Worn Motorcycle Sprocket

Checking for these three signs can help you determine if your motorcycle sprocket is worn:

First, see if there is a “shark fin” phenomenon in the tooth shape, that is, the tooth tip becomes bent to one side and is no longer a neat trapezoid.
Second, feel whether the tooth top is as sharp as a needle. Remember, the tooth top of the new tooth plate must be flat.
Finally, do a “zipper test” and pull the chain back at 3 o’clock on the rear tooth plate. If you can see a clear gap between the chain and the crankset (more than half of the teeth are exposed), then both the crankset and the chain are very worn out.
If any of these conditions exist, to prevent the chain from coming off or breaking, you must strictly replace the front and rear sprockets and the chain as a complete set immediately.

Observe whether the sprocket exhibits a “shark fin” pattern

This is the most intuitive way to judge the wear of the tooth disc. For a healthy new dental tray, its tooth profile should be a symmetrical trapezoid, which is designed to evenly bear the pressure of the chain roller. However, as the mileage increases, the huge torque of the engine will drag the chain to death on the driving surface of the tooth plate. Over time, this one-way force will wear away the metal a little bit.

When you check, you look closely at the profile of the tooth. If they look like rolled-up waves or shark dorsal fins-curved on one side, straight on the other, with a hook at the top-then the structure of the dental tray is broken. Don’t underestimate this “hook”, it will drag the chain rollers, cause the transmission system to vibrate, and most importantly, it will steal the power of your car.

Check the sharpness of the motorcycle sprocket

In the world of motorcycle transmission systems, sharpening teeth is the signal of obsolescence.

New dental discs: The top of each tooth has a flat surface. This plane can ensure that the chain can be inserted and removed smoothly.
Wear discs: As the tooth groove (the valley between the two teeth) is worn deeper and deeper, the material at the top will become thinner. Finally, the plane disappeared completely and became as sharp as a needle.
You can carefully scratch your fingers across the tooth tops (be careful not to scratch your hands). If it feels like a saw blade, or if it looks like a chain is going to be cut off, then the life of the tooth plate will be completely over.

Perform the “Chain Pull Test”

It is not enough to see with eyes alone. Only by checking the mechanical hand can the matching state of the chain and the tooth plate be confirmed. “Pull chain test” is our “gold standard” for diagnosing drive system wear in the industry “.

Operation steps:
Support the car ladder (or use the frame) to let the rear wheels hang in the air. Find the 3 o’clock position of the back tooth plate (that is, the most backward point). Hold the chain link there with your hand and pull it directly back, away from the tooth plate.

If it is a new transmission system, the chain should cling to the tooth plate and you can’t pull it at all. But if you can pull the chain apart and even see more than half of the teeth exposed in the gap, the system will wear out quite badly. This gap shows that the chain has been “elongated” (pitch extension), and the tooth groove of the tooth plate is also worn out, so the chain cannot be hung at all.

Replace the Complete motorcycle sprocket and chain Set

If you find shark fins, tines or pull chains that fail the test, the only solution is to replace them immediately. There is a death sentence here. It is crucial to follow the “Complete Set Rule”: Always replace the front sprocket, rear sprocket, and chain at the same time.

I can always meet some car friends who want to save money and feel that “the tooth plate is broken and only the tooth plate is changed” or “the chain is loose and only the chain is changed”. Believe me, the new chain with the old tooth plate (or vice versa) will only lead to devastating and rapid wear of the new pieces, because their pitch (the distance between the link and the tooth) simply does not match, and the bite is hard grinding.

Moreover, riding a bicycle with any of the above signs is not only a maintenance problem, but also a life-saving one. A worn drive system can cause tooth skipping, off-chain, and even direct collapse under high load. Once the chain is broken, the engine case is damaged or the rear wheel is instantly stuck, the consequences will be unimaginable.

Once you see the signs, immediately replace the full set, don’t hesitate.

Author ：Nick
As a dedicated rider and wrench, I treat drivetrain maintenance as a critical safety practice, not just a chore. I specialize in diagnosing mechanical wear—from identifying early “shark finning” to interpreting the chain pull test. I hope to help you catch these warning signs before they fail, ensuring you understand why replacing your chain and sprockets as a complete set is the only way to keep your ride smooth and safe.