You earn the customer every time. They can always shop somewhere else. Any store or website can sell the same or similar product. Only service distinguishes you.
With each action you choose your customers.
You can have polite customers, or rude customers. You can have loyal customers, or cheap customers. Each choice you make selects your customers. What you do selects who returns. What you do determines who gets recommended to you. Mindfully choose your customers in each action.
Lately most bicycle retailers have emphasized selling high-dollar low-margin low-volume items: bicycles. Prices have gone up; quality has gone down; bikes sold has gone down; retailers in business has gone down.
Accessories and components have a good margin. An excellent opportunity for web retailers with lower overhead to lower prices.
If you sell more bikes than you service, you have failed to develop customers.