Nightmare picking the correct drive rim/sprocket for your chainsaw?? All is explained here..

Drive rims come in x2 internal sizes - SM and ST.
That would be easy right - but not quite - the ST are standard across the board, Stihl, Husky, Oregon, Obscure Chinese brand - it's easy.
SM are all the same EXCEPT Stihl whose internal small measurement means their small SM interal rims ONLY FIT Stihl sprocket drums.
Find a range of rims here www.chainsawbars.co.uk/produc...
For technical questions whatsapp [phone]
For order and enquiries whatsapp [phone]
And chat with a human!

[@JeffSmedbron]

Stihl's small spline rim is also called mini spline. Ebay and Web sellers need to give inner circle dimension specs on their products . The sprockets they call small spline, most of the time are not the Stihl mini spline size.

[@chainsawbars]

I'm not sure they do call the Stihl internal size as mini - or I've not heard of it - but yes it would be good if the dimensions on shops were shown, That said as long as you know that the Stihl internal is different you should be ok.

[@dibiase9502]

Is there a limit to the pitch or size chains that a spline can handle or is commonly offered in? Not counting Stihl, why would you choose small spline or standard spline? Is one just for bigger saws? Or bigger chains. Thanks

[@catqueen1135]

Is there truly a difference between the different manufacturers as far as small spline rim sprockets or is it miscommunication of what people are calling the different types(sizes) of rim sprockets?

[@chainsawbars]

The Stihl SM internal measurement is different to the Oregon and Husky internal measurement.

[@brianmitchell535]

Thanks for the info. So, if I was going to replace my very worn sprocket on my Poulan 2750 farmhand chainsaw that is .325 pitch .050 bar width and 78 teeth (using an Oregon H78 chain) what would be the BEST one to use. Any help or advise would be awesome. Factory uses a spur sprocket but would like to transition to Oregon if I can. Thanks in advance.

[@chainsawbars]

You'd need to find a rim sprocket set up that fits your Poulan and you can only do that by scouring the internet looking for exploded parts diagrams and similar such info.

[@catqueen1135]

What are the inside measurements of the different sizes of rim sprockets? (mini 17mm, small 19mm, standard 22mm) is that correct? Why is there so much confusion, someone please clarify this.

[@chainsawbars]

You pretty much have it right - in many ways best to think of them as SM or ST internal - with the Stihl SM internal being the odd man out.

[@briankinzer4175]

So my chainsaw has a .058-.063 rim drive if I swapped a .050 bar and chain over to the saw would that rim drive still work as long as the pitch was the same on the .050 chain and bar? It’s 3/8 in case your wondering but I was just asking in terms of still using the 3/8 pitch .050 size chain instead beings there is more offerings for it out there than .058 gauge

[@chainsawbars]

The 3/8 drive rim will run all sizes of 3/8 chain ie. .063[1.6mm], .058[1.5mm], .050[1.3mm]