I bought this crank set for my son, who is 13 yrs old and 106 lbs. He had a minor fall at the BMX track and one of the crank arms bent, enough so that it hits the chainstay. Nobody at the track has ever seen a crank bend before for a similar fall. Very surprising. I tried contacting Promax, but they have not responded to my emails and don't reply to voicemail either. Cheaply made parts with no support. Do not buy. Update: After several calls and several days Promax finally returned a call. They said it was not unexpected that the crank would bend in a minor fall. They had me send it back to them to evaluate (at an added cost of $13), but after evaluating they only offered to sell me a replacement a a discounted price. I declined the offer as apparently this is the expected quality level of their parts.