Hmmm. Here's an idea. It's not original either. O.p.'s wife has her TTR and likes it. Good. However, Specialized Roubaix and TTR probably cannot play nice together! If and when DH gets his trike will he also get a TTR or will he get something more ... spirited? Why not give the Mrs. an e-assist so the innate differences in horsepower (figurative) AND the differences in hardware, are equalized? Short of getting a tandem there really isn't a better way to allow people of different strengths or that have different vehicles to really ride together without the stronger rider loafing along well below an energy output that is satisfying.