Zoobombing in Portland USA

isn't the thing that its kids bikes? but then they showed loads of people on regular bikes.
and surely its just that thing where you bomb hils on a low down bike to get the top speed forget the name,

still if i get sent to WHQ for work i'll do this.

You're thinking gravity bikes.. something else they do in the 'nongs..

http://www.gravitybike.com/Gbikes/What.html

http://www.gravitybike.com.au/news/life-in-the-fast-lane/