That's a pretty typical construction for a cradle tube frame. A Triumph Tiger 800 is not a high performance bike. Cradle frames are cheap, the bikes that have

That's a pretty typical construction for a cradle tube frame. A Triumph Tiger 800 is not a high performance bike. Cradle frames are cheap, the bikes that have bolted on subframes typically have backbone frames and use the engines as stressed members. Also that subframe attachment is an adjustment point for fine-tuning rider position.