Motorcycle Sprocket and Chain: When to Replace Them?

How to recognize the right moment to replace your motorcycle’s sprocket and chain.

The sprocket and chain are two essential components in a motorcycle’s transmission system because they are responsible for transferring the power generated by the engine to the rear wheel. Working in synergy with the chain, these elements allow the motorcycle to move and determine its ability to accelerate, maintain speed, and handle various riding conditions. They can directly affect the vehicle’s performance, engine efficiency, and, equally important, the rider’s safety. Worn sprockets or chains can compromise optimal power transfer, causing loss of traction, slipping, or abnormal vibrations, which can make riding difficult and dangerous.

Knowing when to change the sprocket and chain is therefore crucial not only to preserve the motorcycle’s performance but also to avoid damage to the transmission system and higher maintenance costs. A well-maintained transmission system ensures smooth operation, increased chain life, and a more fluid ride. However, since these components are subject to progressive wear due to friction, tension, and mechanical stress, it is essential to recognize the signs indicating the need for replacement, such as worn or deformed teeth, unusual noise, and difficulty shifting gears.

Knowing when to replace these two components is vital for any rider who wants to keep their motorcycle efficient, safe, and ready to deliver maximum performance.

Let’s take a closer look at the function of the sprocket and chain in motorcycles, when and how to change the transmission kit, and how to perform proper maintenance to extend its lifespan.

What are the Sprocket and Chain on a Motorcycle?
As we’ve seen, the sprocket and chain are key components of the motorcycle’s transmission system, and together with the chain, they form the “transmission kit.”
Specifically, the sprocket is a toothed wheel that transfers the movement to the motorcycle. It can have different configurations and is usually made of various steel or aluminum alloys. Gandini uses a special aluminum alloy, ERGAL 7075T6, for producing transmission components for track use. This material is lighter and more flexible, ideal for those aiming to reduce the overall weight.

The chain sprocket, on the other hand, is a small toothed wheel connected to the secondary shaft of the gearbox. Its rotation sets the chain in motion, which in turn drives the sprocket, allowing the motorcycle to move forward. Gandini manufactures sprockets from hardened and cemented 18NiCrMo5 steel, designed for durability and strength.

The chain connects the sprocket to the rear sprocket, transferring engine power to the rear wheel. This component is made up of a sequence of links connected by plates, and is typically made of hardened steel, ensuring resistance and flexibility, key properties for withstanding the stresses placed on it.

When Should You Change the Chain, Sprocket, and Gear?
Knowing when to replace the sprocket and chain is essential to avoid issues, ensure rider safety, and maintain high vehicle performance. Wear on these components is inevitable, but regular checks and good maintenance can help monitor their condition.
It is important to replace the entire transmission kit, including the chain, because replacing only one of the components may cause premature wear on the others. A complete replacement ensures optimal performance and long-term cost savings.

The lifespan of the transmission kit can vary depending on how the motorcycle is used and the maintenance performed. For example, if you frequently ride off-road or on city streets with constant stops and starts, the wear on the kit may be faster.

In addition to mileage, there are several signs that indicate the need to replace the three components of the kit, including:

• Visible wear on the sprocket and chain teeth: This happens when the teeth show signs of rounding or thinning. In some cases, the teeth may appear bent or chipped, indicating that the gears are no longer transferring power efficiently.
• Chain elongation: When the chain starts to elongate, it can become difficult to adjust properly. You can check elongation by pulling the chain away from the rear sprocket: if you can lift it significantly from the teeth, it’s likely worn.
• Unusual noises: Clicking, squeaking, or jerking noises while riding may be signs of an improperly aligned or excessively worn transmission kit.
• Reduced performance: A loss of power during acceleration or irregular response while riding could indicate issues in transferring power from the engine to the rear wheel.
• Abnormal vibrations: If you notice unusual vibrations coming from the transmission during riding, it’s advisable to perform a thorough inspection of the kit.

How to Replace the Chain, Sprocket, and Gear?
Replacing the chain, sprocket, and gear is an important operation that requires precision and the use of the right tools. Here’s a step-by-step guide for performing the replacement:

1. Remove the old chain: Remove the protective cover from the transmission, loosen and cut the worn chain using a chain extractor. If the chain has a joining link, remove it with the appropriate tool.
2. Remove the sprocket and gear: Unscrew the bolts fixing the sprocket to the rear wheel and remove it. Also, remove the gear, making sure to keep the fixing washers if present.
3. Install the new components: Attach the new gear to the engine shaft and tighten the bolts according to the manual’s specifications. Mount the new sprocket on the rear wheel, ensuring it’s perfectly centered. Place the new chain onto the sprocket and gear.
4. Secure the chain: Use a joining link to close the chain, ensuring it’s well secured.
5. Adjust the tension: Adjust the chain tension according to the motorcycle’s manual. Check the alignment of the chain with the sprocket and gear.
6. Final check: Ensure all bolts are properly tightened and perform a road test to make sure the system is running smoothly and without noise.

Gandini Race: The Perfect Partner for Quality Sprockets and Gears

Gandini Race is the division of Ingranaggi Gandini dedicated to the design and production of high-performance mechanical components, such as sprockets, gears, and motorcycle transmissions. The sprockets are made from extruded and forged solid aluminum bars, then subjected to finishing treatments. They are then hard anodized, deep black to 50 μ, and laser-engraved. This process ensures greater resistance to intense stress during competitions, offering up to five times the lifespan compared to the competition.

The sprockets are produced from solid 18NiCrMo5 steel bars. After finishing, carburizing, and hardening treatments, they are laser-engraved. The steel treatment, which includes surface carburizing followed by hardening and tempering, gives the material high hardness and excellent wear resistance.

All the transmission components made by Gandini Race are developed by an internal team of engineers and machined on state-of-the-art CNC machines. The finishing processes guarantee reduced friction losses, contact fatigue, and overall increased durability of all components. The company division is currently present in the world’s most important racing championships, including MotoGP, Moto3, WSBK, WSSP, BSB, and MotoAmerica.

Would you like more information about our products? Contact us.