Hey all - a bit off topic, but I'll be in the Black Hills mid September and am looking for some advice on biking in the area. We will camp and climb in CSP and Black Elk wilderness, so we'll likely stay and bike in the southern hills, despite suggestions from a friend in Spearfish. I know there's bunch of resources and maps online but I figured I'd supplement those with your advice. I generally ride dh so gnarly is preferred, the steeper the better. PM me or chime in here if you want to talk about it.
Most of the best stuff is in the Northern Hills and Rapid City area also a lot of good single track in the Bear Lodge. You can access a lot of it from Nemo then ride North. Only 30-40 miles from the southern hills.