You can get pretty much the same performance with the Shimano Alfine 8 speed build into you rear wheel and your front chain wheel and no front derailleur or your front double chain wheel and the front derailleur (16 speeds). I've done the 8 speed version and it works well. If you do not want to do the modification mentioned, then your bike shop can do it for you. I seem to remember that my shop charged $350. two years ago.