Flex Grooves Explained

In brief: Flex grooves are cuts or channels in the outsole and midsole that control where and how easily a running shoe bends, tuning flexibility and ride.

What are flex grooves?

Flex grooves are deliberate grooves cut into the bottom of the shoe, across or along the sole. By removing material in specific places, designers control exactly where the shoe bends. They are most visible as the deep horizontal lines across the forefoot of many trainers.

What they do

Flex grooves let the sole bend smoothly with your foot, usually at the ball of the foot where you toe off. This keeps the shoe from fighting your natural motion and can make a ride feel more flexible and connected. Lengthwise grooves can also let the shoe adapt to uneven ground. Their placement is matched to the foot's natural flex point.

Types and variations

Patterns vary from a few deep transverse grooves to a fine grid of segmented pods. Flexible, natural-feel shoes use many grooves; stiff, plated racing shoes use few or none because the plate is meant to resist bending. Trail shoes balance flex grooves against the need for underfoot protection.

What to look for

If you like a flexible, natural ride, look for defined forefoot flex grooves. If you prefer a stiff, propulsive feel, a plated shoe with few grooves suits better. The grooves should align with where your foot naturally bends, not force a bend elsewhere.

Flex grooves and your running kit at OD's

Flexibility is a big part of ride feel. We can help you compare flexible and stiff shoes across our range, with next-day delivery and free click and collect.