A quick look at our Drive Train:
http://flic.kr/p/9fHgBK
NOTE: the ground clearance you see is the actual ground clearance...after we put the wheels (mecanum) on the drive shafts, the bolts holding the robot up will be dremelled down as to not interfere with the field
perhaps the clearance will be a tiny tiny amount more but the wheel barely touches the ground with those bolts there
EDIT: sorry about the link, couldn't get the embedding to work