Thanks guys for the responces. I am NOT an aggressive rider anymore, after my wife was hurt at Carter a few years ago it pretty much made me realize I needed to scale back cause our family can't afford another major injury. I mostly just ride for exercise now, mostly at carter and Alafia, and usually just the intermediate trails with an advanced trail mixed in here and there.
I don't know about 20" bikes on these trails, I have yet to see an adult ride one out there and can't imagine it would be much fun. I do see some kids riding everyonce in a while on 24", but I also saw kids on friday that look about 10-12 years old riding 29ers out there.
Let me ask some specific questions then.
-Would me being 6'3" and 230lbs would a 29er fit me better? I have always kind of felt a little large for my bike even though it's a 21.5" frame.
-I know they help smooth the bumps out and roll over things easier, but what about climbing? does the larger tire allow more surface contact area and increased grip?
-I've heard they are faster at speed and easier to maintain speeds, but are the gear ratios adjusted to make them equal to a 26er when climbing?