My LBS installed a new 7-speed cassette going from a 14-34 to an 11-34. I essentially lost my old 4th gear. I picked up almost 5 mph on level roads & trails to 20 mph and increased my average speed by 2 mph. This speeds up my commute and allows me to do greater distances during my bike-trail rides. When I get the funds I plan to install an SRam dual drive hub to give me evn greater flexibilty.