Before buying second hand bike you should check all features of bike is properly working or not.
When you go for a purchasing second hand bike you should go with a mechanic or knowledgable person in bikes.
Before purchasing second hand bike you should compare this bike with other because of in same rate much better than this bike are availables.
When your decision is final about buying second hand bike you should check all documents regarding to this bike and also cross-check this document.