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JUST WONDERING WHY ??????????

whats the advantages etc as i,am a duffer/thick & unsure why is there a rim sprocket used anyway etc

Rim sprocket is much cheaper to replace and gives an easy option of using different configurations for different bar sizes etc.

Rim drives tend to be smoother and harder wearing than spur sprockets. Very generally, rims are mostly found on pro saws ......I KNOW THERE ARE EXCEPTIONS

I am told that rim sockets hold up better to stop/start cutting while spur sprockets hold up better to constant, heavy load, as found in milling. I've tried both for milling and this seems to be correct.

Alec

I fitted rim sprockets to all my saws (both of them - joking) The advantage is you can fit larger dia sprockets so I fitted an 8T .325 to my MS 280 to give it a bit more 'wiz' and fitted an 8T 3/8 to my MS 460 (twin port exh) when using a 16" bar - that really 'wizzing' through, makes my MS390's performance like a 'push and go toy'. Overall I found them running smother.

I would say rim sprockets last way, way, way longer than spur sprockets.

Spurs sprockets I find are very durable and hard wearing and as spud said generally are found on the domestic/semi pro and some pro saws.
Rims have the benefit of "floating" on the splines of the clutch drum and can move laterally allowing the chain to be kept in line with the sprocket even if pulled off line in the cut where spurs don't allow this so can cause wear to the chain.

I'd agree with that. I do find on big saws and long bars you're replacing the rim pretty regularly at least every x2 chains. A spur sprocket does seem to last longer when milling with a large saw.


But rims are cheaper, easier to change and as said very simple to swap a smaller one for a larger if you want to increase chain speed so if you have the choice I'd always go for a rim and sprocket set up. They offer more support to the chain drive links as well.