In urban traffic, riding 9 miles (I don't do those foreign km things) on a rigid MTB on semi knobbly tyres, will usually take me 55 minutes, and never less than 50 minutes even with a tailwind. But then I'm not bothered about average speed, and I'm not trying to be fast.
I just ride at a nice steady pace which I could keep up all day if I wished.
Setting an unrealistic mileage target in a timescale is asking for failure or injury, IMHO. My weekly or monthly riding miles varies wildly according to the weather, how busy I am at work, and what other stuff I am doing. The riding has to fit in with everyhing else, and if I'm knackered after work or it's been pissing with rain every day for a week, the cycling gets put on the back burner until the time and inclination to go out for a ride increases.