Sand!

We are considering the following aspects of bicycles in a sandy terrain like the Sahara desert:

Sand is often considered to be quite an unusual ground to ride on with a bicycle.
We are gonna change that.
We are gonna devise a bicycle which is able to ride on any kind of sand (desert, quicksand, moonsand) whereever you wanna ride, whenever you wanna ride.
Tornadoes, hurricanes, earthquakes, alien invasion: when we're done with our project, they will never be a threat to bicycling-humanity anymore.

On a more serious note:
When riding in a forest, some parts of the path can be sandy and slippery. Especially when there's much sand at a turn, bicyclists have an increased risk of falling. By exaggerating these kind of circumstances, we want to investigate this dangerous environment.

We intend to use Interactive Physics to simulate slipping in a rough terrain (any advice from D. Winch would be welcome). We probably don't have enough time to actually take field data on this subject, but we want to consider this a thought experiment.