Grip Geeking: Why do Some Brands Still Use Wire Beads in Their Gravity MTB Tires?

A few MTB brands make no bones about testing and prototyping, while others keep all the secrets until the product’s birthday bash. When Michelin unveiled their hilariously grippy DH22 tires a while back we had already seen the large yellow sidewall swatch rolling below EWS and World Cup DH bikes long before the tires were available to the public. The conspicuous canary-coated model first showed up in race photos in 2018 and was in the works for sometime before that.

Then, we received a set to test and found that they surprisingly use wire beads. While there are a few other wire bead race tires on the market, like the Maxxis Wetscream, it was surprising to find a new model using the seemingly dated tech. At 1500g each, the DH22 tires are some of the heaviest on the market, and fortunately, they offer industry-leading grip and casing-support to back up their heft.

We recently chatted with the brand’s business segment and race team manager, Vincent Ledieu, to find out how and why they selected wire beads for the new gravity race tires. First off we asked what the process is like for selecting gravity tire beads.

“When we launched the DH project, we had two options: working on the folding bead or working on wire bead.

“We decided to initiate work on both wire and folding beads but in terms of market perception, a wire bead was considered more reliable in terms of bead security on the rim. In fact, many riders are still thinking folding beads don’t hold up well enough in bike park conditions. For example, the ‘shralp’ trend we see today in bike parks confirms this need to get a maximum of ‘tightening’ to prevent air loss when cutting berms. We decided our folding bead technology was not quite yet ready, [so] we preferred to continue using wire beads.”

Is there anything different about how the rest of the carcass interacts with the wire bead as opposed to a folding tech? “For sure there are some minor differences in terms of ‘attachment’ of the structure, but not big enough ones to go into further details about.”

And, is there a quantitative difference between the forces required to burp a wire or folding bead? Ledieu answered this one as thoroughly as possible.

“It’s a complex equation that is not only based on the maximum force required to rip the wire or the folding bead. In fact, all tests we can do take into account the maximum grip, aging of the casing, mechanical fatigue of the tire, and the beads, etc. Unfortunately, we can’t give you any more detailed information because it’s confidential.”

So, since the pro athletes tested both wire and folding beads, what were their impressions? “Cam, Brook, Laurie, Vinny T, Carson, and Brage are all satisfied by the wire bead and don’t find bead ripping while riding.”

“We’ve just launched the Wild Enduro Racing Line, with a DH casing and MagiX DH compound, with a foldable bead. Our development team has been working on this topic since the beginning of our DH comeback project and a solution will come to the market. The folding technology will come on the market when all our DH and freeride riders validate this technology after several months of testing without issues. Technologies we develop for our clients are always validated by our fast guys.”

Sam Hill, 2019 EWS Canazei Italy

To talk about those fast folks a bit, we also asked Ledieu what he thinks of all the EWS riders choosing the DH22 as their grip for the season. “We’ve just launched the Wild Enduro Racing Line that was in long-term testing at a high level (racing support level). Now our enduro riders have access to numerous choices with the same level of reliability of casing and with the same level of grip provided by the MagiX DH compound.

“I would say it’s just a question of personal preference that is directly linked to riding style. As an example, Sam [Hill] prefers the DH22 because it’s a dynamic and very precise tire where Adrien Dailly prefers the Wild Enduro for its stability and predictability.”

With the new tires, are there elements that carry over from the DH models? “Shoulder blocks. We know that this shoulder block design is appreciated by most of the riders because it offers extra predictability and progressiveness while leaning.”

When we tested the DH22 tires it was clear that they perform differently at different ambient temperatures. On track temps, Ledieu said “The compound is constant down to around 5°C, and below 5°C the compound will be more rigid. It does not lose its grip level but gives a different handling feeling. It’s the same for most of your bicycle’s components like brakes, fork, and shock. Even spoke tension can change at lower temperatures.”

What about the added weight — is that just about rim-engagement and puncture protection? Ledieu replied that “the weight is not only a question of puncture protection. In fact, we’ve worked on many hidden aspects of performance.

“This casing gives you the possibility to choose a wide range of pressures for riding. For example, in very slippery conditions when you need a larger contact path, decrease your pressure, and you will not feel the casing burping — or less than what you did before.”

Michelin says the hefty 1500g weight is justified in part due to the fact that most won’t choose to run a tire insert with it because it is so durable. “Thanks to the bead and thanks to its stiffness, air loss through the beads are not so easy to create. […] Most of our clients are not using the full air pressure capability of the tire – and hearing some small pings on your rim does not mean you are going to break it.”

Having tested the tire without sealant, followed by zero flats, we’d have to agree. What about those inserts though? That’s something we have to ask every tire and rim manufacturer, as the technology continues to evolve. Ledieu had a lot of thoughts on the topic of adding foam between tires and rims.

“Tire inserts…that’s a long and tricky question. Michelin’s objective is to provide a tire that resists each kind of [impact]. Tire inserts decrease the air volume of the tire. As a comparison, everyone would like to ride a fork with a high-performance hydraulic system that prevents them from using volume spacers. Adding an insert to our tires means they can’t fully work and compress to give you the maximum grip. Entering a rock garden at full speed with inserts will make you lose the extra absorption characteristics given by the tire. However, if you hit a rock very hard and the rim is a bit worn, and your tire is new there is a chance you can damage it. It’s a question of choice.

“My main advice using tire inserts: Don’t downsize your tire casing. Inserts don’t prevent punctures, just pinches. Riding a Trail casing (or All Mountain casing for Europeans) will increase your risk of getting a flat if you ride it for Enduro usage due to a lack of puncture protection. With our Michelin DH Racing Line (DH22, DH34, DHMUD) don’t hesitate to ride them without tire inserts. You will notice that you don’t need them. Just ask our Michelin riders, as they don’t use them.”

2019 Italian National Downhill Champion, Eleonora Ferina attacking every last centimeter of the Les Gets hillside to earn 4th place on the day.

Okay, so we don’t need inserts with the heavier casings, but what else needs to change about tires, rims, and sealant to reduce punctures? In a perfect world, what would Michelin do?

“My point of view is to make life as simple as it can be for our customers. Each solution that is easy to use, to mount, and to maintain is the best. Inserts are pretty difficult to mount. Sealants don’t work all the time. I think the whole bicycle industry is working hard to prevent punctures and trying to make solutions as easy as possible to work with.

“Michelin’s target is to make its tires as strong as possible regarding the type of usage. Each time we solve some issues regarding a tire’s robustness, something new is appearing. It’s a continuous improvement cycle to be done by our development teams. We need to stay focused on our customers’ ease of use to make sure they are ready to go riding and live their passion.”

To find a balance between weight and riding performance, Michelin makes sure to test tires with pro and weekend riders alike.

“Our pro riders are here to test at the limits. But everyone who gets the chance to do a run with a pro rider will notice very quickly that he or she is losing contact with them in every corner or technical part of the track. Their speed is not the same! Our development team is always making long-term tests with some non-professional riders to be sure that we are not developing super specific tires for pro riders only. The subjective evaluation of the tire is always confirmed by pro riders and ‘normal’ riders. The range is validated for market usage only if all riders validate it!”

Finally, the DH22 tires were notably difficult to mount, so we asked Ledieu for a few pointers.

  1. Work with a clean rim and clean tire.
  2. Be sure to use clean rim tape. Each time the tape deforms too much into the rim’s hole it makes it increasingly difficult to seat the tire.
  3. Remove the core of the Presta valve to help increase the flow of air when pumping. It also helps to use a compressor if one is available.
  4. Start mounting each bead at the opposite side to the valve and ensure that the bead is kept in the channel until the last few centimeters.
  5. Finish mounting each bead at the valve.
  6. Before inflating, ensure that the bead is properly positioned in the wheel channel: you can roll the tire a bit on the ground while loading it with your hands.
  7. When you hear the tire seating (characteristic popping sound) stop the airflow.
  8. Very importantly, do not exceed the maximum recommended pressure.
  9. Using a syringe is always a cleaner way to add sealant through the Presta valve – after the tire is seated and the air has been let out of it.
  10. Finally, screw in the valve core and get out and ride.

That’s it for the DH22. Are there other tires you have questions about, or more general tire topics you would like us to explore? Please share them in the comments below.

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