I'm coming from Wingsuit BASE jumping and whilst the risk of injury is higher in riding bikes, the risk of death is far lower so no hassles for me - not that I've given up the BASE...

Maybe a quick fabrication of an argument by comparison scenario would work for you. Something like a brief dabbling in big wave surfing, Himalayan mountain climbing, or a bout or two in the backyard Merrylands MMA circuit for a couple of months and she'll be buying new leathers and pushing you toward your bike.