A hydraulic disc brake master cylinder having a bar clamp attached to a master cylinder housing allowing the attachment of the master cylinder to a handle bar along a longitudinal clamp axis. The master cylinder also includes a cylinder wall associated with the master cylinder housing extending axially along the cylinder axis. The cylinder axis is not parallel to the longitudinal clamp axis. This embodiment further includes a reservoir for hydraulic fluid which includes a first wall which first wall includes only a radial portion of the cylinder exterior. The reservoir also includes an elastomeric diaphragm. The cylinder axis and the longitudinal clamp axis lie in a plane substantially bisecting the first wall. Thus, the symmetric master cylinder lever may be disposed on either the right or left portion of a handle bar without effecting operation of the master cylinder lever by a user.