Choosing the right rear sprocket can improve gearing, acceleration, and chain life on mountain bikes and comparable off-road machines. This guide highlights five Amazon options that fit common 420 chain systems and offer durable construction, easy installation, and broad compatibility. Each product emphasizes a 40-tooth or near-size option to balance torque with top-end speed, plus mounting patterns that support secure, tool-free installation. Use the buying guide below to compare bore sizes, mounting hole patterns, and installation requirements before upgrading your drivetrain.
| Product | Brand | Teeth | Compatibility Notes |
|---|---|---|---|
| CILOYU Mini Bike Rear 40T Sprocket | CILOYU | 40 | Compatible with Baja Doodlebu DB30, Motovox MBX10/MBX11, Monster Moto MM-B80/MM-B105, Coleman CT100U/CC100X, and more |
| CILOYU High Speed 420 Rear Sprocket 40T | CILOYU | 40 | Designed for Coleman CT100U, CC100X, RB100, MBX10/MBX11, Monster Moto, and other 212cc+ engines |
| 40T Rear Sprocket 6 Hole Replacement | Beienz | 40 | Fits Coleman CT100U, Mega Moto MMB80, Motovox MBX10; 6-bolt pattern for easy replacement |
| CILOYU 35 Chain Mini Bike Rear Sprocket 40T | CILOYU | 40 | Compatible with Predator 97cc/98cc/100cc, Coleman CT100U/CC100X, MBX10/MBX11, MM-B80/ MM-B105 |
| 41 Teeth 420 Rear Back Sprocket Cog | YD-PS001 | 41 | For Chinese 50cc–150cc pit/prod bikes, 170mm outer diameter, 76mm center hole |
CILOYU Mini Bike Rear 40T Sprocket
This CILOYU rear sprocket is built for compatibility with a range of common mini bike models and 40-tooth gearing. The design includes improved mounting hole spacing and six mounting holes, which helps ensure a secure, wobble-free fit on compatible hubs. The 40-tooth configuration favors smoother power transfer, aiding both acceleration and stable cruising on varied terrain. It is advertised as tool-free installation, with a straightforward replacement process that can be completed in minutes for many popular mini bikes.
- 100% fitment with Baja Doodlebu DB30, Hensim DB30, Motovox MBX10/MBX11, Monster Moto MM‑B80/MM‑B105, Coleman CT100U/CC100X
- Six mounting holes and updated spacing for broad compatibility
- 40-tooth design optimizes power transfer and chain operation
- Simple installation, includes hardware: screws, nuts, spanner, and master links
CILOYU High Speed 420 Rear Sprocket 40T
Designed for higher speed applications on larger engines, this CILOYU 420 rear sprocket offers a 40-tooth configuration with six mounting holes and a 49 mm center-to-center mounting footprint. The product targets minibike setups that use 212cc engines and larger, providing improved acceleration and sustained power delivery without sacrificing control. Its robust steel construction supports frequent riding and off-road use, while the six-hole pattern enhances stability and alignment during operation.
- 40 teeth with six mounting holes for broad fitment
- Specifically engineered for 212cc and larger minibikes
- Improved power transfer and stable chain alignment
- Durable construction suitable for off-road riding
40T Rear Sprocket 6 Hole Replacement
This Beienz 40T rear sprocket emphasizes broad mini bike compatibility with a 6-hole bolt pattern. It’s designed to fit the Coleman CT100U and Mega Moto MMB80, as well as Motovox MBX10 and similar models that use a 420 chain drive. The sprocket is manufactured from heavy-duty steel with protective plating to resist rust and endure high RPM performance. Its teeth are machined for smooth power transfer, reducing the risk of chain slip and prolonging drivetrain life. Installation is straightforward, making it a solid upgrade option for riders seeking reliable, everyday performance gains.
- Broad compatibility across popular mini bikes
- Heavy-duty steel with protective plating
- Machined teeth for consistent torque transfer
- 6-bolt pattern for easy replacement
41 Teeth 420 Rear Back Sprocket Cog
The 41-tooth rear sprocket cog from YD-PS001 is designed for a wide range of Chinese-made small bikes and ATVs operating with 420 chain systems. With a roughly 170 mm outer diameter and a center bore around 76 mm, this cog fits many pit/prod bikes and provides a slightly higher gearing option compared to 40T sprockets. The included 4 M8 bolts help simplify mounting, while the larger tooth count can aid top-end performance on flatter terrain or longer trail sections. This option suits riders seeking a modest gearing increase without major drivetrain alterations.
- 41T tooth count for modest gearing change
- 42- to 170 mm outer diameter range compatibility
- Includes mounting bolts for simple installation
- Suitable for a variety of 420 chain systems
Buying Guide
Choosing the right rear sprocket involves several considerations that affect performance, durability, and compatibility. First, confirm chain and drive compatibility. Many mini bikes use a 420 chain, but some models track different chain sizes or bore requirements. Match the sprocket teeth count to your riding goals: more teeth generally yield higher top speed but less low-end torque, while fewer teeth boost torque and acceleration at the expense of top speed. If you ride hilly terrain, a 40T or larger can be a good balance; for flatter, fast-paced trails, a 41T or similar may help.
Next, evaluate mounting and installation. Look at the bolt pattern: six-hole patterns are common and support robust alignment, but some models use four or five holes. Confirm bore diameter and the center hole size to ensure a clean fit on your hub. Material matters too; steel sprockets provide durability and corrosion resistance, while coatings can offer extra protection in wet climates.
Durability and maintenance are practical considerations. A well-machined tooth profile reduces chain slip and minimizes wear on both chain and sprocket. Consider how frequently you ride off-road and in dusty environments; a protective finish and rust resistance will extend life. Availability and compatibility with your bike’s model family also play a role, especially if you own multiple bikes or upgrade in stages.
Installation complexity varies by product and pattern. Tool-free options promise quick upgrades, but a mechanical inspection after installation is wise to confirm correct alignment. If you are unsure about fitment, consult the manufacturer’s compatibility notes and reviews. Finally, factor in cost and warranty when evaluating options, as higher-priced sprockets may offer longer service life and better resistance to wear in demanding conditions.