Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.
When a worn or undersized sprocket causes chain skip, vibration, or premature wear on your 04C roller chain drive, the fix starts with a correctly sized pilot bore sprocket. Makers, machine builders, and mechanical hobbyists who need a reliable, drop-in sprocket for compact 04C chain drives rely on a part that holds tight tolerances and mounts cleanly to a custom-bored shaft.
These 04C pilot bore sprockets are machined from carbon steel with a natural or black oxide finish depending on the selected variant. The pilot bore is left unfinished so you can bore and key it to your exact shaft diameter. Tooth counts range from 32T to 40T (04C 32T, 33T, 35T, 36T, 38T, 40T), and bore options span 8 mm to 30 mm (approximately 0.31 in to 1.18 in), covering a wide range of shaft sizes. Keyway dimensions vary by bore size — typically 5×2.3 mm for mid-range bores and 6×2.8 mm or 8×3.3 mm for larger bores.
Typical use cases include small conveyor drives requiring a 04C sprocket replacement, DIY go-kart or mini-bike chain drive builds needing a custom-bored 04C 35T sprocket, and light industrial automation projects where a compact roller chain sprocket with a pilot bore simplifies shaft fitment. Available in 1 pc, 3 pc, and 5 pc quantities to suit prototyping or small-batch production runs.
| Chain Standard | 04C (25H), Pitch 6.35 mm (1/4 in) |
|---|---|
| Tooth Count | 32T, 33T, 35T, 36T, 38T, 40T (see variant options) |
| Bore Diameter | 8 mm – 30 mm (0.31 in – 1.18 in) (see variant options) |
| Keyway Dimensions | 5×2.3 mm / 6×2.8 mm / 8×3.3 mm (varies by bore size) |
| Material | Carbon Steel |
| Finish | Natural Steel or Black Oxide (see variant options) |
| Hub Style | Pilot Bore (unfinished, ready for custom machining) |
| Outer Diameter | See variant options |
| Hub Diameter | See variant options |
| Hub Length | See variant options |
| Weight | See variant options |
| Quantity per Order | 1 pc / 3 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 ratio. For example, a 32T driven sprocket paired with a 16T driver gives a 2:1 reduction. Choose a tooth count that achieves your target speed or torque ratio. Available options are 32T, 33T, 35T, 36T, 38T, and 40T.
A pilot bore sprocket ships with a small, unfinished center hole. You or a machine shop bores it out to your exact shaft diameter and cuts a keyway to match your shaft. This gives you a precise, custom fit that a fixed-bore sprocket cannot provide. Select the bore size closest to — but not larger than — your shaft diameter before machining.
Choose a bore option that is equal to or slightly larger than your shaft diameter. The listed bore sizes (8 mm to 30 mm) represent the finished hole diameter after machining. If your shaft is 12 mm, select the Hole 12 mm variant. For shafts requiring a keyway, check that the keyway dimensions (5×2.3 mm, 6×2.8 mm, or 8×3.3 mm) match your shaft's keyway spec.
Yes. 04C and 25H are two designations for the same chain standard — both have a 6.35 mm (1/4 in) pitch. These sprockets are fully compatible with 04C / 25H roller chain. Confirm your chain pitch before ordering to ensure compatibility.
Standard variants have a natural carbon steel finish. Black variants feature a black oxide surface treatment that provides a modest improvement in corrosion resistance for light-duty or indoor environments. Both variants are made from the same carbon steel and have identical dimensional specifications. Choose Black if aesthetics or mild corrosion resistance matter for your application.
Yes, provided your drive uses 04C (25H) roller chain. These sprockets are commonly used in small vehicle builds, DIY go-karts, and mini-bikes where compact chain drives are required. Verify the tooth count matches your desired gear ratio and that the bore size suits your axle or jackshaft diameter before machining.
Ordering 3 or 5 pieces at once reduces per-unit cost and ensures you have spares on hand for maintenance or multi-sprocket drive systems. The 5 pc option is particularly useful for production builds or conveyor systems that use several identical sprockets.
