In this article, we’ll be discussing a Tire Inflation Device by SRAM, US publication 20210094369. The publication date is April 1st, 2021 and the filing date is Sept. 28th, 2020. This patent hasn’t been granted yet.
This is pretty simple, or this will be a short article. This has a road bike pictured, but this could definitely be used on a mountain bike, especially the smaller ones.
Brief Summary (tl;dr)
SRAM are developing an air deflector to be used inside a tubeless tire. The air deflector deflects air away from the tread (radial) part of the tire, preventing the beads from moving inward (axially) and allowing for easier bead seating. This design is specifically for people that aren’t using compressed air.
First, let’s define three terms: axial, radial, and circumferentially. Axial is the direction through the axle. Radial is the direction perpendicular to the axle rotation, so it’s just up, down, forward, backward, etc. Circumferentially is the direction around the tire, so basically just a circle.
According to SRAM, there’s an issue with conventional tubeless filling system:
When airflow is introduced through a conventional tubeless tire air valve, air outputs out of the air valve radially to a circumference defined by a bicycle wheel. Thus, the airflow impacts a tubeless clincher tire radially and generates a radial force on the tubeless clincher tire. This radial force may prevent the tubeless clincher tire from seating in bead walls of a rim during installation of the tubeless clincher tire on the rim.
In short, they’re saying flow coming through the valve is directed to the tread part of the tire, therefore applying a force in the wrong direction of where the bead will seat. This effectively stretches the tire radially, causing the beads to move axially inward.
I’ve always had issues with seating beads, especially with the DH tires I use. I guess I’ve never thought the direction of flow may impact seating efficiency. This one is pretty insightful.
The intended novelty of this one is the use of a body (deflector) attached to a valve, to deflect air using one or more walls of the deflector. This design hasn’t been granted as novel as of the publishing date. Honestly, this seems like an extremely broad novelty claim. I’d bet they’re going to have to dial this back a little bit, and ad some limitations during prosecution. But, I’ve never seen this before, so maybe it’ll fly right through the USPTO, idfk.
SRAM say they want this device to be used for people not using compressed air, to help seat beads and fill tubeless tires.
Seating the tubeless clincher tire may require a high constant … [using] compressed air [from] an air compressor. In many situations, however, a bicycle user does not have access to a compressed air source.
Their solution for this situation is to supply air circumferentially, rather than radially. This should prevent the issue of the tire bead shifting axially, away from the bead.
A tubeless clincher tire may be easier to seat when the air output out of the air valve is directed circumferentially relative to the rim, instead of radially.
This one isn’t very complex. Figure 3 shows the primary design for this new deflector device, showing a cross-section. This is mirrored to the other side, shown in figure 5.
Figure 8 shows a side cross-section and how the air will flow through this device. Note how the air is directed outwardly away from the tread part of the tire.
Figure 13 and 14 show the same idea, but with structural supports. SRAM say this design can be made of a compliant material shell and steel supports to “prevent the deflection device from collapsing”
As an example, the deflection member 182 may be made of rubber, and the structural supports 250 may be made of a steel.
Figure 15 shows another design where the deflection device is attached to the rim, not the valve.
…the deflection [device] may be attached to the rim 122 and not the valve 137. In such an embodiment, the air deflector 150 may not include the attachment portion 180. The deflection [device] 182 may include, instead of or in addition to the guide vanes 260, one or more air diverters, air wings, air spoilers, and/or other types of air guides.
Figure 16 shows the weirdest design. It’s full of a lattice structure to keep the deflection device from collapsing under pressure.
The figures below show a few more examples of the design, which look like smaller profiles.
My initial thought is about wheel vibration. Will this be light enough not to cause a vibration at high speed? I’m also very curious to see if this actually improves bead seating. If this works as described, I’d think about investing in these, especially for DH tires.
SRAM, you’re more than welcome to send me a pair of these. I’ll be the judge. 😊