This photo shows that yes, I can put the cables underneath the top tube ! I have this routing on my own bike and like how the cables are out of the way. I don't hear as much rattling on bumpy trails, either.
The classic wishbone of the tig. s.l. mountain bike frame , one of my staples for at least 18 years.
This smaller frame gets a downtube gussett and will be fitted with a 120 mm travel shock fork.
The bike will hold 2.3 tires and should be good on just about any type if dirt.