Here's a $5.-+ shipping cost solution.
http://www.cateye.com/cat/parts_list.php?products_id=64
Get a bracket(H-27), second from top, and spacer, bottom. It's as compact as it can be and quick release. Original screw that connect the spacer to the body is not standard tripod mount size which is 20x1/4, but you can easily drill a hole larger and the screw is readily available at local hardware store. You also need a piece of ruber sheet goes between the camera body and the spacer, so the camera won't sway side to side.
If you are planning to take shots while you are riding the bike, it's a very good idea to have vibration free camera. It's quite common in video camreas but you have to pay quite a bit for still photo cameras equipped with it.
Remote control will help you a good deal too, either wired or wireless. Keep in mind that some cheap remote controls have a few second delay and not instant triggering, which, I think, is pretty dumb.