Going to purchase a mountain bike any suggestions.

[Spikesoftail]

Dept. store brands only come in a few sizes, and I've never found one that will fit anyone older than 10. They are also lower quality and put together by a Walmart/Target employees, nuff said. Hit up your local bike store. They have much better quality, the knowledge to get you onto the right size bike and will help you pick the right kind of bike for what kind of riding you'll be doing.