I love the design of these bicycle bookends, but I own more bicycle books that I can squeeze between them in the space between my shelves. Not that that's a design flaw, maybe I just have too many books on bicycling, I'm not sure. I have a copy of Forrester's "effective cycling" and a copy of Hurst's "the art of urban cycling," and that's about all the room I have on in between the uprights on my bookshelf.  They are big book ends, but they are pretty cool in design I think.