My wife and I ride an Angletech Viewpoint tandem. You may view one at www.angletechcycles.com . It is great for us because I have a 33 inch inseam while her's is 25 inches. Our Viewpoint allows her to pick her own cadence or even coast while I am pedaling because she has her own shifter and gear cluster.

It's not for everyone, but we sure like it.

Michael