About 5 years ago, my sil came for a graduation. She is fairly active (A level tennis player, some mtb), but had gained some weight. We put her on the Voodoo, with slicks and I went out with her for a 13 mile ride.
It was torture for me. I remember I was getting over bronchitis and I still had to stop and wait for her every 5 minutes. But, we did it.