An Eccentric Bottom Bracket (EBB) is a device used to add tension to a bike chain or belt. A traditional bottom threads into an EBB in an off center location, which allows tension to be increased or decreased by swiveling the EBB clockwise or counterclockwise. When the appropriate tension is achieved, the EBB is held in place by expander bolts inside the unit.
The EBB adjusts chain tension at bottom bracket, allowing the frame to have traditional horizontal drop outs.
$400 per frame.