Tubes Flat on Inside Radius

[Sparky]

I recently had a problem with a couple of tubes that went flat, but not from punctures. Both tubes appeared to have tears in them on the inside radius next to, and parallel to some mold flashing. The tears are about 1mm long. They were both mounted on the front wheel of my mountain bike.

The proximity of the tears to the mold flashing makes me suspect the quality control by the tube manufacturer. The fact that they were both on the same wheel makes me suspect the wheel. The wheel had rim tape that was a rather flimsy piece of rubber that looked like it could easily be pushed out of position and allowing the tube to expand into one of the spoke nipple holes, resulting in the tears that I have observed. Based on this theory I have replaced the rim tape with a Velox cloth tape.

Has anyone else had a similar experience with tubes getting flats on the inside radius of the tube? I apologize for the long post, but this has been a really vexing problem.

[DaveM]

Yes, this is quite common. Usually either from rim tape that moves around or is too thin. Also can be caused by rough spots on the interior of the rim surface, sharp edge on the valve stem hole, etc. It's often helpful to pay attention to where the hole in the tube was in relation to the wheel. That will help you find the spoke that's not fully covered, the thorn in your tire, etc.
Faulty tubes exist, but are very rare.

[froze]

Be safe and replace the rim tape with a quality cloth tape, just make sure the tape you select will fit your rim. While your replacing the rim tape check the rim for rough spots that could flatten a tire, but I don't think that's your problem.