I've got a Cannondale tandem for sale, size is 25" front, 23" rear. it's the biggest frame size they made and the biggest non-custom available at the time, maybe still is. The front measures more like 24" front C-T, typical for C-dales. I believe it's a 1993. It's spent most of it's life hanging in the garage, so it looks like new. I may have spent more time upgrading and cleaning it than riding since I bought it to ride with my wife and she didn't want to ride. I'm selling it because my new wife is only 5'6" and can't fit. It's been upgrade to Shimano 8sp cassette hub with 48hole wheels and Deore XT rear Der. with flat bar shifters. If you're interest, you can let me know and I'll get you the details. If you're in or near central Iowa, you can come see it and take it for a ride.