distance between front roller and rear 2 is adjustable to account for long / short wheelbase - no sure if goes down far enough for kids bikes...also, distance between rear 2 rollers is non-adjustable...have no idea how would ride on 24" wheel...my instinct says fine but never tried ...am happy for you to take them and see if they are ridable - if not bring them back
distance between front roller and rear 2 is adjustable to account for long / short wheelbase - no sure if goes down far enough for kids bikes...also, distance between rear 2 rollers is non-adjustable...have no idea how would ride on 24" wheel...my instinct says fine but never tried ...am happy for you to take them and see if they are ridable - if not bring them back