Not an isolated incident ... an eMTB did the same thing in my neighborhood last week. Didn't see it myself, but a friend saw it and posted video on fb and my wife saw the aftermath. Guy was riding along through an intersection when the bike exploded underneath him, and the bike continued to spit sparks and flame for quite a while after. If it had been on a singletrack trail on a breezy August day, the fire would have been out of control in seconds. I used to think these things should only be allowed where motorized bikes are allowed, but now I'm beginning to think they shouldn't be allowed off streets (I can think of a lot of paved bike paths bordered by heavy brush). At least the motorcycles have spark arrestors.
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I'm guessing this is a problem only with the lower-end products, but I saw a nameless eMTB on my local trails the other day, so people aren't only riding Specialized Turbos etc. Can't exactly post signs that say: "No e-bikes permitted unless built by Specialized or Trek."
As far as the Li-Ion batteries in lights ... even if they experience catastrophic failure, they're not going to put out flames like these combusting bikes are doing.
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