Before you start you will have to cut the valve off and wash the tube. The best way to do so is with soapy water. Then measure your bike tube and cut it to the correct length. Remember to add about 6-7 cm to attach the belt buckle later.
Sewing a bike tube is surprisingly simple. If your machine is having problems, simply add a small layer of oil on top of the tube. I used a straight stitch and after I was all the way around tried it strength. I noticed that the stitch was to weak and I was able to tear it apart.So I added an other stitch next to it, as shown in the pictures. I used super glue to prevent the stitches from opening.