The only real critique I'll make is that in the first picture it looks like the right handlebar end might be bent vertical because it disappears out of the photo.

Light backgrounds work for many things, dark backgrounds also work as you have shown.

Somewhere on the web is a page showing one person's garage studio, roll up background cloth, portable lighting, tricks for getting a bike to stand upright without a kickstand and without the support showing in the pic.
Here is one I just Googled up: http://www.hetchins.org/503e.htm
Not the page I was thinking of, but nice just the same.
Enjoy.

edit: here is the page I was thinking of: http://www.raydobbins.com/photosetup.htm