Do you think she could be convinced? If so I have a plan!
Wait 'til the biking season starts proper, and tell her you've heard about a pub that does really nice food by a canal, and bring her out on a Wednesday
https://www.facebook.com/group.php?gid=101268957247
When you arrive "Wow, where did all these bikes come from, can we have a look around?"
Be really interested in a yellow Gixxer we have for sale at a great price

, have the debate in the car park over whether you should buy it and we'll offer to buy you both a drink. We'll tell her how we are all experienced bikers, and it's not a dangerous as the general public would have you believe, in fact it's as safe as you want to make it. We'll even take her out on pillion for a nice smooth safe easy bimble, see if she enjoys it.
She thinks she was part of buying the bike, all sorted!