Driving/riding fast is fine as long as it's not endangering others like what I encountered some time back.. I've had drivers that see me coming from the rear (that didn't sound right), and let me pass then tried to race me, sometimes I would entertain them, sometimes I would just either slingshot away or let them go ahead. We're really not racing, after the "duel" I would just raise my hand up and they would either smile/wave/thumbs up..
Just as long as the road is clear though.. Any zig-zagging through lanes stuff and I'm not game for that, not cause I'm chicken, I prefer not to get swiped by some racer in a car which I don't know at all.