Lot's of good MTB in Charlotte, and the surrounding areas. My favorite place is Sherman Branch - almost 11 miles of fast, flowing single-track with many technical options. It's on Rocky River Church Rd., just off of I-485 & Albemarle Rd.
You can also find out a TON of info at Tarheel TrailBlazers Charlotte's Premier Mountain Bike Club
- they're part of IMBA/SORBA as of Jan. 1, and their members build, maintain and advocate for MTBer's 'round here.