More information would help. Is this a disc brake front wheel? With the front wheel removed, measure the distance (in millimeters) from the outside (between) the existing axle lock nuts (these hold the spacers and threaded hub cones in place. Then measure the thickness (in millimeters) of the fork blade through which the axle must pass. The correct length of axle is (locknut-to-locknut outer dimension) plus (2 x fork blade thickness), less two millimeters (approximately).