We used a Tandem (defined as a whole bicycle) from a friend of ours (the one in the picture we eventually bought!!!!) to ensure we are "compatable". With Tandems you have one of two things..................you ride straight into a new honeymoon or you ride straight into the divorce court. A can be seen on the photos we are compatible, I only wish we discovered this twenty years ago. We would have been (more) competative.
We both started cycling a year and a half back. My wife stayed the "fun" cyclist with no inclination to compete or better her times. I kept on trying to become better. The problem arose when we pratised either I had to do it alone or ride at her slower pace. That was very frustating. What I did not know is that I unleashed a MONSTER!!!!. SHe is now the one who wants to go and ride a golden medal Jock!!!!! We are now running at about the same average speed (29km/h in the 94,2) I was racing at when I still raced with my half a bike.
One thing I can warn you though is that once the worm starts to turn, as it has with you, it is very dangerous. It WILL keep on turning till you have your own whole bike.
Keep those wheels spinning....see you soon with your spanking new tandem!!!!!!