Thanks for that link its really helpful. I guess your right its pretty pointless being that 3 x 7 is almost dead. Really my reasoning for wanting to build is because my local bike shop told me that the system on my bike is old and with mixed parts which is why Im not getting good shifting. That and my chainrings are worn and I been having a hard time trying to find a riveted crankset that would fit my aged loose ball bearing bottom bracket. If I can just get new chainrings that would be my final investment in this bike. Im starting to accept that I just need a better bike.

Any idea where I might be able to find a crankset for my bike? teeth count is 48-38-28 and it has a square tapered iso interface.