35 Chain vs 420: Which Chain Size Is Right for Your Bike?

When upgrading or replacing the drivetrain on a mini bike, go-kart, or small motorcycle, one of the most critical decisions you will face is choosing the correct chain. Get this wrong, and you could face poor acceleration, premature wear, or a complete drivetrain failure. While both the #35 chain and the #420 chain look similar at a glance, they are designed for entirely different performance envelopes. If you are stuck in the dilemma of 35 chain vs 420, this guide will break down the key structural differences, speed capabilities, and torque handling to ensure you make the right call for your specific build.

Understanding Chain Dimensions and Physical Specifications

Before we dive into performance, it is essential to understand the anatomy of these two chain sizes. The numbers in chain naming refer to the pitch, which is the distance between the centers of the roller pins. Ignoring this crucial measurement is the easiest way to buy the wrong part.

• #35 Chain: This is a small pitch chain, measuring a 3/8-inch pitch*. Unlike the larger 40-series chains, the #35 features a narrow width. It is typically used on lightweight machines where weight reduction is a priority over brute strength. Because of its compact size, it rides on relatively small sprockets, which helps with quick throttle response.
• #420 Chain: This is a larger, heavier-duty chain. The pitch for a #420 is 1/2-inch. Crucially, a #420 chain is the same width as a #40 chain (yes, #420 is a lighter version of the #40 without the bushing), but it is significantly beefier than the #35. The larger rollers distribute load better across the sprocket teeth, which is vital for high-stress applications.

The simple rule of thumb is that the 35 chain saves weight and rotational mass, while the 420 chain saves your engine from wear in high-torque situations. But how does this translate to actual riding?

Weight, Rotational Mass, and Acceleration

In the world of small-displacement engines—think 50cc to 125cc pit bikes and mini choppers—every ounce of rotational mass matters. The #35 chain is significantly lighter. This reduction in mass means the engine doesn’t have to work as hard to spin the drivetrain. The result is a snappier, more responsive throttle that feels especially aggressive when launching from a stop. If you are racing on a flat track and acceleration is your primary goal, a lightweight #35 chain is often the preferred weapon of choice.

However, this lightweight comes at a cost. The thinner side plates and smaller pins in the #35 chain have a lower tensile strength rating. If you are running a modified engine with high compression or you carry a heavier rider, the #35 links can stretch, causing the chain to slap against the swingarm and eventually skip teeth on the sprocket.

Torque Handling and Durability: The Heavyweight Champion

When the terrain gets rough (mud, hill climbs) or the engine gets stroked out, you need a chain that can withstand sudden jolts. This is where the 420 chain steps into the spotlight. The increased pitch (1/2 inch) means each link