The head tube of KM-600 designed similar to taper head tube style.This way you can have tapered head tube style but use normal 1.125" steer tube for suspension fork.
The top tube and down tube having a "crease" that lines up with the head tube makes this frame more designed.
The down also has the “crease” shape from B.B. seat up to head tube.
These tubes are using SPF technology to diminish the weight.