For a long time, I went to school with a blind kid. In middle school, he'd go on the skiing field trips with a guide, and in high school he ran cross country (his dad would run with him in the races, we'd run with him in training). I think when you are blind you have to have a great deal of trust in your guides no matter what you are doing, so it's not a stretch to jump on the back of a tandem and do that.