虫ゴムの寿命は1年だそうです。これからは、1年をめどに交換しようと思います。電車に乗り遅れたくないですから。
My bicycle had got a flat tire. Checking a valve rubber, I found the rubber changed in quality. After it was replaced with a new one, the air of the tire did not loose. The rubber tube did not have the problem.
They say the life of the valve rubber is about one year. From now on, I'll replace it annually. I do not want to miss the train.
upper: damaged rubber
below: replacement parts
