How do I know if my bike bearings are bad, and what do I do if they are?

I've noticed an odd grinding noise from my bike especially when I make turns. I read that rough ball bearings in my bike could cause this? How do I know if this is actually the problem and that my bike bearing are bad? What should I do to fix it if they are?...

How did Graeme Obree design and fabricate his homemade bicycle, Old Faithful?

I've been biking for a while, but never competitively. I ran across an article that said Graeme Obree built his own bicycle. Do any biking experts have any idea what went into his design or building process because I would love to know?...