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When your drivetrain demands exact tooth engagement and consistent power transfer, a mismatched sprocket creates skipping, accelerated wear, and unexpected downtime. Makers, robotics builders, go-kart enthusiasts, and light industrial assemblers who rely on #25 roller chain need a sprocket machined to the correct pitch — not an approximation. These #25 chain drive sprockets are engineered specifically for #25 (04C) roller chain with a 1/4" (6.35mm) pitch, available in a wide tooth range from 9T to 80T to match your exact gear ratio requirement.
Each sprocket is machined from carbon steel with a natural or lightly finished surface. The bore diameter and hub dimensions vary by tooth count; refer to variant options for exact measurements. Tooth counts span 9T through 80T, covering a broad range of reduction ratios for both high-speed and high-torque applications. The 6.35mm pitch matches the ANSI #25 / ISO 04C chain standard precisely.
Typical use cases include small go-kart and mini-bike final drive assemblies, robotics and automation chain drive systems requiring compact #25 chain, conveyor and feeder mechanisms in light industrial or DIY workshop builds, and electric bicycle or motorized scooter reduction stages using #25 roller chain.
| Chain Standard | ANSI #25 / ISO 04C |
|---|---|
| Chain Pitch | 1/4" (6.35mm) |
| Tooth Count Range | 9T – 80T (select variant) |
| Material | Carbon Steel |
| Bore Diameter | See variant options |
| Hub Diameter | See variant options |
| Hub Length | See variant options |
| Outer Diameter | See variant options |
| Keyway | See variant options |
| Set Screw | See variant options |
| Surface Finish | Natural / Lightly Finished |
| Quantity per Order | 1 piece |
Your gear ratio is determined by dividing the driven sprocket tooth count by the drive sprocket tooth count. For example, a 9T drive sprocket paired with a 36T driven sprocket gives a 4:1 reduction. Lower tooth counts on the drive sprocket increase torque; higher tooth counts increase output speed. Select the tooth count that achieves your target ratio based on your motor RPM and desired output speed.
Yes. These sprockets are machined specifically for ANSI #25 and ISO 04C roller chain, both of which share a 1/4" (6.35mm) pitch. As long as your chain is a genuine #25 or 04C standard chain, the tooth profile and pitch will match correctly.
Bore diameter varies by tooth count. Please refer to the individual variant listing or contact us to confirm the bore size for your selected tooth count before ordering. We recommend verifying bore diameter against your shaft size to ensure a proper fit.
These carbon steel sprockets are suitable for light-to-medium duty applications including go-karts, mini bikes, and electric scooters running #25 chain. For sustained high-load or high-speed racing applications, verify the tooth count and bore size match your drivetrain requirements and inspect the sprocket regularly for wear.
Keyway and set screw availability varies by tooth count variant. Please select your specific tooth count above or contact us to confirm whether your chosen variant includes a keyway, set screw, or plain bore configuration.
Yes. ANSI #25 and ISO 04C are functionally equivalent standards — both use a 6.35mm (1/4") pitch. These sprockets are compatible with both designations. If your chain is labeled 04C, it will mesh correctly with these #25 sprockets.
Outer diameter increases with tooth count. For clearance-critical installations, contact us with your selected tooth count and we can provide the outer diameter measurement. As a general reference, a 9T #25 sprocket has an outer diameter of approximately 20–22mm (~0.8"), while an 80T sprocket will be significantly larger. Confirm dimensions before installation in tight enclosures.
