You are not charged for traveling on Hwy16a. Just stay left and pass by the booth. You will now travel about 20 miles of more twisty and scenic road. Ride slowly in this boulder area. Continue down the road, past Sylvan Lake, to the junction of Hwy 385.
Hill City is similar to Keystone, shops, souvineers and liquid refreshments.
The next 17 miles is scenic and you move pretty well. At Rimrock junction, Hwy 44, turn right. It's now 18 more beautiful miles to Rapid City. On Hwy 44 you will pass Black Hills Caverns and Cleghorn Springs fish hatchery. If you don't want to return to Rapid City, stay on Hwy 385 for 28 miles and you will arrive in Deadwood.