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When your chain drive slips, wears unevenly, or simply won't fit the shaft you have on hand, the problem is almost always a mismatched sprocket. Makers, robotics builders, go-kart enthusiasts, and light industrial DIYers who work with #25 (04C) roller chain need a sprocket that locks firmly to the shaft, transfers torque without play, and holds its geometry under load — this #25 roller chain sprocket with keyway bore is engineered for exactly that.
Each sprocket is machined from carbon steel and features a precision-cut keyway bore for positive shaft engagement. Tooth counts range from 13T to 40T, and bore diameters span 8 mm (0.31 in) to 30 mm (1.18 in), with keyway widths from 3×1.4 mm up to 8×3.3 mm depending on bore size. The chain pitch is 6.35 mm (0.25 in), fully compatible with ANSI #25 and DIN 04C roller chain.
Typical use cases include #25 chain drive speed reduction for electric go-karts and mini bikes, sprocket replacement in conveyor and feeder mechanisms, and custom gear ratio builds for robotics and automation projects requiring a keyed shaft sprocket with precise tooth count selection.
Available from 13T to 40T, covering a broad spectrum of gear ratios for speed reduction or torque multiplication in #25 chain drive systems.
Each sprocket includes a machined keyway slot — from 3×1.4 mm to 8×3.3 mm depending on bore size — eliminating shaft slip under torque load.
Bore options span 8 mm to 30 mm (0.31–1.18 in), with K-Type and standard keyway configurations available to match common shaft standards.
Machined from carbon steel for durability in mechanical drive applications, with tooth geometry matched to ANSI #25 / 04C chain pitch of 6.35 mm.
Tooth form is cut to match #25 roller chain engagement geometry, reducing chain wear and maintaining consistent pitch contact across the full tooth count range.
Dimensionally compatible with standard #25 chain sprocket applications — suitable for go-karts, conveyors, robotics, and light machinery requiring a keyed shaft sprocket.
| Chain Standard | ANSI #25 / DIN 04C |
|---|---|
| Chain Pitch | 6.35 mm (0.25 in / 1/4 in) |
| Tooth Count | 13T – 40T (see variant options) |
| Bore Diameter | 8 mm – 30 mm (see variant options) |
| Keyway Width × Depth | 3×1.4 mm / 4×1.8 mm / 5×2.3 mm / 6×2.8 mm / 8×3.3 mm (varies by bore) |
| Keyway Type | Standard and K-Type (see variant options) |
| Material | Carbon Steel |
| Finish | See variant options |
| Hub Style | See variant options |
| Quantity per Order | 1 piece |
| Weight | 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 13T driver paired with a 40T driven sprocket gives approximately a 3:1 reduction. Select a tooth count that achieves your target speed or torque output based on your motor RPM and load requirements.
K-Type keyways follow a specific dimensional standard where the keyway depth is proportionally shallower relative to the bore diameter compared to standard DIN/ANSI keyways. Both types lock the sprocket to the shaft using a key, but they are not interchangeable — match the keyway type to your shaft's existing keyway cut. If your shaft has a standard keyway, select a standard bore variant; if it has a K-Type cut, select the K-Type variant.
Yes. This sprocket is designed for ANSI #25 / DIN 04C roller chain with a pitch of 6.35 mm (1/4 in). As long as your chain matches this pitch standard, the sprocket tooth profile will engage correctly. Verify your chain's pitch marking — #25 or 04C — before ordering.
Measure your shaft diameter with a caliper. Select the bore size that matches your shaft diameter exactly — the bore is machined to close tolerance. The keyway width must also match the key already cut into your shaft. Available bore sizes range from 8 mm to 30 mm; refer to the variant selector above for all available combinations of tooth count and bore.
#25 chain is commonly used on small go-karts, mini bikes, and electric scooters where the power and speed requirements fall within the chain's rated load capacity. This sprocket is compatible with those applications. Confirm that your drive system's torque and speed ratings are within the limits of #25 chain before use in high-load or high-speed applications.
Yes. Keyed bore sprockets are standard in conveyor, feeder, and light automation applications where the sprocket must be positively locked to a driven shaft. Ensure the bore and keyway dimensions match your shaft and that the tooth count gives you the correct chain speed for your conveyor's throughput requirements.
The sprocket is machined from carbon steel, which provides good strength and wear resistance for mechanical drive use. Carbon steel is not inherently corrosion-resistant — in humid or wet environments, apply a light machine oil or anti-rust coating to exposed surfaces. For corrosive environments, contact us to confirm material options.
