Tubeless tyre inserts – lengths of foam fitted inside the tyre – are becoming increasingly common for both mountain bike and gravel bike setups, but could they be set to appear on road bike setups too? We've already heard about them being used in the pro peloton and here’s how we think roadies might use this tech.
If you’ve no idea what we’re talking about, a tubeless insert is a length of foam that wraps around the wheel, sitting inside the tyre. Most will not fill the whole tyre and many claim to avoid soaking up tyre sealant. The two most common reasons cited for using tubeless inserts is rim protection when a tyre 'bottoms out' and improved bead retention to help keep the tyre on the rim at low pressures.
Mountain bike inserts have come down in weight recently, with a good insert adding a little under 100g to each wheel. With a narrower profile for use with road tyres, this weight would come down even more, although there will still be a weight penalty associated with tubeless inserts.
In the world of mountain biking and gravel, foam inserts are generally a protective measure to guard against rim impacts when using super-low pressures for added traction. Some are also claimed to aid tubeless bead retention, again a benefit when running lower tyre pressures as ‘burping’ air is often an issue for mountain bike and cyclocross tubeless setups.
You can always count on pro team mechanics to come up with innovative solutions to bike problems and when The Cycling Podcast featured EF Education First rider Mitch Docker chatting to team mechanic Jac-Johann Steyn, it transpired that the EF mechanics had come up with a few nifty hacks when running tubeless tyres in races.
The EF solution, as we will name it, is born out of a problem that is quite specific to pro racers. Tubular tyres are generally considered to be quite safe as the rider can continue to ride on a deflated tyre should a puncture befall them in the middle of the peloton. This is because the tyre is glued to the rim and requires a significant amount of force to remove when installed correctly.
A tube-type clincher or tubeless tyre is not glued to the rim and relies mostly on air pressure to keep the tyre safely on the rim. When a puncture reduces air pressure in the tyre, safety can be badly compromised and if you keep riding on a deflated tubeless tyre, there’s a risk of the bead unseating.
So Steyn, when explaining some secret tech that EF has been using, appears to show how the mechanics have navigated past this problem. Steyn starts talking about tyres at 41 minutes in, but the whole podcast is well worth a listen.
“We have, I call it a sponge inside. I can’t go into detail about it because it’s always a secret to other teams, but that’s basically our safety and you can still ride it.
“It feels like you’ve almost got 2.0 Bar (20 psi) in your tyres so you can still ride with it wherever you need to go.”
Docker then says that he punctured the day before when using the system and was able to continue riding, only noticing the tyre was punctured when he went through a couple of corners.
Steyn says, “That’s basically the purpose. It’s to help you get to some point where you can get a new wheel. In the future, I think that’s what we’re going to go. And it’s also a safety thing. Like for what we’re using, if you don’t use that foam insert and the tyre’s deflated, and it comes off, you may crash.”
Vittoria is the tyre sponsor for EF Education First and so, with the gravel version of Vittoria’s Air-Liner already on the market, it isn’t a huge stretch to imagine that a narrower version, probably for use with 25-28mm tyres is at the prototype stage of production at the very least.
When we consider that The Cycling Podcast episode where Steyn reveals the trick was recorded during the Classics races in August, it could be that we see a finished product in early 2021.
How relevant is this to non-professional riders? Well, if you were to have a sudden loss of pressure when travelling at speed, then having something to stop the tyre bead from unseating is surely a good thing. Non-pros might also be attracted to a tyre insert as a 'get-me-home' option.
Steyn talks about the lack of sealant being used when combined with the tubeless liner. This could be an interesting approach for riders looking for the fastest setup.
“We basically brush the tyres with sealant before so it dries out. It’s just like the small bubbles of air escaping, we just seal that off. That’s something we’re experimenting with now, because tubeless is obviously a new thing on the road for us, just to make sure. Is it working? Is it not working? Do we need to put sealant? Do we not need to put sealant?”
The ability to simply ‘brush’ sealant onto the inside of a tyre will depend on the sealant that you’re using and the tyre that you’re brushing it onto.
If Steyn is brushing the sealant onto a Vittoria Corsa tubeless tyre as we’d expect then this is unlikely to be for puncture sealing purposes and more to do with making a slightly porous casing properly airtight.
This could be giving a pro a fast setup with a bit of security in the event of a puncture. Unlike the rest of us, they can simply roll along at the back of the peloton and await a new wheel from the team car.
You haven’t got many insert options for standard road tyres, at least not for those that are under 28mm wide. Vittoria has the Air-Liner Gravel that we think EF might have been using in a slimmer profile. This currently comes in only a gravel version and Vittoria claims it will fit tyres from 31mm to 40mm. You’ll need a relatively wide internal rim width, though; Vittoria says that this works with inner rim widths of up to 25mm. We’d be surprised if it fits a rim that is less than 19mm wide internally.
Tubolite’s Puncture Prevention Insert is another option, and at a claimed 22g it is also one of the lighter solutions on the market. This claims to work with rim widths of between 15mm and 22.4mm and is compatible with tyre widths of 28mm and above.
The life of a pro team mechanic might be about to change from brushing tubular glue onto rims to brushing tubeless sealant onto tyres, but what if you want to get the puncture-sealing benefits of tubeless while using a tyre insert? How much sealant do you need?
The world of off-road riding has a few theories on this one. Some brands, such as Cush Core, claim that no additional sealant is needed when installing tyres with their insert.
Other brands, such as Rimpact say that you’ll need to add additional sealant. Rimpact says to add 25% more and off.road.cc's Rachael Gurney says that when she fitted a Tannus insert, it needed a decent amount more while also noticing that it dried out quicker when using her normal sealant.
Unfortunately, it seems that a fair amount of trial and error is going to be required for any early adopters of tubeless inserts on road setups.
How much these pieces of foam will affect rolling resistance and the tubeless experience is unclear, but we’ll be the first to put our hands up to give it a go.
Son of a Marathon runner, Nephew of a National 24hr Champion, the racing genetics have completely passed him by. After joining the road.cc staff in 2016 as a reviewer, Liam quickly started writing feature articles and news pieces. After a little time living in Canada, where he spent most of his time eating poutine, Liam returned with the launch of DealClincher, taking over the Editor role at the start of 2018. At the weekend, Liam can be found racing on the road both in the UK and abroad, though he prefers the muddy fields of cyclocross. To date, his biggest race win is to the front of the cafe queue.