RK Racing Chain GB420MXZ-112 Gold 112 Link Heavy Duty MX Chain

Our review of the GB420MXZ-112 finds it aimed squarely at serious motocross racers who need the lightest, strongest non O-ring chain for 50cc to 125cc open class racing. The single biggest reason to buy is the chain's combination of chrome-moly construction and RK's HIT heat treatment, which delivers an unusually high tensile strength for such a light unit; that strength is what will matter most on a race bike where durability and low weight directly affect lap times and maintenance intervals.

Key Features

• Chrome-moly construction: Provides a high strength-to-weight ratio so riders get a durable chain without excess mass.
• HIT heat treatment: All components are heat-treated with RK's HIT process to improve wear resistance and long-term durability.
• Oversized alloy pins: Special alloy pins increase shear strength, lowering the risk of pin failure under hard use.
• Seamless rollers and bushings: Smooth rolling parts reduce friction and help maintain chain life and consistent power delivery.
• High tensile rating: A maximum tensile strength of 5000 ft-lb ensures the chain can handle race-level loads encountered in aggressive MX/SX riding.

Who It's For

The GB420MXZ-112 is best for competitive motocross riders and privateers running 50cc to 125cc open class bikes who prioritize low weight and maximum tensile strength in a non O-ring package. It is particularly suitable for riders who perform regular maintenance and want a high-performance chain that is rated for professional-level stress.

Riders who want an O-ring sealed chain for longer, low-maintenance service intervals or those using larger displacement bikes outside the specified class should consider alternative sealed or heavier-duty chains made specifically for those applications.

Pros & Cons

Pros

• Exceptional strength for its weight thanks to chrome-moly parts and HIT heat treatment.
• Very light at about 1.76 lb, which helps rotational mass and handling on small-displacement race bikes.
• Solid construction with seamless rollers and oversized pins yields visible durability and good value for racing use.

Cons

• Non O-ring design means more frequent lubrication and maintenance compared with sealed chains.

Specifications

Our Verdict

The GB420MXZ-112 is a focused racing chain that pairs low weight with a very high tensile rating, making it an excellent value for competitors in the 50cc to 125cc open class. Riders who accept routine maintenance in exchange for reduced mass and superior strength will find it a reliable choice that holds up under hard use.

Frequently Asked Questions

Is this chain suitable for 50cc to 125cc race bikes?
Yes, the GB420MXZ is designed for professional-level 50cc to 125cc open class racing and carries a 5000 ft-lb tensile rating.

Does this chain use O-rings?
No, this is a non O-ring racing chain, so it requires more frequent lubrication than sealed chains.

What type of master link is supplied?
The chain uses a clip type master link for field-friendly installation and service.