In this article, we’ll be discussing a Tire for Bicycle Tubeless Wheel by Cheng Shin Rubber Co. (Maxxis), US patent 10,906,360. The publication date is Feb. 2nd, 2021 and the filing date is May 8th, 2017. This is a granted patent, which means the USPTO considers this novel.
As you’ve probably noticed, Maxxis is the DBA (doing business as) name for Cheng Shin, a massive Taiwanese tire manufacturer. I’ll refer to them as ‘Maxxis’ throughout this article.
I have not been able to find this design anywhere on the internet, but please feel free to prove me wrong. Maxxis makes tires for a shit load of applications, so I could have missed it.
This patent has images of a typical road tire, but like many other patents, Maxxis don’t say what the explicit application is for, allowing them to use this technology on any tubeless system.
Brief Summary (tl;dr)
Maxxis are introducing a tire for a flangeless rim design. They say this has multiple advantages relating to rim manufacturing, tire installation, aero, and tire damage. The bead area of the tire has a very specific shape with very specific dimensions to achieve the desired performance characteristics.
A tire bead is the area of a tire that sits in a groove in the rim of the wheel. The bead provides support to the tire and prevents air from escaping, and can allow for lower pressures, resulting in more grip.
In general, there are two types of tires: tubular and clincher. Tubular tires are just round tires that sit on a rim. There is no bead. A clincher does exactly what the name implies; it clinches to the rim via the bead—credit to Bike Exchange on this photo below.
Typically, a bead can be foldable or wired. A folding bead is lighter and easier to install. A wire bead provides significant support and sucks to install. As a result, a wire bead can run lower pressures without falling off the rim. Wire beads appear to be falling from grace as folding bead technology improves. The image below shows the composition of a Maxxis tire.
This patent reminds me of the WTB TCS system (below) introduced a few years ago (though there are other systems in the history of bike tires). WTB developed an entire wheel/tape/sealant/tire system that probably works very well. I’ve never used it, but there appears to be a lot of thought put into that system, and I can’t imagine it working poorly. On the flip side, it requires an entire system to function (at least a tire and wheel). The bike industry typically aren’t fans of proprietary systems. Or it’s just the loudest that aren’t fans. The internet… amirite?
I love Maxxis tires. Like many of you, I use them exclusively. The DHF’s front/rear are amazing. Better yet, the Assagai is incredible for the Colorado marbles. I’ve gotten into turns that I was convinced I was about to break grip and eat shit, and these things just hold.
They are trying to remove the flange located on the inside of the typical rim structure. The flange keeps the tire in place, but according to Maxxis, there are many drawbacks to the flange. They explain them in the ‘why’ section.
As I said before, the system Maxxis are introducing reminds me of the WTB TCS system. There is, what Maxxis is calling, an ‘installation unit’ that is integrally formed on each lip, and each lip fits into a specific rim perfectly. They also have a specific rim shape drawn in this patent application, meaning this may require a rim to suit this tire design.
It appears as though Maxxis’s intended novelty is this entire system, not one small piece. The ‘installation unit’ is located on each lip of the tire and has a flat side and underside that is adjacent to a rim. Each of the sides slide in a concave portion of the rim. The angles and lengths noted by the Greek letters in Fig. 3 below are very specific to this design, and they’re trying to protect them.
Here’s exactly what they say these dimensions should be:
…an angle α of 0 to 45 degrees is defined between the underside 22 and a horizontal plane. The underside 22 of each lip 13 has a width β of 2 to 8 mm. The outside 23 is formed with the outer surface of the sidewall 12, and a thickness difference δ of 0 to 1 mm is formed between the outside 23 and the outer surface of the sidewall 12. The outside 23 is thicker than the sidewall 12. The outside 23 has a height ϒ of 1 to 6 mm. A rounded corner ω of 0.3 to 1.5 mm is defined at the connection portion between the underside 22 and the outside 23. An obtuse angle ρ of 135 to 180 degrees is defined between the outside 23 and the outer face 24. A vertical height μ of 6 to 9 mm is formed between the first edge 27 and the first engaging ridge 25.
It appears as though Maxxis are doing this for a few reasons. First, they want to reduce the costs of rim manufacturing by removing the flanges.
…the convention rim includes a flange extending from each of the sidewalls of the rim so as to be engaged with the lips of the tire. Nevertheless, the rim with the flanges requires higher manufacturing cost, especially when the rim is made of carbon-fibers.
Additionally, Maxxis say these flanges cause stresses:
…the flanges cause 40 concentration of stress when braking.
They state the deformation of the tire due to the flanges may cause wind resistance. This is definitely a road cycling use case.
…in order to be engaged with the flanges, the sidewalls of the tire have to be deformed severely and the deformation causes wind resistance when in use.
In the end, Maxxis appear to be making a new tire to work with a flangeless rim.
The tire of the present invention is suitable for being installed to the rim that does not have any flange extending from the sidewalls thereof.
First, we’ll define the ‘installation unit 20’ of this system. Fig. 2 below shows an inside 21, underside 22, and outside 23, which comprise the lip 13. It also includes the outer face 24 and an engaging ridge 25.
This installation unit fits perfectly inside a matching rim. Figures 5-7 show the installation process of this rim. Fig. 5 is being described as the initial part of the installation. With the removal of the flanges from the rim, the tire should be fairly easy to install with some tire levers.
Figure 6 shows an intermediate step of inflation. Notice how the very specific shape of the installation unit and the rim provides an air-tight seal to the rim.
Figure 7 shows an installed tire on the rim. Maxxis explains this more concisely than I can:
…when the tire is inflated completely, the tire is secured to the inside of the rim. The toes 26 contact the engaging portions 52. The first engaging ridges 25 are engaged with the top faces 51 of the sidewalls 53 of the rim 50. The underside 22 and the outside 23 of each lip 13 of the tire 10 are fully matched with the sidewall 53 and the seat 54. Because the outsides 23 each are a flat side so that when the tire 10 is inflated, the outsides 23 are matched with the sidewalls 53 at a large contact area. The undersides 22 of each lip 13 is a flat face so that the undersides 22 are matched with the seats 54 when the tire 10 is inflated.
Maxxis are just saying that everything is sealed to everything else. That’s pretty easy to do when you design the tire and rim together.
They end with some final thoughts on the advantages of this system:
The advantages of the present invention… are that the sidewalls 53 of the rim 50 each have flat inside and outside, and there is no flange extending from the sidewalls 53 of the rim 50, the structure of the rim 50 becomes simple and easily to be manufactured.
Additionally, Maxxis explain the advantages of the ridges and the toes:
When the tire 10 is inflated, the first engaging ridges 25 are engaged with the top faces 51 of the sidewalls 53 of the 55 rim 50. The toes 26 of the tire 10 are engaged with the engaging portions 52 of the rim 50, so that the tire 10 is securely installed to the rim 50.
They also state the air-tight features:
When the tire 10 is installed to the rim 50 and inflated completely, the underside 22 and the outside 23 of each lip 13 of the tire 10 are fully matched with the sidewall 53 and the seat 54. The contact area between the underside 22 and the outside 23 of the tire 10 and the sidewall 53 and the seat 54 of the rim is sufficient so as to have better air-tight features.
Maxxis state aerodynamic advantages for this system:
The outer face 24 of each lip 13 is a flat face and which is properly bent when the tire 10 is inflated because the rim 50 does not have any flange extending therefrom. The wind resistance of the wheel is reduced.
Lastly, Maxxis state this is an easier system to install and may reduce the chance of damage when removing a tire.
Because the sidewalls 53 of the rim 50 have a flat inside and outside, there is no flange extending from the sidewalls 53, so that the installation of the tire 10 to the rim 50 is easily and quick.
(2/4 Update) Additionally, when ‘breaking the bead’, the tire is more easily removed due to the shape of the rim.
When the tire 10 is broken, because the sidewalls 53 of the rim 50 do not have any flange, so that the tire 10 can be easily removed from the rim 50. The lips 13 of the tire 10 and the sidewalls 53 of the rim 50 are not easily damaged, so that the life of the tire 10 and the rim 50 is prolonged.
I’ll say what we’re all thinking again… proprietary system. This is an awfully specific tire shape and rim shape, I don’t think this tire would work on a regular rim and I don’t think the rim would work with any other tire. I’m sure we’ll see a rim patent sometime soon, as well.
This type of system probably won’t be for everyone, especially the people that don’t like proprietary systems. As a side note, the justification of these types of proprietary systems is that they will almost always work better than generic systems. A bunch of engineers didn’t design this system to be worse. That being said, the acceptance of proprietary systems in the biking world is… low. We all want better systems, but we don’t want them at the cost of buying freedom. It’s quite the conundrum for these manufacturers.
But like I said before, maybe it’s just the loudest that don’t like proprietary systems. If there was any manufacturer that I’d buy a system from, it’s Maxxis. I buy their tires anyway, and a matching rim might be pretty advantageous if this makes it to the mountain bike world.