This is a little off topic, but from your apparent concern about having a flat, could we infer you're riding without patch kit, pump or spare tube? I know some people do, but at least here in the land of big thorns and broken beer bottles, flats are an expected part of every ride. One year back when I was obsessive about keeping records, I averaged a flat every 30 miles over a 1200-mile stretch in June and July (it's great practice, though--I can change a tube and inflate with a frame-fit pump in three minutes).
Good for you for sweeping off the path, but don't be one of those guys who isn't self-sufficient on the road. Carry what you need and know how to use it.