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When a worn or mismatched sprocket causes chain skip, premature wear, or unexpected downtime, finding a direct-fit replacement in the right tooth count becomes critical. This #40 roller chain sprocket is engineered for makers, machine builders, and mechanical hobbyists who need a reliable, dimensionally accurate drive component without custom machining lead times.
Each sprocket is machined from C45 medium-carbon steel, offering a solid balance of hardness and machinability. The rough bore design allows you to bore and key the hub to your exact shaft size. Available in tooth counts from 10T to 39T with rough bore diameters ranging from 10mm to 16mm (approximately 0.39" to 0.63"), these sprockets are sized to match standard ANSI #40 / ISO 08B roller chain with a 1/2" (12.7mm) pitch. A 1.5-meter roller chain section, standard chain links, and half links are also available as companion variants.
Typical applications include go-kart and mini-bike drive systems requiring a #40 chain sprocket replacement, conveyor and automation builds using 12.7mm pitch roller chain, and DIY power transmission projects such as electric bike conversions, winches, and small engine drives where a C45 steel sprocket with rough bore provides the flexibility to fit custom shaft diameters.
Available from 10T to 39T, covering a broad gear ratio spectrum for speed reduction or torque multiplication in custom drive systems.
Supplied with a rough bore (10mm, 12mm, 14mm, or 16mm) so you can bore, ream, and key the hub to match your exact shaft diameter without starting from solid stock.
Machined from C45 steel for a reliable combination of surface hardness, wear resistance, and ease of secondary machining operations.
Dimensioned to the 12.7mm pitch standard, ensuring direct interchangeability with any ANSI #40 or ISO 08B roller chain on the market.
Companion variants include a 1.5-meter #40 roller chain section, standard chain links, and half links — so you can source the complete drive assembly in one order.
Suited for go-karts, mini-bikes, conveyor systems, electric bike conversions, and small engine power transmission projects where dimensional accuracy matters.
| Chain Standard | ANSI #40 / ISO 08B |
|---|---|
| Chain Pitch | 1/2" (12.7mm) |
| Tooth Count Options | 10T, 11T, 12T, 13T, 14T, 15T, 16T, 17T, 18T, 19T, 20T, 21T, 22T, 23T, 24T, 25T, 26T, 27T, 28T, 29T, 30T, 31T, 32T, 33T, 34T, 35T, 36T, 37T, 38T, 39T |
| Rough Bore Diameter | 10mm, 12mm, 14mm, 16mm (varies by tooth count — see variant options) |
| Material | C45 Medium-Carbon Steel |
| Bore Type | Rough Bore (requires secondary machining to final shaft size) |
| Hub Style | See variant options |
| Outer Diameter | See variant options |
| Hub Length | See variant options |
| Surface Finish | See variant options |
| Quantity per Order | 1 pcs (standard); 1.5m chain section also available |
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 — tripling torque while reducing speed by two-thirds. Select a tooth count that achieves your target speed or torque output based on your motor RPM and load requirements.
A rough bore sprocket is supplied with a smaller-than-final bore diameter. You (or a machine shop) bore, ream, and optionally cut a keyway to match your exact shaft size. The listed rough bore diameter (10mm, 12mm, 14mm, or 16mm) is the starting bore — your final shaft diameter must be equal to or smaller than this value. If your shaft is 15mm, select the 16mm rough bore variant.
Yes — these sprockets are machined to the ANSI #40 / ISO 08B standard with a 1/2" (12.7mm) pitch. They are dimensionally interchangeable with any standard #40 roller chain. Confirm your chain's pitch marking (usually stamped on the side plate) before ordering. Do not use with #35, #50, or other pitch chains.
C45 is a medium-carbon steel with a tensile strength typically in the range of 570–700 MPa in the normalized condition, and higher after heat treatment. It provides good wear resistance for light-to-medium duty power transmission applications such as go-karts, conveyors, and small engine drives. For heavy industrial or high-shock-load applications, consider a hardened or alloy steel sprocket.
C45 steel is not stainless and will oxidize if left unprotected in humid or wet environments. For outdoor or wash-down applications, apply a chain lubricant or anti-corrosion coating after installation. Regular lubrication of both the chain and sprocket teeth is recommended to extend service life and prevent surface rust.
Yes. This listing includes companion variants: a 1.5-meter #40 roller chain section, a standard chain link (connecting link), and a half link for fine-tuning chain length. Select the appropriate variant from the options above to add them to your order alongside the sprocket.
The available rough bore diameter increases with tooth count to accommodate the larger hub geometry. As a general guide: 10T–11T are available with 10mm bore; 12T–20T with 12mm bore; 21T–29T with 14mm bore; 30T–39T with 16mm bore. Always verify the specific variant listing before ordering, as bore availability may vary.
