How to choose a daily running shoe

A daily trainer is the shoe you do most of your running in, which means it is judged on what it does not do. It should not be the reason a run goes badly, it should not need thinking about, and it should still be there in six months. Almost every disagreement about which one to buy comes down to four specifications.

Drop decides where the load goes

Drop is the height difference between heel and forefoot, quoted in millimetres. It changes where load goes: a higher drop shifts work away from the calf and Achilles and towards the knee, a lower one does the reverse. Ten millimetres is the traditional daily-trainer figure and four to six is common on newer shoes. There is no correct number for everyone, but there is a correct way to change it. Moving abruptly from a ten to a four is one of the more reliable ways to give yourself a calf problem, and the shoe will get the blame.

Stack height and weight are a single trade

Stack height is how much foam sits between your foot and the road. More foam means more cushioning and, almost always, more weight. Somewhere above forty millimetres it also starts to cost stability, which matters more on uneven ground and to heavier runners than the marketing suggests. If you run on pavements and canal paths, high stack is a comfort feature. If you run on trails and camber, it is a trade.

Weight is the number people over-weight in their decision, if you will forgive the pun. On easy runs, thirty grams is not something you can feel. On a long run at pace it is. Under 250 grams in a US 9 is light for a daily trainer, over 290 is heavy, and most of the difference goes into either foam volume or outsole rubber — both of which buy you durability.

The fourth number is the one nobody publishes: how long the midsole holds its properties. Manufacturers quote outsole durability because rubber is easy to measure and slow to wear. The foam above it degrades earlier and far more quietly, which is why a shoe with plenty of tread left can still feel flat and lifeless. As a rough rule, the softer and lighter the foam, the sooner it goes. A firmer, heavier shoe that lasts 800 kilometres is often cheaper per kilometre than a light one that is done at 400.

Fit overrules all four numbers

None of this beats fit, and fit cannot be read off a spec sheet. Width, instep volume and heel shape vary enormously between brands, and they change between generations of the same model. If a shoe has ever given you pressure across the midfoot, check whether the maker offers a wide fitting before you conclude the model is wrong for you — several do, and most shops do not stock them.

The practical order to work in: decide your drop from what you already run in, pick a stack height that suits your surfaces, treat weight as a tiebreaker, and then let fit overrule all three.