Do not buy too small shoes

Adam Ondra has a regular shoe size of 44 but his La Sportiva are normally 39, see the picture! The trick he uses, when they are brand new, is to squeeze them in by putting the heal and toes inside the plastic paper that goes with the shoes. At the same time, being challenged on on slab volumes in bouldering comps, he has said that the size does not matter and some slabs he could equally well be doing in his sneakers. The reason for this is that you do not want the ballerina feeling on such volume slabs as you instead want as much even friction as possible. However, normally all the top climbers are eager for doing the Geisha trick and this has caused a lot of pain for the regular climbers.

Training indoors standing mainly on bigger holds, it is counter productive for all below 7a to use tight painful shoes. If you want to build up your toe strength, it is actually better to climb in bigger very soft shoes and now we are talking shoes you do not have to take off after each climb. Once you get more advanced, you can buy also a tighter size but them you should only be using outdoors or when challenging yourself bouldering on small foot holds. A further disadvantage with small shoes, beside the pain and that you do not train your toes equally much, is that they wear out faster as all your weight is stressed on a smaller sweet spot of your shoes.