kevlar bead blowout at speed-what happens?

Discussion in 'Cycling Equipment' started by garage sale GT, Aug 31, 2008.

  1. garage sale GT

    garage sale GT New Member

    Jun 6, 2006
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    I have had a wire bead tire completely blow out at 15 mph or so. I was able to stop safely. The completely flat tire stayed on the rim and allowed at least a little control. ​

    Has anyone had a complete blowout with a kevlar bead tire while rolling? What happens? It would seem the tire comes off the rim and you crash. ​

  2. alienator

    alienator Well-Known Member

    Jun 10, 2004
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    It all depends on how tight the tire is on the rim. FWIW, kevlar beads don't stretch signifcantly, but wire beads will. Also, whether or not the bike is easily controllable depends on a few things:
    • Whether the tire is on the front or back
    • How fast you're moving
    • The road grade, crown, and surface
    Be it tubular or clincher, a tire that's gone completely flat is not fun to ride at speed, especially when the squirming of the tire between rim and road really gets going. With both tire types, if you get that total flat in a corner, especially a corner with speed, you'll be lucky to walk away, let along walk away with skin left on your pointy or fleshy bits.

    2 years ago, a braindead driver forced me onto the shoulder of a road (I was moving at about 25 mph or so.) and into a 1-2 inch deep slot in the pavement, a slot that was none too straight. The clinchers died instantly, and when I came out of the slot onto the road, control was something that didn't really exist. The tires had kevlar beads, and the beads stayed seated.
  3. 531Aussie

    531Aussie Well-Known Member

    Apr 11, 2004
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    Nah, I reckon this is very rare, so I wouldn't stress too much about it. When I was younger and sillier, I used to ride 20mm Continental GP tyres pumped up to 150+psi all the time; both with wire and kevlar beads. It's possible that the tyre had side-wall damage, and the blow-out might've taken out some of the bead.

    It doesn't seem to happen as much these days, but if some tyres have been sitting on a shelf for a LONG time, the sidewalls can dry out, perish and crumble. This happen to a cheap Vredestein I bought a few years ago, but I spotted the problem before I inflated it.
  4. Powerful Pete

    Powerful Pete New Member

    May 29, 2004
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    Agree with 531Aussie on this one. This should be quite a rare occurrence that you should be able to spot in regular maintenance. Don't worry about it.