New Rear Wheel

[MahatmaAndhi]

Good morning,

I bought a bike, second hand, from a person on Gumtree. It's just called a "City Bike" and other than that, I can't find much information about it.
It looks like the same frame as the Carrera Intercity. The person I bought it from was eastern European, so maybe it was bought in another country and came over with them? No idea. I'm guessing.
What drew me to this particular one though is that it has disc brakes and that's pretty unusual on a folder. However, now I have a bit of a situation where I am unable to upgrade it past 8 gears (that's the biggest freewheel that I can find).
So my question is: Does anyone know of where I can get a 20" wheel with cassette-hub and is disc brake compatible?
I have a feeling that if I do go down this route, I may need to get the wheel built for me, but if there's an off-the-shelf option that doesn't cripple my wallet then I would consider going down that route.

Here's a picture of the bike with link to much bigger picture beneath.

Thanks.

View: https://i.imgur.com/vLXwTDU.jpg

 

[Cycleops]

Why do you want to change the entire wheel?
What do mean by upgrading it ' past 8 gears'? Do you want more gears or a lower bottom gear? If you want a lower gear why don't just get a another cassette?

 

[MahatmaAndhi]

Why do you want to change the entire wheel?
What do mean by upgrading it ' past 8 gears'? Do you want more gears or a lower bottom gear? If you want a lower gear why don't just get a another cassette?

At this point, I'm just putting the feelers out. But I am considering the Advent Microshift groupset which is a 1x9 and had a big range on the rear and solid favourable reviews.