Mix together a crisp September morn, fall foliage, a demanding course and a gratis cup of Surly afterward — if you’re of age — and you’ve got the makings of a dandy footrace. That’s the Surly Trail Loppet, now in its eighth year at Theodore Wirth Park. Sponsored by the same folks who put on the City of Lakes Loppet ski race, it offers half marathon, 13.1-kilometer and 5-kilometer distances. The longer races wind through the buckthorn and backwoods of Wirth in a course that’s always rising, dipping or twisting. A wave start has minimized the backups on narrow trails of former years. But be sure to bring your ID — one graybeard we know almost didn’t get his beer, despite looking several decades older than the legal drinking age. Sept. 21. loppet.org