More than 10 million bicycles are sold in the United States each year, and Sram Corp. is convinced they could all use new gear shifters. The Chicago firm has designed one that fits onto the handlebar grip, so riders can change gears without moving their hands. The company's target market: racers and recreational bicyclists who are serious enough about riding to part with $120 for the accessory. Meanwhile, a major bicycle manufacturer is planning to market new bikes utilizing Grip Shift later this year. -- Leslie Brokaw