Punctures are one of life’s pains. Thankfully there are tire sealants out there that are designed to repair a puncture as it happens to help keep you rolling. There are two broad types of tire sealant products, those that are injected into a tire before a puncture and sit within the tube and work to stop a puncture from deflating your tire, and those that use a mixture of sealant and gas to both inflate your tires after a puncture, and seal them in one go. We look at the most popular sealants on the market and whether they do what they advertise.
These are sealants that are inserted into the tire before a puncture. The sealant can be either poured into the tubeless tire when mounting, or injected through the valve of a tube. The injecting is best done with the valve core removed to prevent clogging the valve. Latex based sealants however can be injected through non-removable presta valves without fear of clogging up your valve. The sealant material is distributed evenly throughout the inside of the tire and stays in liquid form until a puncture forces the material through the hole, at which point the liquid solidifies and stops the puncture from leaking out all the air. The most famous brand on the market in this category is Stans No Tubes. This latex based sealant makes it possible to turn standard tires that contain an inner tube into full tubeless setups with the use of their rim-sealing tapes and rim stripes, something that has become incredibly popular in mountain biking. Stans No Tubes is famous for being able to seal larger punctures through the tread, and multiple punctures. The major disadvantage with this system is that given enough time, the sealant will eventually harden and stop being effective. At this point in time, you need to remove your tire and clean the gunk off the inside. If you injected the sealant into an inner tube, you may need to replace your inner tube. Removing the solidified sealant is both a time consuming, and messy process.
Sealant/ gas combo
These sealants are primarily designed to be used after a puncture. The gas cartridge contains carbon dioxide to inflate the tire, as well as a sealant to seal the puncture. The advantage of these products is that there’s no sealant within the tires before a puncture, reducing the rotational weight of the bicycle, and ensuring your sealant is fresh when you need it. A point to make with this setup is that you need to be careful when using this gas cartridges as there is one horror story where a guy from a club I won’t mention went through two cartridges of sealant before he could get enough product into the tire to seal the puncture. By the end of it all, he looked more like Santa Claus with his white hands and face than anyone else.
Three of the most popular brands of sealants with gas are:
Michelin Stop & Go tire sealant
A CO2 and latex based sealant combination that that is used to seal and inflate tires after a puncture.
Hutchinson Fast ‘Air
An aerosol containing foaming latex based sealant. Inject the sealant using the attached flexible tube. Can be used to both seal and inflate a tire.
Vittoria Pit Stop
An aerosol containing foaming latex based sealant. Inject the sealant using the nozzle. Can be used to both seal and inflate a tire.
We tested the two styles of tire sealants to see whether they work. For the test, we used a road bike equipped with 23mm wide Continental GP 4000 tires pumped to 110psi. We used a normal 4mm wide screw to puncture the tire.
Stans No Tubes
After puncturing the inner tube and a few seconds of hissing and a little goo, the sealant did its job. There was a pressure loss of 32psi. Stans No Tubes make the claim that the product will seal multiple punctures. We repeated the process and found that the goo sealed the inner tube again. The second puncture resulted in a pressure drop of 29psi. With on puncture, you still have enough pressure in the tire to limp home. If you suffer from a double puncture, you will need to top up your tires to get home.
Michelin Stop & Go tire sealant
Repeating the process with a clean inner tube and fresh hole, the Michelin Stop & Go sealant was able to seal the puncture and inflate the tire to 105psi. There was more hissing and sealant that escaped the puncture before the hole was finally sealed. A final pressure of 105psi would be more than enough pressure to ride a bicycle normally, however if your running bigger tires or mountain bike tires, this might not be enough pressure and you would need to top up with either a pump or another carbon dioxide canister.
It was a surprise that the tire sealants were able to seal the punctures as quickly as they did. In the real world hours from home, you can count on these systems getting you home in the case you do run over debris and puncture.