Review: Anti-Flat Bicycle Tire Sealants

Flat tires are the best way to ruin your day. I’ve written an article on six ways to avoid flat tires, and one of the best methods included the article is to use a bicycle tire sealant.

Bicycle tire sealants are basically a set it and forget it solution to flat tires on your bike. You simply fill the tube with a measured amount of sealant, re-inflate it and move on. The sealant automatically spreads out inside the tube to coat the entire outer surface. If (or more likely when) something punctures the tire and tube, the sealant is forced into the hole and plugs it, keeping any more air from escaping.

Well, that’s how it works in theory. It’s not a 100% perfect system, but I’ve still found it to be highly effective at preventing flat tires.

I’ve used a number of different brands of bicycle tire sealants over the years. Each one has its own way of working and can be better in some situations more than others. Here I will review three of my favorite bicycle tire sealants so you can see how they might be appropriate for your own electric bicycle.

Bicycle tire sealant: Green Slime

Green Slime is perhaps the most famous tire sealant. It’s not just meant for bicycles either; lots of people use it in everything from cars to trailers to ATVS. It’s a great all-around tire sealant and works wonders on bicycle tubes.

Green Slime is a fibrous type of sealant, meaning its got lots of little fibers suspended in solution. The appearance is, well, like what you’d imagine a product called Green Slime to look like. Most bottles come with a valve removal tool in the cap to make installation easy. You simply use the cap to unscrew the valve from inside the valve stem of your bicycle tube, squirt in a liberal amount of slime, then insert and close the valve with the supplied tool again. This can be done either while the tube is installed in the bicycle or before you even use the tube while its still outside of the bike.

I’ve found Green Slime to be a better bicycle tire sealant for punctures made by odd shaped objects like screws or wood splinters. Basically anything that makes a jagged hole has been fairly well sealed by Green Slime in my opinion. I’m not positive, but I think the fibrous nature of Green Slime helps it seal nonuniform shaped holes better than some of the other products out there.

The downside of Green Slime is that it isn’t a very long term fix. From my experience I’ve found that while Green Slime will usually plug a hole, it will last a matter of days, not weeks or months. Green Slime makes more of a physical barrier when it plugs a hole, unlike some of the other bicycle tire sealants we will cover next. For this reason, Green Slime is more of a temporary solution. When you notice you’ve got a little Green Slime on your tire and see a screw hanging out, it’s time to head for your garage or local bicycle shop. The Green Slime will likely hold for a while to get you back safely, but it’s not meant to be able to drive around on continuously.

Bicycle Tire Sealant: Joe’s Super Sealant

Joe’s super sealant is installed in a similar way to Green Slime, but usually doesn’t come with the installation tool needed to remove the valve from the valve stem. You’re on your own there.

Joe’s super sealant is also a fundamentally different type of sealant. While Green Slime is a more fibrous sealant which forms a temporary physical blockage, Joes tire sealant is more a rubbery glue-like material. When exposed to air, it hardens into this nasty, sticky compound that is perfect for sealing holes in bicycle tubes (but a pain to remove when you get it all over your hands).

For this reason, Joe’s tire sealant is better at sealing smaller, more uniform holes. Larger jagged holes are tough to seal because of the large surface area involved, but smaller and more uniform punctures are easily filled with glue and sealed.

In my experience, I’ve found that Joe’s super sealant can be a longer term fix than Green Slime. I once had a thumb tack puncture my tire and the hole was instantly sealed by the Joe’s tire sealant. I was busy at the time and kept putting off replacing the tube. Days turned into weeks and I was surprised to see the seal was still holding up fine. I decided to see how long the fix would last. It wasn’t until 8 months when I slipped on wet pavement and went skidding along the ground that the repair finally gave way. The force of the crash caused the tack to shoot out of the tire and a good amount of the Joe’s super sealant came with. Even so, the leak was slow enough that I still was able to ride the 4 miles back to home while slowly bleeding air pressure. At that point though the Joe’s super sealant was well over a year old, and they do recommend replacing the sealant when it ages. Adding more every 6 months is a good ballpark.

Bicycle Tire Sealant: Stan’s NoTubes Tire Sealant

Stan’s NoTubes Tire Sealant is similar to Joe’s Tire Sealant, though it is meant for tubeless bicycle tires. Tubeless tires, like the name implies, don’t have an inner tube. Instead, the bicycle rim is sealed and the tire seals with the bead against the rim, similar to a car tire.

Stan’s sealant is fundamentally similar to Joe’s sealant. They are both a glue-type of sealant that fills holes and dries to seal the hole while preventing air from escaping. Check out this promotional video – it’s hard to believe this is even real!

Just like Joe’s, you’ll want to make sure you top off your tires occasionally to keep the sealant from drying inside. Every six months is a good figure to use.

Even though Stan’s NoTubes Tire Sealant is designed for tubeless tire systems, you can use it in an inner tube just as well, and it will have the same sealing effect.

Bicycle tire sealants: the verdict

Bicycle tire sealants are a must-have for anyone who hates dealing with flat tires, which basically means everyone. All three of the tire sealant systems covered above work great, but I’m partial to Joe’s myself, mostly because I’ve used it the most and thus had the most experience with how well it works.

All three of these will be great for you though and help you get home even after a big puncture in the middle of a ride. Green Slime is more of a temporary solution, while Joe’s and Stan’s can be more permanent fixes. I’ve even used tire sealants to fix a flat tire before in a pinch when I didn’t want to through the whole process of removing the wheel and changing the tube. If you didn’t have a tire sealant in the tube to begin with, just pump some sealant in there after you’ve got a flat, re-inflate, and there’s a good chance your flat will be fixed.

Like I said before, nothing is 100%, but this is about the best you can get without going with fancy foam tires or other new methods to completely remove the chances of flats.

photo credit 1, 2, 3