Although people all over the world enjoy mountain biking, not everyone has year-round access to decent trails. That's why a group of British cyclists invented the Shoretrax modular track system. It ships flat-packed in the back of a truck, and can be assembled into different configurations on the spot.
The system was inspired by a network of roller-coaster-like elevated wooden mountain bike trails, for which the Canadian city of Vancouver's North Shore area is known. While those trails are fixed, however, Shoretrax can be packed up, moved, and reconfigured for variety or for different skill levels.
Buyers can choose from several packages, that range in length from 10 to 100 meters (33 to 328 ft) once assembled. Each kit contains a variety of trail module types, including ones that are straight, tapered, narrow, curved, or that serve as on/off ramps, drop-offs or rumble strips. Those modules can be put together to form either a point-to-point trail, or (in the case of the longer kits) a continuous loop.

Prices start at £2,450 (about US$4,000).
While it seems doubtful that anyone would use a Shoretrax setup as their one and only mountain biking venue, the system does look like it could certainly be useful for trade show demos and contests, instructional programs at schools, try-before-you-buy areas at bike stores, indoor mountain biking "parks," or simply for adding some interesting features to existing permanent dirt trails.
It would also be fun to put one in your back yard.