Tire inserts for XC racing

I would, but shipping from Canada to Australia = $$$

24 grams for CX wheel - M-D Building Products Gray Foam Caulk Backer Rod - 1 in. (ACE Hardware).

Well … first test ride seemed to go pretty well.

But maybe I had the pressure a little low at a little under 20psi - or maybe the tyre is a bit old and maybe it didn’t seat quite right when I re-fitted it.

Bottomed out the rim at one point I would say due to it losing some air somewhere before that. I would have expected the foam to take the hit but the rim made a good clang and one of my spokes ended up loose.

I’m tempted to put this down as a failed experiment when I swap out for the new tyre.

CX 33 tire - Working really well BTW, taken down PSI 1-2 and tire feels well supported. When in use it is amazing to compare riding a front without the insert and a back with, over a square edge obstacle (raised concrete path), the front is an uncomfortable hit whereas the back hit is absorbed.

Ran file tread using insert in a race this weekend, everything really good, although I am 100% sure it saved my rim when I failed to bunny hop a log at speed.

“Looking forwards” (?) to running this in mud where I will probably run front and back at the same PSI.

Has anyone tried the tubolight mousse MTB insert? Its on sale right now if you want to check it out yourself.

^ Just bought one for the rear - will update on how it is.

Very interested to see what you think. I hadn’t seen them, I’m curious how they can avoid soaking up the sealant being so low density. Weight, price and fitment look great though.


planning to do a few gravel races and XC marathons next year and thinking about whether to get tire inserts too.
My bro science is telling me that lower tire pressure is bad for rolling resistance, but it seems like tire inserts are quite common for XC racing now. So either my bro science is wrong or the benefits outweigh that. Very curious which one it is :slight_smile:

For the gravel events, I’ll repurpose my roadbike and will be running the Hunt 4 Season wheelset ( https://us.huntbikewheels.com/products/4season-gravel-disc-road-cx-wheelset-1589g-24deep-24wide ) with 32mm tubeless gravel tires. Thinking it might be smart to run inserts there as well, so I can run lower pressure for comfort/grip? What do you think?

It’s a little bit of both. On rough terrain low pressure rolls faster, because the tire deforms through a bump rather than having to roll up and over. In addition low pressure provides more traction, allowing you to climb steep technical trails faster and corner faster. At marathon distances the comfort factor comes into play as well.

On smooth gravel and pavement the ideal pressure would be higher, of course. Still probably not as high as many people think though.


The main goal of inserts is to protect the rim while running lower pressures.

I don’t think inserts will be much benefit for gravel - unless you are riding some really gnarly gravel.

For XC marathon, it depends on the course. Probably more needed for a course like Grand Junction off-road vs Leadville.

Silca Blog

Best article I’ve read explaining why the pure rolling resistance drum tests tell you higher pressure is best, even though higher pressure feels bad on rough surfaces.


Heres my review for the Tubolighto Mousse (Pretty sure @Jonathan has these in his new epic). I ride a Trek Procal with older enve m50s.

MAIN BENEFIT: You can run 1-2psi EASILY, and can run even less on some courses
MAIN BENEFIT: Rim strikes are very uncommon
SMALL BENEFIT: More support in the corners

The installation was pretty easy. Watch cushcore installation tip videos. I did not notice the weight. I did not feel like it held my line any better. I completed technical climbs I have never done before. The 1-2psi less is very noticeable and gives so much better grip and rolling resistance. It is exactly like tokens in suspension, more supple off the top and still does not bottom out all the time.


I have been using the Tubolights.

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Did you get them local or via the italian link above?

I got them direct from https://r2-bike.com/

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Awesome, thanks for that - will have a look

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Bike and tire punishment yesterday in the desert. And this was on a smooth (although flat) landing with no rocks.

No flats, but seeing what tires go through makes me wonder If I should run inserts.


Anyone aware of ultra light inserts in the US that doesn’t require $50+ shipping?

Love my XC Cush but theys heavy.

Long time hold out here - I’ll never go back. Nice missing your marks without the fear of killing rims.

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I buy most stuff from ExcelSports (Colorado) and this Oregon company: Vittoria Air-Liner Gravel Tubeless Tire Insert [1AA00019] at BikeTiresDirect

product info: https://www.vittoria.com/us/en/bike-accessories/tire-inserts/air-liner-gravel