Thinking about fitting one of these to a 1×10 slx setup.
Like the idea, what are they like to fit and use ?

They’re ok but you can end up with what feels like a yarning gap in the middle of your ratios. If my cassette was half way to the bin when thinking of doing this i’d go the whole hog and put a new cassette on with a wider gear range.

Given the cassettes that people off new and the price or expanders and cassettes, I think their time is limited. Sunrace cassettes work really well and seem to have as much range as a rear mech can cope with.

I just notice the gap with a 32T chainring but not a 30T.

Now that wide range cassettes are readily available I’d fit one of those. If you’ve a newish cassette that you can split then it’s worth getting one, just – since they cost almost as much as something like the Sunrace cassettes. I’ve found that I use that gear so little that the expander sprocket can last three cassettes. When my current cassette/extender wears out I’ll get a wide range cassette.

I thought the superstar 40t one worked excellent with an XT cassette.

I have an unused spare to sell if you want to save a few quid.

Can you split the SLX cassette though?

Yes but not as good as 11sp wide. Again you can’t split some of the cheaper cassettes so it’s never that cheap. I’d look at 11sp packages first

You can split the cheaper rivetted cassettes. Not too tricky. The availability of wide range cassettes has virtually rendered expander cogs obsolete but you can pick up 10 speed stuff pretty cheap now so it may still be worth it.

Thinking about fitting one of these to a 1×10 slx setup.

How big were you going to go? if 46 or less might be easier just to get a 10speed 11-4X cassette, can work only a little more expensive (or similar price to some expander set ups!) and no need for the bodgery.

Deore M6000 is available in 11-42 10 speed.
SunRace do 11-40, 11-42 and 11-46 options in 10 speed.

I was an early adopter of expansion rings. They filed a gap, but these days on my 1×10 I run the sunrace cassettes. I’ve not noticed any problems and it’s just less of a bodge.

When my 1×10 expires, I’ll be putting gx eagle on.