By GEOFF COWLES Bike Midwest Staff Writer DUCKTOWN, TENNESSEE — “It’s okay to stumble, but don’t fall. You can rest, but you can’t quit.” That’s sage advice for an extreme mountain biker. For Kevin Scoggins, they are words to live by. In 2005, Scoggins heard the words, “stage four non-Hodgkins lymphoma.” At one time,...