Monday, December 7, 2009

The Perfect Back to Back Tandem

With the onset of standard time, winter and the rainy season here in Houston, my thoughts turn to next year and a new, improved, back to back tandem. I asked myself what features I'd want if I could design a ground up back to back tandem. I'm not a builder or a technician, so this entry won't be about technical specs for a new bike. rather it's just a musing on what I like and don't like about the two back to back's I've owned so far and what I would keep or change in a new one.

My first back to back was the Flevo. It was fast and comfortable. It's speed probably derived from the recline angle of the seats. On the other hand, it was very long, very heavy and fairly unwieldy. It's 26" wheels made for a pretty high ride and this could be unsettling when riding backwards. It wasn't a technically advanced bike. The bar on which the bottom brackets travelled, for instance, was composed of solid metal stock. The bike came apart in the middle by backing out two large screws. I trailered the bike so disassembly wasn't necessary. The connection joint did allow for a bit of flex between the two halves. Even allowing for it's plywood frame covered with aluminum, the bike still tipped the scale at over 70 pounds. Still, the bike was an eye catching beast. I sold it this year after my stoker broke her hip and declared she just didn't want to be that high off the ground anymore and risk a fall.

Next came the Barcroft California. I'm still riding this bike, of course. It was and is a significant improvement over the Flevo in several respects. Being low to the ground it's easier to start and stop. It's almost as fast as the Flevo was. I suspect it would be even faster if we could recline the seats more, but they are so close together at the top now that more recline is impossible. Like the Flevo, the California comes apart at the middle. I've never disassembled the bike. The connecting joint is rock solid, however, so there is no possibility of Flevo flex there. The biggest drawback of this well designed innovative bike is it's weight. Like the Flevo, it tips the scale at around 70 pounds.
The obvious answer to the weight problem is a carbon fiber tandem, like the M5 Double D here. It's not for sale though, so I am left to imagine building a new CF bike of my own.
As I mentioned above, I like smaller wheels since they keep my stoker close to the ground and make the bike easier to start and stop. Independent front and back drive makes sense from a number of perspectives. It eliminates the need for a long chain to the back wheel and the power sucking idlers it requires. In addition, my stoker is completely sold on the independent cadence that we enjoy on the California. This is possible only with separate drives. A CF frame would result in a substantial weight savings. Lastly, to get the the additional speed we had on the Flevo, we need a seat recline of around 20-25 degrees.
With all of these thoughts floating vaguely around in the back of my mind, I came across this photo of John Morciglio's CF M2 mid racer. I realized that I could be looking at the front half of my dream back to back tandem. The size is about right. The seat recline is right. The CF frame is right. It only remains to contact a skilled craftsman and builder to explore the possibility of bringing this concept to life.
Stay tuned.