Bill, for a great ride on the south side of the lake, (from Marble Falls) head south on 281 just about a mile south of the MF city limit sign, take a left (head east) on 2147 and it will dead end at Burnet County Rd. 404. Take 404 thru Spicewood. Be sure and cruise thru the LCRA parks. Lot's of great dirt roads in this area. 404 eventually turns into Paleface Ranch Road at the Haynie Flat Road intersection. Paleface RR will eventually hit Hwy 71. Take 71 east and cross over the river. Take a left on RR 2322 with dead ends into Pace Bend Park. You can ask the guy at the gate to let you just take a "check out" tour of the park, usually without paying if you promise them you are not going to spend the day. Bring your swimsuit! Once you leave the park you can head back towards 71. Just past the entrance of Briar Cliff, make a left on Bee Creek Road. This road is tight and twisty and a helluva lot of fun on a motorcycle. Be careful at the end of the road where it spits you back onto 71. If this sounds good, let me know as I am just now learning about a "secret" nearby county dirt road that crosses several big ranches and low water crossings. I have not been on this one yet but will let you know as soon as I do. From what I hear, it's excellent offroading for dual sport bikes.
We used to have a great Hill Country backroads map that shows all of the minor roads, dirt roads and old forgotten routes thru our area. We used to spend weekends exploring the roads in this area and we still have not been down all of them. Drop me a line sometimes when you are gonna do this ride and you can stop by my place for a splash of fuel and a swim in the river.