Hundreds of cities around the world now offer bike sharing systems, but if you're with a friend, why use two bikes when one could do the job?

That bike is the Duovelo, a conceptual sort of tandem, electric bicycle. The advantage of a second seat is obvious. It's one vehicle to transport multiple people, and hitching bikes together in a pedal-powered train could be a fun way to take a longer trip with family or friends.

Charles Bombardier About A mechanical engineer and a member of the family whose aerospace and transportation company builds trains, planes, and more, Bombardier's at his best when he ignores pesky things like budgets, timelines, and contemporary physics. Since 2013, he's run a blog cataloging more than 200 concepts, each a fantastic, farfetched new way for people to travel through land, air, water, and space. His ideas are out there, but it's Bombardier's sort of creative thinking that keeps us moving forward.

A cross between a BMX and a fat bike, the Duovelo uses a sliding mechanism to reveal a second seat for a passenger. The extra rider can hold onto a handlebar located between the seats, and rest his feet on lateral foot pegs.

This version of the concept doesn't include extra pedals, but it would be interesting to develop a folding pedaling system for the passenger.

An electric motor would assist the driver during his ride, with a charge indicator (visible even in daylight) on the crankset. You could ditch the e-power for a lighter ride, though it means more work for whoever's doing the pedaling.

The Duovelo itself holds two people (it's right there in the name) but could be connected with another of its kind to seat four, or even more. Imagine going on a bike ride with all your friends at the same time—on the same bike!

This original idea for this concept comes from Jimmy Bilodeau, who submitted it through my Imaginactive website. Adolfo Esquivel, a Montreal-based freelance designer, created the renderings for the Duovelo.