When selecting a bike, it's important to consider the frame size and overall fit to ensure comfort and proper riding posture. For a person who is approximately 5.1 feet tall (or 155 cm), it's generally recommended to look for a bike with a smaller frame size and a lower standover height.
One option to consider is a road bike or a hybrid bike with a frame size ranging from 48cm to 52cm, depending on the specific brand and model. It's best to visit a local bike shop and get a professional fitting to determine the most suitable frame size for your body measurements. The shop staff can help you find a bike that accommodates your height and ensures a comfortable riding experience.
Remember that individual proportions, such as leg length and arm reach, can vary, so it's essential to test ride different bikes to find the one that feels most comfortable for you.