On our tandem, 56 mph, stupid fast and don't care to do it again. On this hill, we never spun the pedals, it was all donwhill coasting. Tandem was rock solid but shades and helmets were rattling like crazy. I just think of what could have happened to my wife if a dog had run out in front of us!

Single, 46 max. Over 40 is when I have to think about what I'm doing, otherwise feels pretty natural.