My friend Valeria Ottonelli at the University of Genoa (I'll be seeing her at a conference in November, when she will teach me how to pronounce my blog's name) has explained to me the Critical Mass bycicle event (see below).
It's a worldwide network of people who stage events at which they try to get enough cyclists together in one place (hence the critical mass theme) to call attention to cycling as an alternative means of transportation.
I happen to agree that it is a good idea to avoid burning dinosaur fossils whenever you can, so here is a tiny increment of free publicity for them.
(I actually don't even own a bycicle, but I am a big walker, both with and without a backpack, with and without trekking poles, both town and country, etc. I guess that makes me even more of a Luddite in a way than these cycling advocates.)