I've gone through this kind of thing with my dh, too. I finally just had to realize for myself and then explain to him that since I get up and go to work every day, and I have a regular saving plan, and I'm not overextended financially, then if I want another bike I'll bloody well buy another bike.

Of course this works for us because we have always, in 25+ years of marriage, maintained separate financial accounts. Sure, we pay the mortgage and other household expenses together, but for all other money, to each his/her own. So if you have your own money and you're not deep in debt, what's the big deal?

And of course, he still razzes me for having too many bikes (3, and one's a cheap cruiser), but I can stand that.