Interesting option. I found another way by using the 404 error page to look at the bad url and then redirect to my domain.com/bikes (mojo existing) page if there was a match. Sorry, I should have posted my solution.
The 301 wouldn't work in this case and either would the file extension removal. Clients often want direct urls long after pages are created, or direct urls that we wouldn't really want to name (or change) a page to.
I like your option as well, I'll have to look at both and see what is best for the longer term.