I bought a Nashbar Hounder single speed bicycle last summer, and I've been looking to do some upgrades....also debating if it's worth upgrading, might be smarter to buy a new bike? Anyways, I wanted to know if I bought bought a 3 speed crankset, a tension wire, and kept my single-speed freewheel, would it work? or would I need to invest in a rear derailleur as well as a 8-9 speed freewheel? Also, I've seen single-speed derailleurs that might work with the 3-front chainring....any Suggestions?