Kind remain-- 1.Please kindly check the size of your bicycle tire before you buy. If you buy tubes are not the right size, you may return the products for a full refund. 2.Before changing the tube, please check whether have some stones or sharp things that may broke the tube that stay in your tire. 3.Remember to always add a little air (to give the tube form) to the new inner tube before installing. This will prevent it from bunching up and/or causing a pinch flat or possibly blowing the tire off the rim (when you immediately and fully inflate) which ultimately will pop the tube. 4.Never over inflate past the recommended tire pressure.