Generic 40T High-Speed Rear Sprocket for Mini Bikes — 37mm Bore, 6-Hole, Hardened Steel

High-strength 40-tooth rear sprocket engineered to upgrade mini bike speed and durability while fitting 37mm bore, 6-hole mounting patterns for popular models.

This 40T high-speed rear sprocket is a precision-machined replacement part for a wide range of minibikes and small off-road machines. Built from hardened steel with heat-treated teeth, it accepts #40, #41 and 420 chain sizes and is designed to resist wear under repeated torque and chain friction. The 6-hole, 37mm-bore pattern matches OEM dimensions for direct installation on many Coleman, Mega Moto, Baja, Motovox and similar minibike models.

How will this 40-tooth sprocket affect my minibike's performance?

Switching to a 40T sprocket shifts the balance toward higher top speed with a slight trade-off in initial acceleration compared with smaller rear sprockets. The additional teeth reduce engine RPM at road speed, helping smooth out cruising and lowering chain stress at higher velocities. Heat-treated tooth profiles also keep chain engagement consistent for predictable throttle response.

• Raises top speed potential versus smaller rear gears
• Reduces RPMs at cruising speeds for less engine strain
• Heat-treated teeth resist premature wear from chain contact

Will this sprocket fit my minibike and how easy is installation?

The sprocket features a standard 37mm bore with a 6-hole mounting layout that matches OEM patterns on many popular minibike models, so it bolts directly into place without modification. Pre-drilled holes align with factory hardware, making the swap a straightforward mechanic or DIY job. Verify bolt circle and bore size against your wheel hub before purchasing.

• 37mm bore and 6-hole pattern for direct OEM fit
• Compatible with Coleman CT100U/CC100X, Mega Moto MMB80/105, Baja DB30, Motovox MBX10/MBX11
• No extra machining or adapter required when sizes match

What chains and loads is this sprocket compatible with?

This sprocket accepts #40, #41 and 420 roller chains commonly used on minibikes and small utility machines. It is precision-machined from hardened steel and heat-treated to handle typical riding loads, including recreational and heavier-duty conditions. Routine chain maintenance—lubrication and tension checks—will maximize longevity.

• Designed for #40, #41 and 420 chain sizes
• Hardened steel construction withstands normal torque loads
• Recommended regular lubrication and tension adjustments

How durable is this sprocket and what quality checks does it pass?

The sprocket undergoes load and wear testing to verify tooth integrity and bore alignment under operational stress. Heat treatment of the tooth surface reduces rapid wear, while precision machining ensures true concentricity for smoother chain tracking. These steps aim to reduce vibration and prolong both sprocket and chain service life.

• Heat-treated teeth to resist accelerated wear
• Load-tested to validate performance under riding conditions
• Precision-machined bore and hole pattern for accurate mounting

Who is this for: Riders and mechanics seeking a direct-fit, performance-oriented rear sprocket for minibikes and small off-road machines—especially owners of Coleman CT100U/CC100X, Mega Moto MMB80/105, Baja Doodle Bug DB30, Motovox MBX10/MBX11 and similar models. It suits DIY enthusiasts replacing worn drivetrain parts, shops upgrading gearing for higher top speeds, and anyone who wants a durable, OEM-pattern sprocket compatible with #40/#41/420 chains. Always confirm bore diameter and bolt pattern before installation.