2020 Tour de France tech: Inside EF’s tubeless tire foam party

At no other time in modern road racing history has there been such a multi-pronged assault on the once-untouchable tubular tire. However, with every team perpetually in the search for free watts — and a growing body of evidence that ultra-fast-rolling tubeless…

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At no other time in modern road racing history has there been such a multi-pronged assault on the once-untouchable tubular tire. However, with every team perpetually in the search for free watts — and a growing body of evidence that ultra-fast-rolling tubeless and even tube-type clinchers now offer exactly that — there’s a distinct absence of telltale tubular glue scent in the air at certain team pit areas.

Speed isn’t everything in this arena, though, so there’s also been a surprising amount of experimentation as teams and riders figure out how to make various clinchers work best for their unique needs. The EF Education First team has perhaps the most intriguing setup to date — and it involves a “sponge”.

Safety first

One of the biggest reasons tubulars have persisted as long as they have is because they stay on the rim when flat, which is particularly helpful when you’ve got a puncture and can’t grab a spare wheel or bike right away. Riding on a deflated tubular obviously isn’t ideal, but the fact that it’s securely glued on to the rim is a big plus for pro racers, as is the fact that the tire — even when flat — still covers the edges of the rim so the rider is less likely to be rolling on bare carbon fiber or metal.

Tubulars are still generally lighter than clinchers, but it’s also a big draw for pro racers that they’re securely glued on to the rim so they stay on whether or not there’s air pressure inside. Photo: James Huang.

Clinchers, on the other hand, aren’t nearly as accommodating when ridden flat. Air pressure is what holds the tire on the rim, after all, and even if the tire manages to stay seated, the casing still tends to fold over, exposing the bare rim to the ground.

The sealants typically used in tubeless setups can present problems, too. Most amateur riders have just one, or at least some small number, of bikes at their disposal that are ridden regularly. In contrast, pro teams have hundreds of bikes and wheels on hand, many of which are lying fallow in a service course or truck, and with tires already installed. With a tubular tire, you can reliably grab a wheel that’s been hanging from the rafters for a few months and be good to go. But with tubeless, the liquid latex sealant inside the casing will likely have dried to some extent, which not only diminishes the self-healing capability in the event of a minor puncture, but also introduces a potentially dramatic level of imbalance that is hardly desirable when rocketing down an alpine col at 100 km/h.

In other words, tubeless setups are yet another example of how professional racers’ needs are not the same as yours and mine.

Tire sealant has an annoying habit of drying up over time. It’s a relatively minor inconvenience for amateur riders, but it can be a big problem for pro teams. Photo: James Huang.

A bit of foam apparently goes a long way

Top-level teams are notoriously secretive when it comes to technical innovations they believe will give them even the slightest edge, but EF team rider Mitch Docker may have inadvertently spilled the beans during a recent episode of The Cycling Podcast, in which he interviews one of his team mechanics, Jac-Johann Steyn.

Steyn describes how EF is using its Vittoria tubeless setups, and it’s anything but conventional. EF basically isn’t really using sealant at all — at least not in the way it’s normally used.

Tubeless road tires are usually set up with a small amount of liquid latex sealant inside to ensure everything stays airtight, and to help seal small punctures. EF is apparently doing things differently, though. Photo: James Huang.

“We prepare the tires a little bit different to what they normally recommend to us,” Steyn said. “We basically brush the tires 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?’ And also, if you put sealant, like now, we’ve been off for three months, it dries out so we have to change the tires even though the tires are still brand new.”

That approach takes care of one problem, but there’s still the issue of security if and when the tire does go flat in the middle of the race and the rider has no choice but to carry on. And it’s here where EF’s approach is particularly intriguing.

“We have, I call it like a sponge inside,” he continued. “I can’t go into detail about it because it’s always a secret to other teams, but yeah, that’s basically our safety and you can still ride it. You still have that little bit — it almost feels like you’ve got like two bars in your tires so you can still ride with it wherever you need to go.

“That’s basically the purpose of that. 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 tire’s deflated, and it comes off, you may crash.”

Docker himself confirmed the effectiveness of the team’s approach when he described his experience of getting a flat on the road.

“It’s quite good,” he said. “I punctured yesterday and it was nice. I didn’t know I had a puncture until I went around two corners and you sort of felt the back slip out. You could have ridden it quite a long way.”

While Steyn indeed didn’t go into great detail on what exactly EF is putting inside its tires, it sounds similar in concept to the foam inserts that have already been popular for years in the mountain bike world — items like CushCore, Huck Norris, the Vittoria Air-Liner, and Effetto Mariposa’s Tyre Invader.

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CushCore is one popular brand of foam tire insert in the mountain bike world, and the company recently added a smaller size for gravel and cyclocross applications, but there’s currently no road option – yet. Photo: James Huang.
Effetto Mariposa’s TyreInvader foam tire liner is basically just a flat strip of higher-density foam that protects the rim from damage, prevents pinch flats, and makes the tire more rideable when flat. This sort of setup seems more likely to be readily adapted to the road (and it’s lighter than bigger foam inserts, too). Photo: James Huang.
Several companies – the Vittoria Air-Liner is shown here – offer foam liners that fill more of the tire casing volume than flatter and more minimal-looking designs. Such a setup would almost certainly be overkill in a road setting, though. Photo: James Huang.


For most of these products, the primary benefit is that it allows riders to run lower air pressure — thus improving tire traction — without fear of pinch-flatting or damaging a rim. Alternatively, liners that fill more of the tire cavity, such as CushCore and Air-Liner, also provide additional casing support so that the tire feels more stable that you might otherwise expect at those lower pressures.

Shrouded in mystery

What exactly the team is using isn’t entirely clear (and team representatives declined to comment when I asked for additional information). The more voluminous types of foam tire liners would be overkill in a road situation given the higher inflation pressures, so the more basic ones — which are essentially just higher-density strips of closed-cell foam spanning the width of the tire casing — seem more probable given their lower weights and very minimal effect on rolling resistance.

However, something like a purpose-built and dramatically downsized CushCore insert that helps lock the tire beads on to the rim and cushions the rim from direct contact with the asphalt isn’t outside the realm of possibility, either. Regardless, given that none of the major tire insert company currently offers something sufficiently narrow for road use indicates that EF is either using something custom-built, or is serving as a test bed for a pending release of a production product.

EF is one team that has been quite bullish on tubeless road tires. But so far, all we’ve found on team bikes at the Tour de France are tubulars. Photo: Phil Golston.

Either way, it’s worth pointing out that EF doesn’t appear to have actually made use of this “sponge” in this year’s Tour — from what I can tell, the team has reverted back to traditional tubulars for these earlier stages. However, it’ll be interesting to see if this novel tubeless setup makes an appearance later, particularly on stage 18, which includes a bit of gravel, or the individual time trial two days later.

Whatever EF is hiding inside its tubeless tires, this certainly seems like an escalation in terms of teams’ quests for a performance edge, and one that isn’t likely to slow down any time soon.

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