Like this site? Help us to make it better.


CST Tubeless Tyre Sealant



Works on the majority of holes, and though it doesn't quite hit its claims it’s still impressive
Very effective on smaller holes and cuts
No signs of it starting to dry out
Doesn't fully seal large cuts, as claimed

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.

What the scores mean

Good scores are more common than bad, because fortunately good products are more common than bad.

  • Exceptional
  • Excellent
  • Very Good
  • Good
  • Quite good
  • Average
  • Not so good
  • Poor
  • Bad
  • Appalling

I've been using CST Tubeless Tyre Sealant for an extended test period, and it has been working well, plugging smaller holes quickly and showing no signs of drying out even with the very hot weather we've had. And though it hasn't lived up to the big 7mm holes claim, it does come very close.

Most tubeless sealants are claimed as being able to fix holes from around 3mm up to 5mm, but CST reckons its offering can seal up to 7mm diameter holes.

To test this, I pierced one of my gravel tyres with the point of a flat wood 32mm drill bit, leaving a hole of around 2mm in width and 6.5mm in length to see just how good the CST sealant was at dealing with what would be quite a severe gash out on the trails. It didn't fully seal it, though it did give it a very good go.

> Buy this online here

The 40mm tyre was pumped to 40psi before piercing, and the sealant started to block the hole quickly, with very little in the way of pressure loss. Although it didn't seal the hole completely, it did slow down air loss, allowing me to keep riding for about 20 minutes before the tyre was flat. This might give you enough time to get home, or at least get somewhere flat or dry away from the road or track to fix it.

On smaller, more typical holes you'd get from glass, thorns, sharp stones and the like, I found the CST sealant to be very good. Installation is simple, too, thanks to the nozzle easily fitting inside the valve core, so you don't end up with any mess.

Using an old tubeless road tyre that had previously been fitted with an inner tube, I was amazed at how many small nicks and cuts were on it. The sealant quickly showed itself and sealed all of these small holes – and they have remained sealed even after a few hundred miles.

It copes well with higher road pressures without blowing out, too.

We've had some very hot conditions during the test period, and after a couple of months of use, removing the tyre showed the sealant to still be very much a liquid, with no sign of any of it 'balling' in certain areas of the tyre.

CST recommends topping it up every six months, or three months if you live in hot climes.

> 9 things they don’t tell you about tubeless tyres

At £10 for 250ml (£4 per 100ml) it's not priced too badly; it's a cheaper option than Muc-Off's No Puncture Hassle sealant at £8.99 for a 140ml sachet (£6.42 per 100ml).

The Hutchinson Protectair Max sealant is £6.95 for 120ml (£5.79 per 100ml), while Juice Lubes offers its tubeless sealant at £5.99 for 140ml (£4.27 per 100ml).

When it comes to quantities used, that ranges from 30-50ml for up to a 32mm road tyre, 50-80ml for a 700C gravel tyre, up to 140ml for a downhill mountain bike tyre, so for most of us roadies you're going to be looking at around five tyres' worth of sealant.


Overall, although I couldn't quite get the largest hole to seal, the CST made a pretty good effort, and for the more typically sized punctures you are likely to pick up I'd say it's a sealant you can rely on.


Works on the majority of holes, and though it doesn't quite hit its claims it’s still impressive test report

Make and model: CST Tubeless Tyre Sealant

Size tested: 250ml

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?

CST says, "CST tubeless tyre sealant has been engineered to seal holes of up to a whopping 7mm in diameter, ensuring riders can continue to ride on some of the most hazardous surfaces with full confidence that they can still cycle home. Formulated to spread evenly throughout the inside of the whole tyre, the sealant's anti-ball formula ensures even, perfect coverage for continued smooth riding, minimal rolling resistance, and all-round puncture protection.

In addition, CST's Tyre Sealant is made in the UK, supporting the UK economy and reducing CST's carbon footprint."

It's a good sealant that'll work on various tyre types and pressures.

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

CST lists:

Anti-ball formula

300ml bottle

Clings to the whole inner tyre

700c 23-32mm - 30-50ml

700c 32-50mm - 50-80ml

26" up to 2.5" - 80ml

27.5" up to 2.5" - 100ml

29" up to 2.5" - 120ml

Downhill up to 2.5" - 140ml

Rate the product for quality of construction:
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 didn't match the claims on the bottle, but does a good job on the majority of holes.

Tell us what you particularly liked about the product

It's well priced and worked well on typical sized punctures.

Tell us what you particularly disliked about the product

It didn't work on the largest hole I tried.

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

It's more cost effective than many when it comes to buying it in small packages like this, some by a big margin, as you can see from the review.

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

A decent sealant for the majority of punctures and sealing jobs, though it didn't hit its 7mm hole claim in testing.

Overall rating: 7/10

About the tester

Age: 42  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!

Add new comment


ktache | 2 years ago

It appears to be hedge trimming season, pulled out a nasty thorn last week from my thorn magnet Maxxis chronicals and one which remained attached to a stick.

If there is one reason for going tubeless for me is hedge trimming (slashing...).

Latest Comments