WASHINGTON — Under blue skies on a blazing hot day this summer, John Kerry hopped onto his bike, clipped into his pedals, and spent three hours on a grueling ride up a mountain in the Alps. This was a year after he fell off his bike and broke his femur. This was after days in the hospital and months of physical therapy. This was after he became the butt of jokes from Donald Trump. Now he was back on the bike, trying to ride the same Alpine pass, featured in the Tour de France, that he’d failed to complete a...