Biker crashed into my back-thigh 48 hrs ago. Minimal pain so far. Does it mean bones are ok = I won't develop new pain days/weeks/months later?

That is what it mean. If there is only a minimal pain after 48 hours it means no bone is broken and you will be ok coming weeks and months.
Need a physical exam. Further evaluation with an exam and possible imaging (X-ray) to determine if complications may or may not arise from your unfortunate accident. Complications are possible if you leave this untreated and are having any discomfort. See your doctor or visit an urgent care center.