Read the excerpt from Chapter 4 of Wheels of Change . Bicycle racing on an indoor track could be a thrilling sport for spectators, who sat outside the oval, so close to the cyclists that they could see their sweat. More than 7,000 people watched the night Frankie Nelson set her 18-hour record in Minneapolis, and a good number of those in the stands were female. "Men go to see what their brothers can do in the way of athletics," the St. Paul Daily Globe pointed out during that race. "Why shouldn't women be interested in their sisters?" Which central idea is developed by the quotation in the last sentence?