My wife blessed me this Christmas with a 17 Specialized Hardrock Sport 29 w/ disc. I raced a ton of bmx as a kid, but have never owned a mountain bike. This rig feels a bit short to me. As if I should have more space between my ass and the handle bar. LBS says its the correct size. I'm 5'10, 160lb. Again Im not sure how it should feel exactly as I am not familiar with mountain bikes per se. Does this sound about right?