StephenH, I go to the bottoms on Mondays when I'm off. I park in Sylvan park which is close to that canoe rental place on Irving Blvd. I've been riding the North side of the levee from Sylvan and all the way Northwest up to I-35N. The trail ends at the southernmost edge of Bachman Lake. I havent found a way to get up on the lake as there was some construction. The surface is gravely and sandy at some spots and compact dirt. Not an easy trail IMO but I like the challange. The tops of the levee is best to ride and the climbs up the levee makes for a great workout. On weekends the park is quiet but dirty 'cause everybody and their dog drinks beer there at nights but Mondays it's clean and quiet. You could also park in the industrial district of Westmoreland/ Mockingbird between the bridge and Irving Blvd and ride up onto the levee as well.
Ernest