When I'd decided I wanted a single speed, before I realised I'm fat, unfit and need gears, I bought a 2017 Kona Unit.
The 2018/9 ones have larger seat post tubes so you can run a dropper.
They're not boost spacing, they have replaceable sliding dropouts that are also tensioned in place by means of a bolt/nut arrangement, and because it's a Kona in unfashionable steel without gears or forks, they didn't sell them all, so there are loads floating around still, they'll take a taper fork with a different BB bottom cup.
Mines now geared, still rigid, running 27+ tyres again, but I go 29 sometimes with it too.
There's also the Big Unit if that normal one doesn't float your boat.
Cogwomble up there just mentioned something that's worth bearing in mind; last time I checked (which was two years ago) no-one was making Boost singlespeed-specific hubs. I've always happily taken the weight penalty of a steel freehub on my Hopes so I can run geared or single without worrying too much about either cheap steel cassettes or single cogs biting into the splines (and shouldered singlespeed cogs are peanuts these days anyway), but might be worth considering when looking around - if you're going for something with boost spacing, you'll probably have to use a 10/11/12sp hub of some sort.
I meant headset bottom cup, not BB, it's before I've had my daily caffeine dose..
PF30 frames - good idea, but hard to search by BB standard, any recommendations here? Some sort of spanky XC race thing might float my boat.
Boost etc - my preferred SS setup is normal free hub and spacers, I have some very nice wheels on american classics, normal spacing, so ideally I’ll keep using those. That said, if I need to go boost then just means new hub(s). Sadly you can’t get ACs any more, would probably go for some 240s or something.
Until very recently I only had singlespeed MTBs for well over 10 years.
For the last 4 or 5 years I've raced XC on exactly what you've described - a 'spanky fast' XC singlespeed. I went east for the frame and bought an unbranded Chinese import 29er carbon frame with a PF30 BB shell and regular vertical dropouts. Cost about 300 quid or so. Wheels Manufacturing EBB cups slot in and give a wide range of adjustment.
In a money-no-object world I'd have a Pivot Les, as they're lovely, but could neither find a used one in my size nor justify the cost of a new one and figured a Chinese import would be a low-risk way of seeing if this would work. Prior to that, I had a Gary Fisher Rig which had a Bushnell EBB, which was the first 29er I'd had. It instantly replaced all the 26ers - wow, a bike that fits properly! (I'm 6'1")
Aside from racing and training I probably spend most of my time on a MTB coaching and a light, fast SS has rarely been a barrier to any of that. 32:17 is my preferred ratio (I'm in Scotland, where there's hills).
My thoughts on the various chain tensioning options, having used pretty much all of them - tensioners may be effective but they're ugly (too ugly for me); slot dropouts (or track-ends, such as Inbreds have) are neater but you need at least a drive side chaintug and attending to rear punctures are a PITA; Bushnell-type EBBs are ace if you look after them but they weigh a ton and having to take a hammer to your bike to remove a component in a key area is unsettling, making small adjustments onerous; press-fit EBB cups (both PF30 and BB30 are available, I have both) are my clear favourite - they're light, you can fit decent bearings really easily, minor adjustment is easy without removing anything (you need a hex key and a track lockring remover) and they don't need much maintenance.
You can build a stupidly light bike this way for not a lot of money!
For wheels, I've a couple of sets of Stans Crest built on their 3.30 SS hub and another set built on a Hope trials hub. Both of these use a micro-cassette freehub body, onto which I use Gusset double-six sprockets and a couple of spacers to get the chainline spot on. Neater than a conventional freehub setup but 135QR.
The Hope hub feels (and sounds) amazing, as it has six pawls rather than three, but the Stans ones are WAY lighter and short of normal bearing replacement, need no special attention.
Hmm Chinese carbon is an interesting option - do you have a link to what you have, or where you got it?
I get the attraction of SS cassette hubs, if I need to go boost I’d try find one. If I can stay 135 I’ll keep with my american classics - nice and light and I find them very reliable. I think the big flanges build a nice stiff/strong wheel too, especially on a 29er.
I’ve had SS bikes about 16 years or so now, so I have tried most of the tensioning options (though admittedly not the EBB in a PF30 shell, so I’d consider it).
