Different types of velomobiles and HPV's. These enclosed bicycles or tricycles are fully-faired to protect against rain and snow. Their aerodynamic fairings also make them faster than other trikes.

The PPV was a 1970's era human-powered vehicle in side-by-side tandem format. With plenty of space for groceries or a small passenger, it would have been a great fuel-saver, but it was doomed by its overly-complex 3-speed gearing, cheap components, and unwieldy width. With the end of the Arab Oil Embargo, hundreds of these ended up in storage, but they are now being restored and ridden by HPV enthusiasts.

"Delta" trikes can be chained together to build trains, the longest of which (so far) was ridden in the summer of 2007 at the Hase factory in Waltrop, Germany, with 93 trikes. This tandem option, besides being fun for the able-bodied, is great for disabled riders. One sighted leader can take a half-dozen blind cyclists on a safe outing, without worrying about balance. Physically-disabled riders can pedal at their own pace with the completely-separate drivetrains.