In this article, we’ll be discussing a Bash Guard Device and System for Bicycle Components by SRAM, US publication 20220227442. The publication date is July 21st, 2022 and the filing date is Dec 20th, 2021. This isn’t granted yet.
I’m watching Rampage as I’m writing this so excuse any nonsensical ramblings or errors. That shit is very distracting, especially Reed Bogg’s mic-up. Lol.
Brief Summary (tl;dr)
SRAM are developing a bash guard/chainring system, where the bash guard mounts directly to the chainring through the lightening holes of their modern direct-mount chain rings. That’s about it.
Background
As far as I’m concerned, there are two primary bash guard options. The first is from yesteryear that most of you old farts will recognize – the bash ring. The bash ring is exactly what it sounds like; it’s a ring that mounts around your crank/chainring, rotates with your chainring, and sits lower than your chainring to protect it. If one edge gets too fucked up, just turn it 90°, and you’ve got new bash guard. Interestingly enough, it seems as though some manufacturers are still making these things.
The second is the more modern version, which attaches to the ISCG mounts around the bottom bracket. Same concept, yet is static relative to the crank.
After doing some digging, there are a few similar designs out there compared to this SRAM design. In particular, this one on Bikerumor from 2014 shows a two-piece bash guard mounted to a 104BCD chainring from this dude Joe Rogers out of Texas. SRAM are going to have to navigate ideas like this if they want to get this granted.
Intended Novelty
While this isn’t granted yet, they’re basically trying to protect the idea of a bash guard attached to a chainring, and the bash guard protects ‘…less than all teeth…’ of the chainring. In my do-not-sue-me-this-isn’t-a-legal-opinion opinion, the Joe Rogers ideas above is exactly this. They’re going to have to adjust or dig into their dependent claims.
Why
Obviously, this is an attempted improvement to the very-common placement of a frame-mounted bash guard. SRAM says this shit just don’t cut the mustard:
A bash guard mounted to a frame mount may not rotate with the chainring, thereby potentially interfering with the operation of the bicycle drive train and/or providing imprecise protection of appropriate elements.
They also say this design provides a ‘ready-protected’ chainring, is easily removable, and can be removed without disassembling the crank.
The present disclosure may integrate the bash guard into an outboard side of the chainring, which may allow a user to have a ready-protected chainring. The bash guard may be easily removed to provide a fully functioning chainring. Further, the bash guard may be removed without removing the crankset/crank assembly.
While they don’t say it (maybe they do somewhere), I’d also like to point out that this design may also prevent chain drops.
What
FIG. 2 shows an exploded view of this new bash guard/chainring combo. There are two primary components to this new guard – the guard 204 and the backplate 206. The two components are fixed to one another with a screw through a hole in the chainring. God damn SRAM documents have the best figures.
SRAM mention the guards can be made of a number of materials such as “…carbon, plastics, polycarbonate, metals such as aluminum, etc.).”, but they specifically mention an injection molded glass-filled nylon, which is probably a good choice. A softer plastic, compared to a hard metal, is designed to deform and absorb damage. A metal part would be much more resilient, but will transfer much more energy to your frame, and that ain’t good. Bash guard = cheap. Frame = expensive.
FIG. 5A shows what the chainring may look like. It’s got four equally-dimensioned sections with holes, but as we can see in FIG. 5B, these can only be installed in two positions at surfaces 408, which are little recesses/flanges.
This may be obvious, but after going through the current lineup of chainrings, it looks like this bash guard may require a new chainring, and won’t fit on an existing ring, but please correct me if I’m wrong – I may have missed one somewhere out in the ethos.
FIG. 3A and B show the guard installed on the chainring, which effectively straddles the debossed portion 218. As an aside, the debossed portion is a joggle (or double joggle) that provides an additional level of strength. You’ll see this on basically all chainrings these days. Fwiw, flanges and joggles have been used for decades to improve the strength of stamped parts by simply changing the shape of the metal very slightly.
The above images show some holes at the end of the bash guard. I can only assume these are lightening holes, but I wonder if they also provide some level of impact absorption or can break-away due to severe impact. Breaking shit is a great way to dissipate energy (see modern F1 or Indy cars).
FIG. 4C shows a close shot of the bash guard showing the extruded portions that go through the chain ring. It’s possible the extruded part of this design could be part of the novelty, because these extrusions offer a much larger surface area for impacts compared to just mounting the bash guard directly to the BCD locations.
Or, they can say something along the lines of ‘…the bash guard mounts don’t share an axis with anything else…’. SRAM, I’ll be waiting for my cheque.
FIG. 7 shows a cross-section of the guard installed on the chainring, which is probably what we all want to see at this point. It’s pretty simple – the backplate goes on one side of the chain ring, the bash guard goes on the other side of the chain ring, and you bolt it together, that’s about it.
FIG. 10 shows another variation of the same idea, but this one doesn’t have any backplates. The guard is mounted directly to the chainring. It sounds like this one is going to be a bit for flexible, where the holes/pockets/recesses allow for multiple shaped and mounted bash guards.
“…may allow for different numbers, sizes, and/or shapes of bash guards to be used with a single chainring 1002.”
Conclusion
It seems as though this isn’t a ground-breaking new idea, but more of a reinvention of an older idea for modern systems with new technologies. Modern chainrings have complex holes, and SRAM are simply taking advantage of their chainring design. The industry has basically gotten rid of BCD holes in chainrings (due to direct mounts), so now they need to come up with another solution to mount a bash guard, and this is what they’ve come up with.
If this works well, and is adopted more broadly, could this suggest a step toward the removal of ISCG mounts around the bottom bracket? It may seem minor, but removing any complexity such as this can simplify the design and manufacturing process.
Lastly, I’m going to bet we’ll see this on the DH bikes soon, if we haven’t already and I just missed the spy shot. That seems to be the most appropriate application.
Have a good week. The cold is coming to Colorado…
Looks to me like the Joe Rogers design is mounted to the crank, sharing the mounting points with the chainring – same as the old bash rings, just with partial coverage.
The SRAM design would be useful for direct-mount (splined) chainrings that don’t facilitate sharing of the mounting interface.