A double-cogged V-belt with the upper and lower cog profiles symmetric and having lines (“L”) and arcs (“A”) connected according to a sequence from the center of a root to the center of an adjacent cog of L1-A1-L2-A2-L3 for the upper profile and L4-A3-L5-A4-L6, and with at least one upper root and one lower root substantially aligned with each other, and with the sum of the length of L1 plus the radius of A1 equal to or within 20% of the sum of the length of L4 plus the radius of A3. The upper and lower pitches may be equal and all the roots aligned, or there may be more upper cogs than lower cogs. Some or all arcs and lines may be connected tangentially.