I have an older Schwinn hardtail and I am looking to do some upgrades. The bike has low-end shimano gears, a rock shox indy fork, some kind of V-brake(I don't know offhand), and Araya rims. I have upgraded the seat and the pedals to clipless, but I am having trouble prioritizing what to do next. What do you think the is the component that makes the most difference? Also, I was thinking about getting a new wheelset, but I have a 7spd, so I would have to get a new cassette and shifters to go 8 or 9, unless I use my old hub.