On an idyllic summer night for Summit’s “Step Up Revolution” preem at the Chinese, helmer Scott Speer had an easy answer to the question of his biggest challenge.“It was the 110-degree heat in Miami every day last August,” he said poolside at the Hotel Roosevelt during the Tuesday night afterparty. “We were there for hurricane season so it stormed every day and the pavement was so hot that the dancers had to wear white gloves.” There was so much rain that a key sequence, with dancers dressed in suits and lugging briefcases, was moved indoors. “We only had four days and it never stopped storming,” he added. Speer, a San Diego native who had directed two dozen musicvids before landing his debut feature gig, said the dancers knocked him out every day of the 41-day shoot for doing what he couldn’t do. “I’m 6-foot-5 so I’m not much of a dancer,” he added. Producer Adam Shankman said he was most pleased with finding a new setting to make a fourth “Step Up” film. “You want to tell a fresh story without the audience rolling their eyes, so what’s a little rain if you can do that?” he asked.