Fits most 21 inch front tubed tyres and many use it as an emergency spare on their rear wheels to get them home. When was the last time you changed the spare 21 inch tube you have been carrying around on your bike. It will be essential one day that a standard tube will be used in either the front or the rear wheel of your bike to get you home and you will hope that it holds air. Whether it is just old and starting to perish or it is thin in places from rubbing on other gear it could be time to throw it out and drop another new one in its place. It is very cheap insurance. On its own it will be $9.00 postage. Ordered with other gear that attracts a postage charge is will be free. Just click on the item to create an order.