Follows John Muir Blue loop a single-track mountain biking trail in the kettle moraine southern unit. I also went counterclockwise but start and finish near shelter 3. There are numerous potential shortcuts that could be taken from fire roads. My route was as conservative as possible, staying on the single-track trail. The trail is pretty well marked from either direction with the exception of MR8 which the signage misleads one onto the connector trails. If going counterclockwise take a hard left here.
Part of this route is a Strava segment (Squirrel loop) and it appears there are some extremely fast times and many too good to be true. However, there is plenty of room for improving this time.
https://dnr.wi.gov/topic/parks/name/kms/pdfs/kmsmuirtrmap.pdf
Admin Note: Jake did an earlier version of the Blue Loop which did not include the 1-2 mile Gnome Loop. The Gnome Loop seems to be part of the Blue Loop now, and should be included in the FKT.