Maybe I'll do the m&m's test. One of my childhood friends once rode four hours in a car with a handful of m&m's to see if they would really not melt in his hand. (They did.)
I should clip a piece of this fabric and tuck it into my bike glove when I go for a ride. Or put it between my foot and a white sport sock and walk around all day. If it comes out without having leaked dye all over me, I'll then say it's safe to make gloves and belts out of without a risk of colour transfer.