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2012 UCI Track Cycling World Championships was held on April 4. 15 nations of 4 cyclists each participated in the contest. ️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️