Okay first off I am riding a 2009 Giant Sedona Mountain Bike. If it matters I am about 360lbs or so. 36 years old.

I have been riding for a couple months now. Thanks to this forum I have bought all sorts of fun gear for my bike. Latest being a mirror and I just ordered my first pair of bike shorts.

I have worked up to doing 10 mile rides. I am trying to do about 3 or so of those a week with 2-3 smaller 6 mile rides. My butt right now is the fail point and I am hoping the shorts will help.

Anyways....

My question involves my speed. Generally I can hang in there about 9 mph - 11 mph for the whole ride. I usually am very consistent in that range. I will have dips as low as 7 if I am riding in 100+ degree temps.

Is this horrible? WAY to slow? I read all through here about you fellow Clydes bouncing down the road at 15 mph. Right now if I drop it all the way down and stand up giving it my all I can do 16 mph or so and nearly have a heart attack after a couple blocks.

Is it me? Do I need to work up to it? Or is it just being on a mountain bike with big fat knobby tires? All my riding is around the neighborhood on the street.

If it is the tires - do they make tires that can get me going faster?

Thanks all