As one of the important parts of a chainsaw, the sprocket transfers the power created by the engine via the clutch drum to drive the chain around the guide bar. There are two common sprocket types on chainsaws: the spur sprocket, and the rim sprocket. What are the differences between the two sprockets, and what are the features of the two sprockets? Let’s find out the answers.

The spur sprocket

The spur sprocket is a star-shaped sprocket wheel (usually between 6 to 8 points) integrated with the chainsaw’s clutch drum. The spur sprocket consists of 3 parts: the rim, the clutch drum, and the drum skirt. So if the spur sprocket is worn, you have to replace the whole sprocket. Engine power is transferred directly from the clutch drum to the chain through this integral part.

3 benefits of using a spur sprocket

1. More durable: stable construction and fewer contact areas with the drive links.
2. Easier installation: fewer parts to install - just one intact part
3. Easier to gear with chains: do not require further tension adjustment as much to remove or install a chainsaw chain.

The rim sprocket

There are 5 parts to a rim sprocket:, the rim, the bore, the clutch drum, the splined hub, and the drum skirt. It is convenient to replace the sprocket if it wears: you just need to replace the rim.

6 benefits of using a rim sprocket

1.Easy to maintain and replace: the rim is the only replaceable part when it comes to sprocket maintenance and replacement.
2.Better chain alignment: thanks to the free-floating rim on the splined hub, the rim sprocket features better lateral alignment between the drive links and the bar groove to reduce wear and derailment.
3.Quicker customizing: whatever the teeth size of the sprocket is, its interior dimension is unchangeable. So you can replace the chain for different cutting demands easier and faster.
4.Low cost: the rim sprocket is more affordable than the spur sprocket.
5.Convenient: as most maintenance and replacement focus on the rim, it is more convenient to maintain and replace the small part rather than the whole sprocket.
6.Resilient: unlikely to be damaged when a chain derails. The chain on the rim sprocket will slip out rather than chew up the sprocket teeth.
7.Adaptable: the rim sprocket can fit with different guide bar thicknesses, while the spur sprocket only lines up one size guide bar.

Note

The number of teeth on your sprocket will directly affect the cutting speed and performance. You’d better stick with the teeth count that comes with your chainsaw from the factory.

Conclusion

The rim sprocket is nice-to-have and convenient. If your old spur sprocket has worn out, the rim sprocket is the best choice.

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