The Yepp Mini seat is always packed including a standard handlebar adapter. In case this doesn’t fit your bike, this threadless or A head handlebar adapter needs to be purchsased seperately. The threadless Yepp Mini adapter requires a regular front fork (steel) with a diameter of 11/8 inch.. Please note: Use the Yepp products only on a bicycle that is in good working order and of the type suitable for carrying the additional load. Contact the bicycle manufacturer to obtain this information.