Pillars are another great way of adding variety and challenge to your Bisikle tracks, and you can really use more than what you get in the base set. I find that you actually have to build overpasses a bith higher than shown in the base set, in order to really have enough room for the balls to go under - and here the extra pillars are a great help.
As I am always interested in unique games, Bisikle has filled a very different niche and has really been a ton of fun.
These parts allow for you to make inclines on the track. The original game comes with a fair amount of these, but I would highly recommend picking up one set of extras.