Taking SCARY out of used bikes, one bike at a time.
There many reasons to get multiple flats, and this is one of them.
Rim tape failure. This is when your rim tape sides over and exposes the spoke holes of the rim. When you’re talking about 60-120 pounds per square inch (PSI) it can easily cut the tube from the inside.
How does this happen? Just by fixing the flat the rim tape can move over is the most common reason. Or the tape was not installed correctly and maybe it’s the wrong width that doesn’t have good coverage.
So what is the fit? There are many rim tape brands out there and some are good and some are NOT. But for the basic tube rim (not tubless or high end custom rims) the industry goes to is Velox tape. It works very well and last for years. Just make sure you get the right size width, you want your tape to cover the whole rim cavity to insure it doesn’t side and will hold up to the pressure.
So to install I would pull the old one out (don’t reuse or cover up) and clean the inside of the rim with rubbing alcohol. Let it dry and carefully lay the new (Velox) tape over the holes. Make sure the tape has a firm tension and press firmly to insure there is no bubbles under the tape. For the tube valve stem you can use a hole punch or ice pick.