Sheet feeding device and image forming apparatus incorporating same

A sheet feeding device includes a support, a rotation driver, a guide, a support shaft, a biasing member, a leading end sensor, a roller, an outer diameter sensor, and circuitry. The circuitry causes the rotation driver to rotate a spool in a winding direction to determine a timing at which a signal change rate exceeds a change rate threshold as a passing time at which a leading end of a continuous sheet passes through the leading end sensor, causes the rotation driver to rotate the spool by a rotation angle in the winding direction, from the passing time, to position the leading end of the continuous sheet at a feeding start position, and rotates the spool in a feeding direction to feed the continuous sheet from the feeding start position along a guide portion. Further, the circuitry changes the change rate threshold based on an outer diameter of a roll.