Tandem bicycles are great for allowing couples or friends to ride together, but they're not exactly conducive to riding by yourself. While you could just buy a tandem and a solo bike, one couple recently took a different approach – they got California-based Calfee Design to build them a tandem that can be converted into a single.

In fact, the clients actually got two of the bikes built. One was for themselves, and one was for a couple who are friends of theirs. We recently had a chance to see the bikes for ourselves in the city of Charlotte, North Carolina, where Calfee had them on display at the tenth annual North American Handmade Bicycle Show.

The other convertible tandem, in single mode

Company founder Craig Calfee had conceived of the design years ago, but shelved it away until the couple (who were previous customers) approached him last fall. It turned out that his concept met their needs.

"These guys travel a lot with their respective stokers [rear riders], six or seven times a year, overseas," sales manager Michael Moore explained to Gizmag. "They wanted to be able to ride as often as they wanted to, and not be beholden to their stoker. What they had to do in the past was simply ride their tandems as a single, so they were up front and there was nobody in the rear, and it's a very long bike, kind of clunky. So, this is an easy way for them to enjoy the best of both worlds – you ride it as a tandem one day, and the very next day you ride it as a solo cyclist."

The coupling point and the detachable seat stays

The frames of both bikes are made of carbon fiber.

In their single configuration, a bit of the top tube extends out behind the seat tube, ending in a circular coupling receptacle (it looks a little like the bike has a jet engine). When it's time to ride as a duo, the seat stays are detached below that device, and the whole back end of the bike is removed via two other coupling points – one towards the bottom of the seat tube, and one at the bottom of the down tube. The extended back end is then coupled on in its place, with the rear wheel swapped onto it.

It's all pretty clever, but not inexpensive – with their current high-end components packages, the two convertible tandems are each worth about US$25,000.

Company website: Calfee Design