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Challenge Smart Tubeless Sealant



Works on a range of tyres and pressures, while lasting for months at a time
Quick sealing
Works on large cuts too
Cheaper solutions out there that work well

At every product is thoroughly tested for as long as it takes to get a proper insight into how well it works. Our reviewers are experienced cyclists that we trust to be objective. While we strive to ensure that opinions expressed are backed up by facts, reviews are by their nature an informed opinion, not a definitive verdict. We don't intentionally try to break anything (except locks) but we do try to look for weak points in any design. The overall score is not just an average of the other scores: it reflects both a product's function and value – with value determined by how a product compares with items of similar spec, quality, and price.

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The Challenge Smart Tubeless Tyre Sealant works well on a whole range of tyres, from high-pressure road hoops to big, low-pressure gravel rubber, and seals cuts big and small. It doesn't seem affected by temperature changes either.

Challenge has developed its Smart Sealant to work with both vulcanised and handmade tubeless tyres, and I tested it on both with no setup issues. With a pair of Challenge's handmade gravel open clinchers I had to ride a few miles to get the sealant to completely coat the tyre and fully seal, and while that's due to the construction of the sidewall, it does demonstrate that the sealant works.

Have a stab at it

Challenge claims it can seal cuts up to 6mm, which I'd say is realistic. As is often the way I didn't puncture naturally, so instead I used a knife to cut the tyre with slits of various sizes. I found the sealant worked quickly, even on road tyres running pressures up around 70psi.

Some sealants can struggle at anything above 50psi, but there were no issues here.

Challenge doesn't go into detail about what is actually in this stuff (although they do say want isn't – like ammonia), but by the looks of it there are small particles in there too, which most likely join together to seal larger gaps.

I've used Challenge's Smart Sealant before so I can vouch for its longevity. They say six months and I'd say that's about right. Obviously it depends somewhat on the ambient temperature, and I was using it during the record temperatures of summer 2022, which meant it did dry out a bit quicker than expected.

You can top it up through the valve though, which you can with sealants featuring large particles for sealing holes.


A 250ml bottle costs £15, which works out at 6p per millilitre. That's cheaper than the Pirelli Cinturato Sealant, and Challenge doesn't stain everything yellow when you spill it, either.

The Finish Line FibreLink Tubeless sealant is similarly priced at 5.4p per millimetre, and Steve was impressed overall with its performance.


Smart Sealant does exactly what it claims to, offering good sealing against punctures and a good service life too.


Works on a range of tyres and pressures, while lasting for months at a time test report

Make and model: Challenge Smart Tubeless Sealant

Size tested: 250 ml

Tell us what the product is for and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about it?

Challenge says, "High performance tubeless systems deserve high-performance tubeless sealants. The SMART Sealant was designed to work with both vulcanized and handmade TLR and Tubeless tires. This non-allergenic, ammonia-free formula can seal up to 6mm cuts, remains liquid in the tire for up to 6 months, doesn't coagulate with Co2 use, and doesn't damage rims or tires with extended use. Installation is straightforward using the application tip and there is no need to shake the bottle. Available in a 250ml/8.5oz bottle."

It works efficiently and is reasonably priced.

Tell us some more about the technical aspects of the product?

Seals up to 6mm cuts

Doesn't damage rims or tires

No need to shake

Remains liquid in the tire for ~ 6 months

Keep adding as needed through the valve

Doesn't coagulate with Co2 use


Rate the product for performance:
Rate the product for durability:
Rate the product for value:

Tell us how the product performed overall when used for its designed purpose

It sealed a range of hole sizes, at varying pressures.

Tell us what you particularly liked about the product

Works at higher pressures, unlike some.

Tell us what you particularly disliked about the product

Nothing really stands out.

How does the price compare to that of similar products in the market, including ones recently tested on

It sits somewhere in the mid-range when compared to others we've reviewed.

Did you enjoy using the product? Yes

Would you consider buying the product? Yes

Would you recommend the product to a friend? Yes

Use this box to explain your overall score

It works effectively and achieves the claims on the bottle, for a decent price.

Overall rating: 7/10

About the tester

Age: 44  Height: 180cm  Weight: 76kg

I usually ride: This month's test bike  My best bike is: B'Twin Ultra CF draped in the latest bling test components

I've been riding for: Over 20 years  I ride: Every day  I would class myself as: Expert

I regularly do the following types of riding: time trialling, commuting, club rides, sportives, fixed/singlespeed,

As part of the tech team here at F-At Digital, senior product reviewer Stu spends the majority of his time writing in-depth reviews for, and ebiketips using the knowledge gained from testing over 1,500 pieces of kit (plus 100's of bikes) since starting out as a freelancer back in 2009. After first throwing his leg over a race bike back in 2000, Stu's ridden more than 170,000 miles on road, time-trial, track, and gravel bikes, and while he's put his racing days behind him, he still likes to smash the pedals rather than take things easy. With a background in design and engineering, he has an obsession with how things are developed and manufactured, has a borderline fetish for handbuilt metal frames and finds a rim braked road bike very aesthetically pleasing!

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huntswheelers | 1 year ago

I had to go to Challenge to find out whether it was Latex or non Latex and it's a Latex job. I had a customer come in for wheel bearings and asked me to change the sealant. The customer had been using a so called "Top brand" latex based sealant and the tyre was a mess inside, the sealant had damaged the tyre inside and it had absorbed sealant like a sponge, so much so the side walls stuck as if it was rubber solution glue at the tacky stage. I cleaned it and filled with another brand of Latex sealant and advised new tyres and showed and explained the tyre issue. On my bikes I use non latex Joe's Eco Sealant, never dries out, it just works and your tyres are clean inside. Another customer came by yesterday he'd been using a non latex but it would not seal a new tyre on the rim, he'd put extra sealant in and still no go. He stayed while I cleaned up what he'd had in and checked all the valve etc, he'd marked the rim area where the sealant wasn't working as it bubbled there. Lon story short, refitted tyre sans sealant..... and it was leaking where he said, a Dose of Joe's Eco...and sealed perfectly. 

The Main take really from the Tubeless debate is some sealants are much better than others, I have done "real world" testing on my own bikes and after various brands.... Joe's Eco is my go to...for me and when fresh build for it works and doesn't dry out. 

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