Monday, August 11, 2008

203.6 miles Flat Front Tire!

When I went down to the basement tonight I noticed that my front tire was flat. This is the same one that I fixed on March 22, 2008 after only 31.8 miles. To put it in perspective, I have over 1700 miles on my Raleigh Grand Prix road bike and have not had a flat.

When you fix a flat you need to determine what caused the flat or it will just happen again. Also I usually just replace the tube rather than do a repair since tubes are inexpensive ($5).

I carefully removed the tube from the tire then investigated the possible causes. Here are my findings :

1.) Leaking valve : with some pressure in the tube I placed the tube in a bucket of water. No bubbles were coming from the valve. This was not the cause. There was about 1 bubble every two seconds coming from the tube 90 degrees from the valve stem location.

2.) An external object punctured the tire and tube: At the location of the leak there were no objects on or in the tire. I also checked the entire inner and outer surface of the tire, there were no objects. This was not the cause.

3.) A sharp point on the rim or a spoke poking through the rim tape punctured the tube: The rim tape was intact. There were no sharp points on the rim. This was not the cause.

4.) A tube manufacturer's defect: The defect is right on the seam. I believe this is the cause.

The tube was a Nashbar serial # 20126601 made in Taiwan tube. The replacement is from PricePoint. The markings on the replacement tube are CST 05127111 made in China. CST is Cheng Shin Tire which was actually the manufacturer of the original tube I replaced in March. They may also be the manufacturer of the Nashbar tube. I googled Cheng Shin and found that they are the 12th largest rubber manufacturer in the world. They go by the name of Maxxis in the United States.

I will see how this replacement performs. If I get another seam defect I will start buying better quality tubes.

No comments: