Slicy Products Smooth Tyre Inserts, Sealant and Valves – Reviewed

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David extends his tyre insert experience even further, with yet another test. This time, it’s banana yellow Smooth Tyre Inserts from Slicy Products.

Another foamy contender enters the ring. Hoop? Wheel.

Cyclorise do these in two widths, a small one for tyre 2.2in – 2.6in, and a wider one for 2.7in – 3.0in. The ones you see here are the narrower ones, which I ran with 2.4in tyres on a selection of 27.5in wheels.

These inserts are purely designed as impact protection, sitting quite high off the rim and only interacting with the bead seats during impacts.

Slicy Products Smooth Tyre Insert

Cyclorise sent these with valves and sealant, also by Slicy. So while I’m mostly reviewing the inserts, I’ll also tell you a bit about those.

Fitting the Smooth Tyre Inserts

These inserts come rolled up rather than folded, which makes them unfurl into a suitable round shape without any pre-stretching. The ends are joined by a hook and loop loop. I mean a loop of hook and loop, that’s not a bad Pingu impression. Look, “Velcro” is trademarked, okay?

Slicy Products Smooth Tyre Insert

Being of the type the sits up off the rim, these are extremely easy to get into your tyres. Nothing obstructs the tyre while you’re mounting, simply take one bead off, slip the insert in, and reseal. Of course, the design also means they don’t lock your tyre beads down either, so unlike some inserts these only offer pinch flat protection.

Slicy Slicy Products Smooth Tyre Insert
Slicy Products Smooth Tyre Insert

The insert arrives sized for a 29in rim, so I had to cut it down to size for the 27.5in wheels I ran it in. Easy job with a knife, especially given there are clearly marked notches to indicate lengths for 27.5in and 26in.

Slicy Valves And Sealant

The valves come in insert and non insert specific versions. The insert specific valves have the same base as the valves that ship with Cushcore and Rimpact, giving horizontal holes that can’t be blocked by an insert pushing down on it. Both types of valve have a cap with a valve tool machined into it, which I wish was more common. I’m not a big fan of integrated tools, but something this small makes total sense to me.

The sealant is made from recycled tyres, smells of bananas, claims to seal holes up to 6mm, and apparently will last six months before drying out. It also has no ammonia in, making it compatible with pretty much any tyre insert. It also mentions refill programme, which revolves around local bike shops rather than posting your package back to Cyclorise. At present the Slicy website only lists dealers in France, but hopefully it’ll come over here too.

Valve Performance

I didn’t get on with the valves, which is a shame because I love that they come with caps that have valve tools integrated into them. I found the bases are very soft though, and not so grippy, so had to tighten them to a golidlocks level of tightness. Too loose, they leak, too tight and they also leak air from the base, as I found on a resultingly suboptimal ride. The right amount of tightness did not stop them from spinning while connecting a pump.

Slicy Slicy Products Smooth Tyre Insert

I also found with a carbon rim slightly deeper than average, but not massively so, the valves were short and barely had enough thread showing to get the nut and cap on.

Sealant Performance

The Banana Sealant I also really wanted to like. Keep this well away from your kids. It looks and smells like banana milkshake, comes in packaging similar to some drinks brands, and the “DO NOT DRINK” warning label on the back blends in far too well.

In use, after a few rides I got a hole in my tyre, around 1mm long, that it just couldn’t seal. I’d put plenty of sealant in, but no luck. It is quite thick sealant, lining the tyre rather than sloshing around it, so after it failed to plug that hole, I added a little water. That did help get more sealant to the hole, but every time I pumped it up above 18PSI, it would extrude a little worm of whatever is meant to accrete in the sealant, then leak air again. Even after getting it to seal, leaving it for a day, then pumping it all the way up, it still couldn’t hold air at higher pressures. To make sure it wasn’t the tyre, I washed it out, cleaned the rim and added my usual (and ubiquitous) brand. The tyre went up to 30PSI and is still up, weeks later.

I do like the smell of this sealant, that’s there’s no ammonia, that parts of it are recycled, and that Slicy do refills. All admirable. If Slicy can improve the performance, I’d consider switching.

Insert Performance

I have reviewed so many inserts now, it’s hard to tell you anything unique about one. This is basically in the same ilk as Huck Norris, but slightly thicker, and I found it performed very similarly. This is hardly surprising, considering they’re very similar shapes and setups, but Slicy is a bit thicker and offers slightly more padding that the first iteration of Huck Norris did. Just like its forerunner, instead of hugging the rim, it floats around in-between tread and rim, for me just about filling the width of the 2.4in tyres I ran it with.

Slicy Slicy Products Smooth Tyre Insert

There are cutouts at the centre and sides to give plenty of sealant transit. While I did get the flat mentioned above, that might have been a sharp object rather than an impact, and I got no rim damage at all while running them.

On opening the tyre up after a couple of months, also like Huck Norris, it did have an assortment of slits and holes in it. What surprised me was that I hadn’t heard any telltale dinks at any time; whatever’s got through, the inserts seemed to do a fair amount of sound deadening. Unlike some inserts that can be audible in your tyre when riding, I never heard a peep from these.


Slicy Smooth is not as burly an insert as some, but nor is it as heavy. It’s a serviceable insert that’ll help keep you rolling. You can compare it to all the others I’ve reviewed in this spreadsheet. Despite loving the caps, I’d pass on the valves, and Slicy’s sealant could do with improvement. The inserts themselves work absolutely fine though.

Slicy Slicy Products Smooth Tyre Insert

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Review Info

Brand: Slicy Products
Product: Smooth Tyre Inserts, Sealant, Valves
Price: £39.99 per insert, £17.99 sealant, £19.99-£24.99 valves
Tested: by David Hayward for 3 months

David started mountain biking in the 90’s, by which he means “Ineptly jumping a Saracen Kili Racer off anything available in a nearby industrial estate”. After growing up and living in some extremely flat places, David moved to Yorkshire specifically for the mountain biking. This felt like a horrible mistake at first, because the hills are so steep, but you get used to them pretty quickly. Previously, David trifled with road and BMX, but mountain bikes always won. He’s most at peace battering down a rough trail, quietly fixing everything that does to a bike, or trying to figure out if that one click of compression damping has made things marginally better or worse. The inept jumping continues to this day.

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Comments (4)

    I too am finding valves are my faff issue with tubeless. I have taping down to an art form. I have good tyres I can trust. But valves remain a faff. As you suggest, too tight or too loose and they leak.

    Tyre valve test please!
    (and maybe tyre valve innovation as well please manufacturers.)

    @Matt, the very basic “conical rubber plug bonded on” type, like WTB sell but also like most cheap ebay ones, works well with almost any mtb rim imo, really unfussy about tape too, just whack ’em in. The ones with removable/changable bases or clever shapes all seem to be a solution for a problem modern mtb rims don’t have.

    I have used Stan’s valves with the cone shaped rubber base on wtb rims and have no issue with those.

    On my DT Swiss rims I’ve always run DT Swiss valves – never had them leak either.

    So in a survey of 2 types of valves I’ve never had them leaking or twisting easily.

    Yeah, I had a similar experience with the sealant – 2 punctures in 1 week not long after adding it, had managed over 3500 puncture free miles before…

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