The most crucial factor to search for in shimano cycling shoes - for normal road races or a triathlon shoe - is solid sole. This makes certain there is no 'cushion effect' which results in a a drop in power. Ideal is often a carbon-based sole even so this is really a an costly selection. If your budget doesn't permit a carbon shoe then normal plastic soled
triathlon shoes will do.
You also really should have a tight (but not too tight) at the heel and toes plus an universal snug feel around the whole foot. There should be no 'wiggle room' inside triathlon shoes as this will result in a loss of torque and inefficient foot movement, additionally to the chance of blisters.
You should be able to obtain your triathlon shoes on and off fast. You also have to do this at Transition 1 and Transition 2 throughout which time you'll be hot, exhausted and possibly still wet from the swim. An simple to use fastening system is key - the traditional 'three fastening' system seen in road shoes has been proven to be over complex. For that reason most triathlon shoes use a single, wide fastening Velcro strap. This is a great compromise, providing sufficient stability and protection while also uncomplicated and quick to make use of.
You might have likely spent a lot of funds on your bike, your helmet and your clothing. We appreciate if you want your shoes to look attractive as well. Thankfully manufacturers are aware that triathletes are stylish and have created some fantastic looking sidi cycling shoes.