I ran 30 tooth oval SS with a 15 or 16 depending on how the knees felt!!!. No problems at all.

You'll want a lower gear than 30x15 because the wheel size effects the gear inches...

so 32:16 with a 26" wheel is 52"
But 30:15 with a 29" wheel is 58"

I run 34:19 on my 29er. So you might want a 17 or 18 tooth cog with a 30t front.

To offset the change in wheels you'd probably want a lower gear anyway so 30t and 16t or 17t on the rear would be either side of a 32-16 anyway.

Downsides? Your drivechain is a few percent lighter and wears out roughly the same percentage quicker?

Thanks perfect advice. It’s a goer! What sprockets for a Hope Pro 2 hub? Presuming something wide at the fitting point so it won’t chew…

I’m running 30 x 17 on a 29+ singlespeed in the Peak District which is just about fine for the riding I do. Go for a Surly one as they’ve got a nice wide base and made of steel so last ages too.

On my 29er I started with 30*19, it was a bit spinny on the flat so now I'm in 30*18 (round ring).

I'm on the hilly South Downs and it's a good climbing gear.

BITD I used to run 32:19 when I single speeded my 29er, was just about perfect

Why not go bigger at the back rather than smaller at the front?
I used to have 34 oval / 19T on my 29er, moved to a hillier area and now happy on 21T rear.

More teeth = longer chain = slightly slower wear rates. Larger sprockets for the same ratio also reduce chain tension slightly and should run smoother as things wear or get dirty due to less chain wrap - I don't know the maths to say by how much but I'll take any small gain available to reduce wear and have a smoother running SS. I'd use a much larger ring on the front if it fitted, 38 or 40 maybe.

I’m running 30:18 on my 29er. I went with a 30t chainring to gain a little extra clearance at the BB for teetery log rolls - am also running a bash guard for the same reason. Feels a nice gear for playing in the woods for a few hours on the South Downs but have yet to take it further afield.

What sprockets for a Hope Pro 2 hub? Presuming something wide at the fitting point so it won’t chew…

On-One groove armada are the perennial cheap choice, if they're not available then surly (or i think arundell (SP?) sell the same ones without the logo. Anything wide will be much of a muchness as long as your chain fits.

I'd buy a few different sizes of sprocket as they're relatively cheap. This gives you chance to get used to riding singlespeed again in a slightly lower gear than what you were used to. You can then swap them out as you get stronger and are more used to riding singlespeed again.

One thing you'll notice riding a 29er singlespeed, is how it holds its speed better than a 26er. Seems more noticeable on a singlespeed than on a geared bike. I think you'll like it.

Charlie the bike monger is still good for singlespeed components (I know it's not actually Charlie anymore but the shop still is good)

https://www.bikemonger.co.uk/single-speed-cassette-cogs-227-c.asp

Why not go bigger at the back rather than smaller at the front?

OP states price is a factor. I did it as the bike came as a 1*11 and I didn't want to change the front ring for the sake of it.

Also to the OP, you don't really need to have a narrow-wide on a singlespeed, unless you are using a weak tensioner perhaps. Might open up your options a bit (and of course a narrow-wide won't work if you want to put a half link in the chain)

Track ends so no need for tensioner. Will use tugs for alignment. Yeah any 88 BCD ring for SS seems hard to source unless going Wolftooth at £80 a pop

I found a used 30T for £25 but not sure how much wear so looking at North Shore Billet options 50 quid.

I use an old narrow wide chain ring on my singlespeed with no issues.