Light(ish)weight Pompetamine

Out of interest, is there a common view on chain tensioners and vertical droputs? It seems a little clumsy and I'd prefer not to go that route, but if it gave access to lighter frames, I'm wondering how viable/practical it is? I see this as a last resort.

It's just a bit fugly and rules out riding fixed.

There are other options with vertical dropout frames; some kind of eccentric bottom bracket or chain half links / magic ratios etc.

If I were you I'd look out for the single speed specialized Tri-Cross in the second hand market - it's an ali frame with track ends. Frame and fork should be under 2kg. No disc bosses but discs and track ends aren't really best friends so no real loss there.