Sante Fe Road South??? Are you insane? You'd be better off heading South on I-25, which allows cyclists on the 20 foot median b/w Lincoln Ave and Castle Rock... if you can stomach hundreds of cars weaving around at the 75 mph speed limit b/w Lincoln and Castle Rock. Get off at the Meadows Parkway in Castle Rock heading West, turn South on Coachline Road, Turn West on Wolfensberger and then rejoin the mapped route at Highway 105. This route adds an awesome hill climb up the I-25 corridor with a wicked descent into Castle Rock, as well as a great descent off the backside of Wolfensberger Rd.
If you are going to attempt the no median, heavily trafficked, 60 mph, Santa Fe between 470 and Castle Rock with all of the SUV driving, cell phone talking, impatient drivers, then you had better leave very early and have balls of steel.
Note: As of 2006, they have resurfaced and widened Santa Fe for about 1/4 of the stretch b/w 470 and Castle Rock. I imagine they will eventually fix this cylcist death trap... but who knows when?