I have a Giant MTB that I ride on either roads or fairly benign trails. Not jumping over boulders or pedaling straight up a mountain or anything. My bike has 3x8 gears, and I find myself not using the majority of them. Also, I think a lot of the time a shift of one gear is pretty useless, and I would rather just pedal a little harder or easier than shift through a few gears.
So, is it feasible to switch from this set up to something with 8-10 gears? I was looking at sites that sell derailleurs, but wasn't sure what I would need. Could I leave the front derailleur as is and just use the middle hub, then switch out the rear one, or will I need 2 new ones? What should I look for as far as number of gears, ratios, etc.? I'm don't know a whole lot about this stuff, but would like to get something that works for not too much $$ (don't need anything super fancy, lightweight, etc.).
Any help or ideas you can provide would be greatly appreciated! Thanks!