I am confused about which bike to buy. I am looking at two bikes. One is the K2 Shadow Nine 29 inch mountain bike, and the other is the Diamondback Response Adult XE Mountain Bike 2012. They are both around $400. I do not know too much about what are good parts or not. I will be riding mostly on paved roads. Which is better? Thanks

The Diamondback Response is better spec'ed and 24 speed but is 26" wheel bike......(looks like the 2013 is a 29'er) The K2 seems very low end on the spec's and is only a 21 speed with twist grip.. but is a 29" wheel bike, but at that price range I would think the wheels are not destined to stay true for long. I had a 2011 Diamondback Response.. it had great bang for the buck.. great shifting(trigger), strong wheels and decent fork.. Was a great ride and value.. Got it from Amazon.com and free shipping..

Oh. That's what I was thinking from what I learned online, but what is the true of a wheel?

+ 1 for the Diamondback, I'm a mechanic at a bike shop and they really are pretty good cycles for the money. On wheel true; go to youtube and check out bicycle wheel truing: https://www.youtube.com/watch?v=YiAEvXoBhM8
Cheers