Bought a Lynskey single speed 26″ mtb frame on classifieds (now repaired with some agricultural welding!), now runs 700c wheels, drop bars, full carbon rigid fork and 1.9″ 29’r tyres. Its a hoot on nice undulating hills, but hard work on my old legs on anything steep.
But it wasn’t built for that, whether it’s a mtb with drop bars or monster cross, I still love it!