I’ve been wondering about that. We have a good bit of broken glass in the alley my garage is on. That’s my best guess, but I can’t imagine what scenario could actually lead to a bit of glass gouging through that much rubber. And then for it to not be noticeable until after a 20 minute ride, and for the glass to fall out of the hole? Seems a bit implausible.
Can you please elaborate? My naive thought is that it’s small enough that I could patch or plug it and be able to at least ride for a few days til I can replace the tire.