With so much accuracy in performance and mechanical adjustments related to cycling, it’s curious that the same isn’t true for the volume of tire sealant. There are suggestions on sealant bottles. But at best, they are very rough estimates of what amount of sealant will cover the entire interior surface of the tire and have enough left over to seal punctures.
Tubeless bicycle tires have been around for 25 years. During that time, countless technological advancements have rocketed high-end cycling into the stratosphere. Carbon fiber, electronic drivetrains, power meters, GPS-enabled cycling computers, ceramic bearings, and sweat sensors have all made their debut or become normal.
Cyclists commonly use tire pressure calculators, which are available online from brands like SRAM and Silca. These take into account tire width to the millimeter, rider weight, type of riding, and riding surface.
However, there is no such tool for tire sealant volume.
Every bottle I have at home has a wide range for both the tire width and volume. “23-60mm” for tire width is such an expansive width; the same is true for 60-90mL for volume. Some bottles only delineate between bike types, like MTB versus road tire.
But James Huang, at the Substack account N-1, has filled the gap in cycling’s penchant for high-resolution everything. He has developed and made a publicly accessible tire sealant calculator.
Bicycle Tire Sealant Calculator: How It Works
Huang, who has been a cycling journalist for decades, possesses an incredible wealth of cycling gear and industry knowledge. His explanation of how he “programmed” the calculator displays his grasp of things I’ve long forgotten since college.
We all understand the general shape of a bicycle tire, but to the smarter types, it’s mathematically a toroid. Without dumbing it down too much, this is effectively a “donut” shape — a circle with a hole in the middle. According to Huang, plentiful formulas related to toroids exist.
“You can just take the surface area of that toroid and then multiply it by a desired thickness of sealant throughout the interior,” Huang explained. “This doesn’t quite reflect reality, since sealant isn’t perfectly distributed across the entire interior surface area of the tire and rim, but for our purposes, it nevertheless spits out a useful figure.”
How Much Sealant Should You Use?
Huang’s Substack article about his tire sealant calculator discusses other variables that could affect the calculation. These include exact tire and rim shapes and differences between the effectiveness of different sealants.
In the end, Huang concludes, “This calculator isn’t designed to address all of those variables, but I’ve tweaked it so that it reliably provides a good starting point no matter what width or diameter of tire you’re running. Feel free to adjust the recommended amount slightly for your particular wants and needs, but you shouldn’t need to go up or down more than about 10%.”
Regardless, this calculator is vastly more accurate than the guess-and-pour method I’ve used forever. It will also save money and grams. I always poured heavy instead of risking being short. I didn’t want to worry about the sealant not working in the event of a puncture (which always seems to happen far from home, in the rain).
Download Huang’s tire sealant calculator and know with mathematical accuracy that you have the correct amount of the good stuff splashing around in your tires. This is a Google Sheet, so you will have to save it to your own local drive before use, and it’s not available as a standalone iPhone app. Once you have it on your own Google Drive, simply enter the rim diameter and tire width, and presto, Huang’s calculator spits out the mathematically derived tire sealant volume.
Read the full article here
