If you simply want to move the shifters to a more accessible position, you could try bar end shifters. A quick look on ebay shows a couple sets of bar end shifters for Shimano 7-speed ( http://tinyurl.com/9qyjrcn ) - a few the original Shimano style, and one set is the Grip-Shift style. There might be gizmos available that allow you to position bar end shifters on the top of the bar, near the stem. If the bike has 6-speed shifting, you may be out of luck.
