Ahh yes, I've had the same comment delivered to me. My reply? No different than previous replies, but a good opportunity for me to vent.
1. That speed limit sign is the maximum legal speed limit. There is no minimum speed limit on most public roads.
2. The next time you (the antagonistic cager) pull up to a stop sign or stop light, look at where you stopped in relation to the sidewalk.....that's why it's not safe to bike on sidewalks.
3. Almost all public roadways are legal for most any mode of transport...pedestrians, bikes, horses, cars, trucks, tractors....etc...
4. How would you pass a bike being ridden by your mother, sister, neice, etc???? That's how you should treat all cyclists on the road