Bill-
Chimney Trail/Grading Camp has eroded out rather substantially the last couple years. Surface is composed of crumbly granite that characterizes the Pipestone area and weathers at a good rate. The NB descent has some sharp curves and sharp edges you'll want to keep an eye on, but the distance is short (~1 mi) and the grade isn't especially steep. You'll want to go slow especially through the boulder field where it comes out onto Milwaukee Road Tr.
The local Friends of Thompson Park group recently reached out to ACA and suggested Crook Camp Tr. as an alternative. This trail is twice as long and sports more climb (SB) than Chimney Trail, though they claim the surface is smoother and easier to negotiate fully loaded. This option may have appeal for you. You'll still miss the trestle bridge and two tunnels (the longer of the two tunnels can have ice even in summer so be cautious for anything resembling a watery surface). The bridge is a cool sight, but for now it will require an out-and-back. Getting down to Roosevelt Drive from the bridge is not something we can recommend since the terrain is so steep and rugged at that point.
Milwaukee Road Tr. is a fantastic riding experience and I wish more miles could be added to GDMBR. There's access issues on north end where the road leaves county maintenance and the landowner has gated and posted signs. And on the south end, from Pipestone Pass TH riders can either take to the highway or hop on the CDT. Maybe for future ACA can discuss linking Pipestone Pass TH with Highland Rd. via CDT and Lime Kiln Rd., but currently that equates to lots of singletrack, not necessarily the first choice for fully loaded GDMBR bikepackers.
Nathan
ACA
