Crash bars: For the protection sliders can't provide - RevZilla
Impaktech Crash Cage - Yamaha - STREETBIKE SUPPLY
Motorcycle Engine Protection Cages
The Exodus, by Suprine: A recumbent motorcycle powered by BMW | Motorcycle, Motorbikes, Cycle car
Motorcycle Roll Cage – The Babe Cage
Why has no motorcycle manufacturer built a recumbent-style motorcycle, where the rider sits lower to the ground and has a roll cage over his head? - Quora