A back support for a chair includes a cover configured to be coupled to opposing sides of a chair frame. A strap is connected to the cover. A sled having a central portion is coupled to the strap, the sled is configured to pivot with respect to the chair frame and provide support to a user's back. The cover is configured to moveably connect to the chair frame between a low position and a high position. The sled is configured to pivot as the cover moves between the low position and the high position so that the central portion of the sled is substantially parallel to at least a portion of a membrane connected to the frame between the low position and the high position.