Flat Stopper Tubeless Bike Tire Sealant Claims 1-year Lifespan, Doesn’t Ball Up

The Flat Stopper is a natural tubeless bike tire sealant made from water, minerals, and fibers that lasts a year or more without drying out.

photo: Greg Heil

Flat Stopper tire sealant has been used in tires for off-road and farm vehicles for several years. Now, the company is packaging and marketing the product for mountain bike tires, and based on the company’s claims, the product seems to have some advantages over existing bike tire sealants.

Latex bike tire sealants currently on the market typically claim a 3-month lifespan before the liquid dries up inside the tire and is no longer effective. In contrast, Flat Stopper claims a useful life of a year or more. Not only that, Flat Stopper does not “ball up” inside the tire as it dries out, making it easy to keep valves and the inside of tires clean.

The Flat Stopper formulation appears to be unique as well. Bike shops can purchase the dry material in bulk and add water to create the sealant. The sealant itself is natural, consisting of a mixture of minerals and “a particular fiber commonly found in clothing.” One of the included minerals is mica, which looks like glitter in the solution.

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For mountain bike tires, Flat Stopper recommends adding 3.5 ounces of liquid for maximum protection. Competing latex-based sealants often recommend using just 2 ounces, but some riders do opt to use larger amounts for high-volume tires or for aggressive riding.

Finally, the Flat Stopper is being packaged in a unique clear package with a cap that’s ready-to-use with any removable-core tire valve. Throw one in your pack and tell you riding buddies it’s a blood bag to use in case of emergency.

Look for The Flat Stopper to be sold in select local bike shops soon.