So how can somebody with little or no experience (me!) in frame materials identify whether an old frame (found at a garage sale, swap meet, etc) is steel or aluminum? Can you tell just by looking at the welds, or tapping on a tube? Yeah I know sometimes there are decals that tell the whole story, but what if there aren't any decals? What if the frame was repainted or something? I wouldn't know what a lug was if it jumped up and bit my a$$. Thanks. I hope some noob-tolerant guru can enlighten me.