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When your small-scale drivetrain demands exact tooth engagement and zero slop, a mismatched sprocket becomes the weakest link in the system. Makers, robotics builders, and automation hobbyists working with #25 roller chain need a sprocket that holds tight tolerances across every bore size — whether you're mounting to a 5mm motor shaft or a 6.35mm (1/4") keyed axle.
This #25 chain sprocket features 9 teeth and a 6.35mm pitch, machined to match ANSI #25 roller chain geometry. The hub is available in four bore diameters — 5mm, 6mm, 6.35mm, and 8mm — spanning approximately 5–8mm (0.197"–0.315"). The sprocket body is constructed from carbon steel with a natural or lightly treated finish, offering solid wear resistance for indoor and light-duty outdoor drive applications.
Typical use cases include small conveyor drives, robotics joint actuators, go-kart throttle linkages, and DIY chain-drive transmission builds where a compact 9-tooth sprocket keeps the drive ratio tight and the package size minimal. The #25 chain sprocket 9T is also a go-to for educators and prototypers building chain-drive demonstration rigs or iterating on custom gearbox designs.
Tooth profile and pitch (6.35mm) are machined to ANSI #25 roller chain specifications, ensuring smooth engagement and consistent chain wrap across the 9-tooth count.
Choose from 5mm, 6mm, 6.35mm (1/4"), or 8mm bore to match your motor shaft, axle, or drive rod — no adapter sleeve required for standard shaft sizes.
The sprocket body is made from carbon steel, delivering the hardness and wear resistance needed for sustained chain contact under moderate load cycles.
Available in packs of 1, 2, 5, 10, 25, or 50 pieces — order a single unit for prototyping or stock up in bulk for production runs and repair inventory.
A 9-tooth driver sprocket enables high reduction ratios when paired with a larger driven sprocket, making it ideal for torque-multiplying applications in small robotics and automation.
Dimensionally consistent with standard #25 sprocket hubs — fits existing chain drive assemblies without modification to chain length or frame geometry in most applications.
| Chain Standard | ANSI #25 |
|---|---|
| Number of Teeth | 9T |
| Chain Pitch | 6.35mm (1/4") |
| Bore Diameter Options | 5mm / 6mm / 6.35mm / 8mm |
| Material | Carbon Steel |
| Finish | See variant options |
| Hub Style | See variant options |
| Setscrew / Keyway | See variant options |
| Pitch Diameter (approx.) | Typically 18–20mm (0.71"–0.79") |
| Outside Diameter (approx.) | Typically 20–23mm (0.79"–0.91") |
| Hub Length (approx.) | See variant options |
| Available Quantities | 1 / 2 / 5 / 10 / 25 / 50 pcs |
Measure the outer diameter of your motor shaft or axle with a caliper. Match that measurement to the available bore options: 5mm, 6mm, 6.35mm (1/4"), or 8mm. If your shaft is slightly undersized, a setscrew or keyway can compensate — check your hub style before ordering.
This sprocket is designed for standard ANSI #25 roller chain with a 6.35mm pitch. #25H chain shares the same pitch but has thicker side plates. The tooth profile will engage correctly, but verify your chain's roller diameter matches the sprocket's tooth gap before running under load.
As a carbon steel #25 sprocket, it is suited for light-to-moderate duty applications. ANSI #25 chain has a working load of approximately 100–140 lbf (445–623 N) depending on chain grade. The 9-tooth count means fewer teeth in contact at any moment, so keep operating loads within the chain's rated working load and avoid shock loading.
Carbon steel sprockets are susceptible to surface oxidation in humid or wet environments. For outdoor or washdown applications, apply a light machine oil or chain lubricant regularly. If corrosion resistance is a primary requirement, consider a stainless steel sprocket variant instead.
Keyway availability depends on the specific variant. Check the variant options for hub style details. If a keyway is not listed, the bore is typically held by a setscrew. Contact us to confirm keyway dimensions if your application requires a specific key size.
Bulk packs offer a lower per-unit cost and ensure you have replacement sprockets on hand for maintenance cycles. For production builds, robotics teams, or repair shops running multiple #25 chain drive systems, stocking spare sprockets prevents costly downtime when a tooth wears or a bore becomes damaged.
04C is the ISO/metric designation for the same chain standard that ANSI calls #25. Both share a 6.35mm pitch and compatible roller dimensions. This sprocket (listed as 04C 9T) is fully interchangeable with ANSI #25 chain in standard drive configurations.
