
