Abstract: A folding handlebar includes a stem, a pair of handles pivotally connected the stem, an abutting member, and a clamping device. The stem includes a fixing portion having a first abutting face, and an extending portion having a receiving space interconnected to a first bore. Each handle includes first and second joint faces. The abutting member includes a second abutting face abuttable against the first abutting face and one of the first and second joint faces, and a second bore aligned with the first bore. The clamping device includes a rod assembly inserted into the first and second bores, a fastener received into the receiving space and engageable with the rod assembly, and an eccentric member abuttable against the abutting member to selectively abut against the stem for providing a reliable engagement between the abutting member and the stem.