Just an FYI for those who hadn't heard yet. Apparently, a 10-12-mile Tough Mudder race (maybe the one held at Bear Creek last year?) is being planned on a 600-acre piece of land owned by the Jaindl family in Heidelberg/Lowhill townships just west of the intersection of Route 309 and Mill Creek roads on June 1-2, 2013. The organizers have been applying for a bunch of permits from the townships.
According to the Northwestern Press weekly newspaper and WFMZ-69 news, they're expecting 17,000 people to participate/spectate on June 1st with far fewer on the 2nd. You'll probably want to avoid riding at Trex on June 1 - the traffic on those back roads will probably be pretty bad unless they're shuttling from someplace like LCCC. Even then Rt. 309 would probably get pretty bad.