Unless you were about to turn left, why didn't you just let him pass? I'm sure if I was the one driving and had to follow you in my car at 16mph for 10 miles I would have been pretty irritated too.
Just pull over for a single second... Would it REALLY have hurt you to stop your training routine for a single second? Thats really all it takes for a car to safely pass you. You can avoid confrontations by having some common sense in situations like these...