Originally Posted by
Rambetter
I'm looking for a stoker stem, seat tube diameter 27.2mm and handlebar clamp diameter 26.0mm...
I think the adjustable stoker stem from our 1999 Cannondale RT1000 is what you are looking for. The handlebar clamp is 26.mm, but I'm not positive about the seat post clamp.
I'll measure it and post a picture tomorrow. It's actually such a nice polished aluminum piece that I enjoy just looking at it, but I'd rather see it doing what it was designed to do on someone's bike!