Tire inserts for XC racing

So, went out on a new set of race wheels yesterday. 25mm internal, Continental Race King 29x2.2, with a Tubolight Evo SL. 30 minutes in put a huge gash in the sidewall of my rear tire, shooting sealant EVERYWHERE. Fortunately I’d just come out on a road 1/4 mile from the house and was able to limp home for my other set of wheels and finish my ride.

Just bad luck? Inappropriate for my local trails? Pressure too high? I did notice that I’m right at the bottom of the tire size range, and internal rim width range, so the insert is “snug” against the sidewall.

My plan for these is a Leadville wheelset (and similar) so want to make sure I feel confident in the setup…

Also, the valves I have in these wheels are Stans Tubeless, and don’t work worth a damn. They clog from the sealant and probably the insert, so have new ones coming from amazon to try out.

I responded on the Leadville thread, but take a look at the newest gen Muc-Off valves or the Santa Cruz Fillmore’s as alternative valves.


I’m considering hopping on the insert wagon for my race wheelset, but it’s hard to justify the cost of this glorified foam when I very, very rarely puncture. I realize the inserts are more than just puncture protection, but I seem to read pretty mixed reviews on whether or not they’re really worth it. Running lower pressures is very appealing to me, so maybe I’ll give it a go. Thought I’d go with just a rear insert to save money, but then that defeats the purpose of running lower PSI in the front tire too. It’s hard for me to want to spend $120+ on inserts when it may or may not make any difference to me.

I have found the new Muc-Off V2 tubeless values are excellent even with inserts. I have them on my MTB and gravel wheelsets and have had no clogging issues. Older values were useless with inserts, you couldn’t even get air in because the insert blocked the air inlet.


Looking for an alternative to the tubolight sl. Ran them in my xc bike last year, loved the performance but they seem to absorb a ton of sealant. Is there anything with comparable weight and performance that doesn’t absorb sealant as much? If not, how often should I be topping up the tubolights? I can’t help but feel that if they’re absorbing all this sealant the weight will end gradually getting quite significant.

After asking the exact same question in another forum the answer there was Vittoria Air Liner.

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One season on Tubolight Evo SLs (one flat in the season ridden to the pits and then plugged and gased).

We have a team deal with vittoria so will try their version this year.

Interestingly if anyone reads pinkbike as well you’ll find a big article where all of the tyre and rim manufacturers basically say “Inserts are generally bad and you should just use a more robust tyre and/or rim and/or better designed bead” (and obviously the insert people say “inserts are great”).

I honestly actually think that XCO and Gravel and Amateur Road (where you don’t have a team car to give you a wheel) are the only good use cases - where you might need to run flat before you can fix. Enduro? Better tyre, more air.

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I used a rear cushcore on my old enduro bike with weareone wheels. They say not to use inserts, but I really liked the feel of them with EXO casings. This exact setup (I swear everyone in the sea to sky has weareone wheels) was very popular for a while, but now everyone seems to be switching to exo+ or dh casings and no inserts for enduro.

I saw this, but I think that for XC, they generally are worth it, particularly marathon. When I flat, it’s usually a pinch on a sharp edge, and as someone who uses xc tires, the rolling resistance allowed by the the fastest casing that won’t cut is worth more than the extra resistance to pinching of heavier casings. When I’ve killed rims, it’s always been with a point load too, so spreading the load with an insert as opposed to not seems like a good idea to me. I’m not running weight weenie rims though, so that could be a factor


Thoughts and feedback on this new tire liner? Anyone testing these out since I imagine these are not available to the public yet?

Some general thoughts:

I wonder how much sealant it soaks up?

At 200 grams (100-ish / tire) before the sealant absorption. Is it worth it for the trails you ride to add the weight? People pay a lot of money to lose half a pound on an XC bike.

I have both Used Vittoria Airliner and Tubolight Evo SL (dried out) that I can weigh at home and take pictures of to show how they wear. Neither of them fell apart after a decent amount of use.

Currently my pick would be Vittoria. They do initially feel less porous, no center channel for the Sealant to dump into (it’s forced in between tire and insert), and a little bit lighter. But, they did feel a little more porous used than they were initially when new. But, I don’t think it’s a huge difference between the two.

I will say it is harder for me to get a tire off with them on. So, make sure you practice and don’t do it for the first time during an event. But for a Marathon Event I am 100% a fan of running them. I’m racing a 100K and two 100 Milers (Lutsen and Leadville) this year, and I will be running them.

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I haven’t caved in yet but was thinking maybe this year especially after reading that article, I might try it for some marathon events. I’m probably leaning towards the Vittoria’s so this is good info unless these new Turbolights are the bomb and available.

For the Vittoria’s, what sealant were you using once you noticed the more porous effect?

Just to be clear - these have been used starting last season, and were recently taken out, dried off, and cleaned off. So, they’re not going to look perfect and the smooth surface roughens up a litle. I’ll take more pictures and weigh in the next day or so. I had the advantage of having Tubolight’s in one set of wheels, and the Vittoria’s in another with similar use so it’ll be a very good comparison.

With that said, I’ve exclusively used orange seal.

I do think an interesting test would be to take them out of a tire, let them drip dry for a couple minutes, and weigh them on the spot to see how much sealant is absorbed into the insert when it’s wet and sealed inside the tire. I will say though that I always get plenty of sealant wanting to squirt out the valve so it’s not something I’ve ever been concerned about, and I start fresh before big events anyways.

You’d absolutely be at risk of just weighing whatever sealant is attached to the surface area of the foam which would not be reproducible.

I’ve sort of never understood this accusation or why it seems to perpetuate. Closed cell foams and silicones don’t absorb water. They are no more physically able to absorb water than a lump of plastic or a rock or your tyre. What happens is that more complex shapes find sealant clings to them by surface tension and as it dries out, gets even more stuck to it. Or what happens is that the insert continually squishes sealant between it and the tyre, slowly reducing the spinbarkeit.

Insert is Absorbing Sealant | RIMPACT (rimpactmtb.com)


etc etc

Some inserts are pourous and “drink” sealant. True this is different in closed cell material.

That said, do you know if this holds true if you cut the insert?

My tubolights get cut real easy, and I don’t buy the airflow claims. I hope that these are substantially more durable. My normal small airliners protect well, and they are 4-5 years old and still better, and are only 90g each end

According to the Bikerumor article:

”Tubolight Diamana liners are made of high-density closed-cell EVA foam – guaranteed 100% absorption-free to work with any sealant.”

Do you know if this is true even if they are cut?

I’m no materials science expert but I’m pretty sure when closed cell foam is cut it’s only the cut cells that can fill with fluid. Same thing as a swimming pool noodle and those still float just fine even when damaged (plus they have ‘cut’ ends from new).

In other words, I’m pretty sure it’s more like those strips of bags of air you get as packing material than like a porous material sheathed in a waterproof casing.