A sole structure for an article of footwear includes a midsole having a medial edge and a lateral edge. The sole structure also include a first lower rib extending from the medial edge to the lateral edge of the midsole. The first lower rib includes a portion spaced from the midsole between the medial edge and the lateral edge. The sole structure further includes a medial flex member disposed between the midsole and the first lower rib near the medial edge and a lateral flex member disposed between the midsole and the first lower rib near the lateral edge. The medial flex member and the lateral flex member are configured to flex the first lower rib relative to the midsole in response to a force of a predetermined magnitude.