Ive had an ebike for several months, putting 250 miles on it. I've inflated the tires once since receiving the bike...100 miles ago.

Today, a couple hours after a ride I heard a loud BANG, went to investigate, and found my bike on the ground and the front tire's tube exploded.

What happened? The bike was in the sun, but the temp was only 72 degrees at the time.

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  • In order for the tube to fail explosively like that the tire must have failed. (Much less likely, the rim itself failed.) You should check the tire and see where/how it failed. Did the bead pop off the rim? Did the tire split? – DavidW Jun 18 '19 at 3:12
  • Was there anyone around? I remember a spate of "flat tyres" caused by bored school children with pointy compasses and idle hands. – Criggie Jun 18 '19 at 11:30
  • @DavidW - Actually, it's quite likely that the tire simply slipped off the rim. I've seen nearly the identical scenario several times in group rides. One time I got to watch it -- the tube bulging out between tire and rim and popping, while sitting in the sun after a morning ride. – Daniel R Hicks Jun 18 '19 at 16:40
  • @DanielRHicks That's what I meant by "bead pop off the rim" since the tube isn't going to squeeze out from behind the tire if the bead is properly seated. – DavidW Jun 18 '19 at 16:47

For a tire with a tube to explode the tire must have failed to contain the tube. This usually happens two ways:

  1. The tire slipped off the rim (most likely)
  2. The tire structure allowed uncontrolled expansion of the tube (a hole in the tire)

I suppose it's possible to blow through the rim but there would have to be serious easily visible damage to the rim to allow this - very unlikely.

For a tire with no other issues (correctly installed, properly inflated and good tire integrity) sitting in the sunshine will not make the tire blow.

If the tire was not seated properly, over inflated or marginal tire integrity but still working, warming in the sun may exacerbate an existing issue and allow uncontrolled expansion.

Bottom line: Check your tire for damage. Install a new tube, make sure the tire is seated correctly and ride on.

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  • The tire sitting in the sunshine WILL make the tire slip off the rim, as the sun unevenly warms the tire. – Daniel R Hicks Jun 18 '19 at 16:41
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    @DanielRHicks In 20 years of group rides, with bunches of bikes parked outside a pub in the summer sun while we have lunch, that has literally never happened. If a 15 degree heat differential will dislodge the bead, then I will argue the tire wasn't properly seated in the first place. (Or the tire was badly over-inflated.) – DavidW Jun 18 '19 at 16:50
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    @DanielRHicks To clarify, are you saying that any bike sitting in the sun with correctly installed and inflated tires with no defect will have it's tires blown off if there is a shady side to the tire? What kind of uneven warming is needed to blow off a tire? – David D Jun 18 '19 at 16:54
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    @DavidD - I suspect it's peculiar to certain tire/rim combinations. The cases I've seen were mainly lightweight road bikes. And I'm guessing the uneven warming involves heating the top (more exposed) part of the tire more than the bottom, causing uneven expansion. – Daniel R Hicks Jun 18 '19 at 17:01
  • @DanielRHicks Good point - information on which tire/rim combinations have issues would be a great add. – David D Jun 18 '19 at 17:14

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