You can't ride a mountain bike on the trail.  They don't even allow dogs on half of the trail.  If you go clock-wise around the loop the ascent is fairly mellow as it follows Cold Creek up the canyon.  If you start out counter clock-wise, you start off with some serious climbing.  According to the website above, you gain over 1000 feet of elevation in 0.5 mile.  I ran it, so my legs were burning like mad on the climb.  I thought my heart was going to jump out of my chest.  Once you reach the top it's fairly easy, though.