Optimum hold and rigidity of the foot with the shoe means adequate energy transfer from your legs to the pedals, cranks, chainrings, and chain. In order to achieve this performance, you'll need to find the shoes that best adapt to your needs in function of the modalities that you practise.
One of the main aspects to evaluate of a cycle shoe is its weight. Using heavy shoes requires a greater effort in our pedalling and therefore lower performance. But obviously we mustn't neglect protection and therefore it is necessary to find the optimum ratio between weight and protection.
The inside of a cycle shoe must have a suitable breathability. The foot is in continuous movement whereby the moisture generated by the sweat can end up generating a greater sensation of cold due to poor ventilation. Of course, no matter how good the shoe is in this aspect, we need the sock for adequate breathability.
The hold and rigidity are other important points. To feel that the shoe has the appropriate hold gives us confidence to apply all the force required to the pedals in order to move the bike. The fastening systems also influence the way we use the force. You'll find different systems like, for example, via Velcro straps, a plastic micrometric fastener or a combination of the two. For the more purist cyclists there are some with laces and a retro design.
The sole is a very significant part of the cycle shoe, as it is the main difference between the footwear of each modality. In function of the cycle modality that you practise, you'll need one type of cleat, or another depending on whether the type of pedal is flat or not. The studs, mainly for mountain and cyclocross bicycle shoes, which provide optimum traction on those stretches that force you to get off the bike.
Lastly, as a complementary element, you have over shoes to fight the cold and rain. Also known as booties, there are two types: completely covering the shoe or those that just protect the toes.