Converting a mini bike’s rear suspension hinges on the right swing arm and related parts. A proper fit improves handling, ground clearance, and chain alignment for 12-inch wheels and engines from 70cc to 125cc. The picks below focus on a compatible 12-inch rear swing arm and tensioners for dirt pit bikes. Use this guide to compare options and support a reliable upgrade for your build.
Summary of selected products:
| Product | Brand | Fit | Notes |
|---|---|---|---|
| CWTD Swing Arm | CWTD | 12" rear, 70–125cc | New |
| Keenso Red Chain Roller | Keenso | 10mm | Swing-arm ready |
| Keenso Green 8mm Roll | Keenso | 8mm | Durable |
| Keenso Green 10mm Roller | Keenso | 10mm | High quality |
| Senyar Yellow 10mm | Senyar | 10mm | ATV/mini bike |
CWTD Swing Arm For 70–125cc Dirt Bikes
The CWTD swing arm replacement is designed for dirt pit bikes with 12-inch rear wheels and engines ranging from 70cc to 125cc. This 450mm rear arm offers a robust upgrade for improving suspension geometry and chain alignment on compatible models. It aims to restore stability and handling when upgrading or repairing worn swing arms.
- Condition: Brand new
- Package contents: 1x swing arm
- Compatibility: Fits 12″ rear wheels with 70–125cc engines
Keenso Red 10mm Chain Tensioner Wheel
This pulley tensioner wheel is designed for swing-arm setups on mini bikes, dirt bikes, and ATVs. The red 10mm wheel includes heavy-duty bearings for smooth operation and helps keep the drive chain aligned as it passes over the tensioner. Inner diameter is 10mm, making it compatible with common 10mm axles and conversion kits.
- Heavy-duty bearings for smooth operation
- Keeps the chain aligned over the swing arm
- Inner diameter: 10mm; compatible with 10mm axles
Keenso Green 8mm Chain Roller
The 8mm green chain roller is built for compact mini-bike builds and swing-arm conversions that use smaller axles. It features sturdy construction for long service life, with an 8mm inner diameter suitable for 8mm axles and compatible with motorized conversion kits.
- Sturdy construction for long service life
- Inner diameter: 8mm; suitable for 8mm axles
- Designed with the swing arm to keep the chain aligned
Keenso 10mm Pulley Tensioner Wheel
The 10mm green pulley tensioner is designed for swing-arm setups on pit bikes and mini bikes. It uses heavy-duty bearings for durable performance and keeps the chain aligned as it passes over the tensioner. The inner diameter is 10mm, making it compatible with 10mm axles and common conversion kits.
- Good quality with sturdy materials
- Swing-arm oriented design for chain alignment
- Inner diameter: 10mm; compatible with 10mm axles
Senyar Yellow 10mm Chain Tensioner
The Senyar yellow 10mm tensioner is designed for ATV and X18 mini bike wheels, with a 10mm inner diameter. It can also be used on gas-powered motorized conversion kits for chain tensioners on tornado-style four-wheelers. This makes it a flexible option for various small-bike builds.
- Inner diameter: 10mm for ATV/X18 mini bikes
- Also usable on gas-powered conversion kits
- Suitable for a range of mini-bike applications
Buying Guide
Key considerations when choosing a mini bike swing arm conversion and related tensioners include fitment, compatibility, and installation ease. The most important factors are wheel size, engine displacement, and the swing arm’s length and mounting points. For 12-inch rear wheels and 70cc–125cc engines, ensure the arm length and mounting pattern align with your frame. Material quality and bearing life affect long-term performance, so prioritize robust constructions and sealed bearings.
Cargo and maintenance play a role too. A factory-new swing arm reduces installation headaches and offers reliable alignment out of the box. When selecting chain tensioners, consider inner diameter compatibility (8mm vs 10mm) and whether the parts are designed to work with swing-arm geometries. Easy-to-service bearings, corrosion resistance, and smooth operation minimize downtime and extend the life of your upgrade.
Practical installation tips consider your bike’s frame style, potential clearance issues, and chain tension needs. If you plan future upgrades, choose components that support common conversion kits and aftermarket hubs. Budget-conscious buyers may prefer a bundled set that includes a swing arm and compatible tensioners, reducing compatibility guesswork. Finally, safety matters: confirm all fasteners are torqued to manufacturer specs and inspect for wear after the first few rides.
Comparative notes for quick reference:
- Fitment variety: A 12″ rear wheel is common, but confirm axle diameter and mounting points match your bike.
- Arm length and geometry: Longer arms can change suspension behavior; verify linkage and chain tension paths.
- Materials and bearings: Steel arms with sealed bearings resist corrosion and deliver smoother operation.
- Ease of installation: Some arms and tensioners come with hardware; others require additional brackets or spacers.
- Maintenance needs: Periodic lubrication and inspection of swing-arm pivots and tensioner bearings extend life.