They are several contact points in cycling and your feet are the most important point because they are responsible for transferring power to the pedal. Over the years, as a professional bike fitter, I have noticed a reoccurring problem.Athletes are buying their cycling shoes way too big.  This causes unnecessary movement inside the shoe which consequently wastes power while cycling.  Other consequential issues of having cycling shoes too big are:  

• Hot Spots
• Numb feet
• Blisters

Your cycling shoes should feel snug without any lateral movements and shouldn’t experience any pressure between your toe and the front of the shoe. Don’t purchase the shoe if they feel tight and expect them to stretch. To obtain a perfect cycling shoe fit follow these steps: 

• The shoe must fit comfortably snug
• If you are able to move your foot back-and-forth then the shoe is too big
• Your toe should touch the front of the shoe but without any pressure
• You heel doesn’t slip up and down in the shoe
• Wear cycling socks for your fit test
• Try half sizes until you find the shoe that fits you perfect