I'd address it with her: although the tone is overly harsh, she does have a point.

It's one of (many) hobbies that are not safe. It's also a pretty solitary and expensive hobby - the cost of a motorcycle would be put JUST to you as would all the time you would be spending driving it. That would take time and money away from the family. Which is ok if things are equal in your household - does your wife have any expensive hobbies that take her away from the family for a long time?

And like a lot of sports... it IS dangerous. There IS a large risk of injury with it. She's likely scared and worried for you, and scared and worried about how she would manage a household without you. Has it been a hobby you've talked about wanting to do for years, or have you only just recently sprung this on her? Does she think that you're going through a midlife crisis and trying to regain a bachelor-type status?

Not everyone is meant to be a caregiver - I'm certainly not. If I was married and my husband was so badly injured that he needed a full-time care-giver? I wouldn't be able to do it. Even trying my best, I would be terrible at it and the stress would slaughter me. I don't want to live my life like that. And if it happened because my potential husband chose to partake in a dangerous activity KNOWING that I was really against it? I'd resent him. If it happened because of some freak accident that had nothing out of the ordinary (so, like, a work accident or a regular car accident) that couldn't have been avoided? I'd likely have a lot more drive to keep trying my best to help them out.

It really depends a lot on the dynamics between you and your wife.

..... PS. I just saw that you have only recently told her of this desire - meaning that you've never really talked about it before. So it's not like she's always known that you were going to do this.. you've just sprung it on her. Even though it's a hobby for YOU, it's something that affects your WHOLE family and she does have a right to have her say. She just could have done it in a more caring manner.