Originally Posted by
cycle_maven
Going to 7/8 speed cassette isn't a big deal- you can use your original crank, derailleurs, everything. There are some gotchas, though...).
If you want to go to 9 or 10 speed, then in addition you'll need a new crank, probably new rear der, likely new front der, new shifters and cables. At that point it's probably not worth it- you can get a new bike for nearly the same price as the upgrade components.
You won't need a new crank, but you'll need new chainrings. May be easier to just get a whole new crankset, but sugino rings are plentiful and cheap. You'll need a new chain, and obviously the new cassette and hub to accommodate it. You may or may not need new shifters and rear derailer, depending on how much "swing" is in the r.derailer, and how much cable the shifter pulls. The front derailer will not need to be swapped out, assuming you're using the same style crank.
Personally, i feel that this "upgrade" wouldn't be worth it, except insofar as going from the freewheel to the free hub. If, however, you're not bending rear hub axles, you probably won't benefit much. Of course, racers would disagree (for they desire smaller and more frequent steps, to maximize proper cadence), but i don't think anyone is racing miyata 710s, so no worries.
If you end up doing this upgrade anyway, pm me, as I'll possibly wanna buy most of the cast-off parts.
-rob