An article of footwear suitable for receiving a removable insert (152, 154), comprising: an upper; a sole structure comprising a midsole, the midsole having: a front peripheral portion; a rear peripheral portion; a first side peripheral portion extending between the front peripheral portion and the rear peripheral portion; a second side peripheral portion extending between the front peripheral portion and the rear peripheral portion, the second side peripheral portion being disposed on an opposing side of the midsole from the first side peripheral portion; a top portion and a bottom portion; a cavity; wherein the cavity has a first cavity sidewall associated with the first side peripheral portion and wherein the cavity has a second cavity sidewall associated with the second side peripheral portion; wherein the cavity has a lower cavity surface associated with the bottom portion; and wherein the first cavity sidewall is tapered and wherein the second cavity sidewall is tapered, wherein a first lower peripheral portion of the upper is attached to the first cavity sidewall, and wherein a second lower peripheral portion of the upper is attached to the second cavity sidewall, wherein the lower cavity surface is approximately parallel with a ground contacting surface of the article of footwear, wherein a first angle formed between the first cavity sidewall and the lower cavity surface is in a range between 100 and 150 degrees, wherein the first cavity sidewall is approximately linear in shape and wherein the second cavity sidewall is approximately linear in shape. an upper; a sole structure comprising a midsole, the midsole having: a front peripheral portion; a rear peripheral portion; a first side peripheral portion extending between the front peripheral portion and the rear peripheral portion; a second side peripheral portion extending between the front peripheral portion and the rear peripheral portion, the second side peripheral portion being disposed on an opposing side of the midsole from the first side peripheral portion; a top portion and a bottom portion; a cavity; a front peripheral portion; a rear peripheral portion; a first side peripheral portion extending between the front peripheral portion and the rear peripheral portion; a second side peripheral portion extending between the front peripheral portion and the rear peripheral portion, the second side peripheral portion being disposed on an opposing side of the midsole from the first side peripheral portion; a top portion and a bottom portion; a cavity; wherein the cavity has a first cavity sidewall associated with the first side peripheral portion and wherein the cavity has a second cavity sidewall associated with the second side peripheral portion; wherein the cavity has a lower cavity surface associated with the bottom portion; and wherein the first cavity sidewall is tapered and wherein the second cavity sidewall is tapered, wherein a first lower peripheral portion of the upper is attached to the first cavity sidewall, and wherein a second lower peripheral portion of the upper is attached to the second cavity sidewall, wherein the lower cavity surface is approximately parallel with a ground contacting surface of the article of footwear, wherein a first angle formed between the first cavity sidewall and the lower cavity surface is in a range between 100 and 150 degrees, wherein the first cavity sidewall is approximately linear in shape and wherein the second cavity sidewall is approximately linear in shape.