JMo - I am still checking around but you can find a good deal of info here: Skiatook Lake

Trihead - Not a whole lot of challenging trails at Devil's Den. Most are short, interpretive trails. There are a few 5-7 milers that you could run, but not sure about biking. The Butterfield trail is about 15 miles and will give you a workout. The wife and I were at Devil's Den a couple of weekends ago and had a great time. There are some great bike trails in the area, but I have never done them. Riding off curbs is about as extreme as I get on two wheels. Sorry.