The Smell of Molten Projects in the Morning

Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.

The New Hotness

  • Primo Comet vs. Green Glass Chip: Kevlar FTW!

    The gashes don’t look like much:

    Primo Comet gash - tread view
    Primo Comet gash – tread view

    Not even from the side:

    Primo Comet gash - side view
    Primo Comet gash – side view

    When they happened, I knew where to look, because the Kevlar-belted Primo Comet had two conspicuous bulges surrounding debris jammed between the tread and the carcass along the sidewall: the gashes were wide open!

    Much to my astonishment, the tire hadn’t gone instantly flat.

    Some screwdriver probing in the leftmost gash produced this nasty glass chip:

    Primo Comet gash - chip side view
    Primo Comet gash – chip side view

    AFAICT, the smooth side slid over the internal Kevlar belt as the edge sliced between the rubber tread and the carcass. I think the top entered first, with the somewhat crushed end hitting the pavement on each revolution:

    Primo Comet gash - chip edge view
    Primo Comet gash – chip edge view

    The other gash emitted a somewhat smaller chip.

    I rode over something crunchy, most likely the remains of a beer bottle, in a shaded section along Rt 376, and we stopped a few driveways later to diagnose a once-per-revolution thump from the front tire. The tube still wasn’t losing pressure, even after extracting the glass, so I continued the mission; it was a fine day for a ride!

    I later filled those gashes (plus a few others) with silicone rubber to keep grit out. It’s surely a feel-good gesture, but maybe it’ll help the tire reach the end of its tread life.

    You can judge our “riding environment” by the tire’s condition …