*Specifications subject to change without notification*
Slackening the head angle puts the wheel further out front, increasing wheelbase and making the wheel self correct back into a straight line more strongly. That makes a short stem crucial to lever it off line on split second reaction singletrack or micro manage front tyre traction. That demands an extended top tube to stop the bike feeling cramped, further extending the wheelbase and increasing stability. A low bottom bracket also puts weight as low as possible to form a further stabilising keel effect when you're flat out on terrain that's trying to fling you into the trees.
You can't ride a stubborn, sluggish DH barge with no pedal clearance up Yorkshire sheep tracks so the RC127 is a careful balance of future wildness and proven wisdom.