Bergmonch Folding Backpack Bike
What a way to go: backpack up a mountain, then ride the bike you carried up hill back down! The website is in German, but it appears the bike is 9.5 kg, or 21 pounds. Which is only 5 pounds lighter than the rest of my backpack for a 3 day trip (including food and water!)
From: Backcountry.com: The Goat » Blog Archive » Bergmonch Folding Backpack Bike