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[Closed] Brake disc damage (mtb)

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[#9917004]

Story on mbr page about guy in Austria laying his bike down after a decent and setting the grass alight.

I'm struggling to see how it's possible and if it did happen how it got out of hand so quickly he couldn't stamp it out.

Obviously has to be very hot but surely the disc will get rid of most of that heat quickly.


 
Posted : 29/03/2018 11:21 am
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I got properly branded on the calf once by a mates disc leaning against me. Looked cool for a while till it went shabby!


 
Posted : 29/03/2018 11:29 am
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Tell that to the scar on my leg.

Bone dry grass can burn and spread really quickly, especially if theres a bit of wind.


 
Posted : 29/03/2018 11:43 am
 Drac
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I branded my leg on a disc too when in the Apls, not convinced the heat would stay long enough to light dry grass though.


 
Posted : 29/03/2018 11:46 am
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I was kinda skeptical, thought maybe he'd stopped for a smoke, but I checked the ignition temperature of paper on Wikipedia (on the assumption that dry grass would be similar), and it can be as low as 200 C, which surprised me. It is possible, I guess.


 
Posted : 29/03/2018 12:08 pm
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I could see that happening, maybe not in the wet soggy UK, but if the grass is dry it doesn't take much to ignite it, and it can spread faster than you think.


 
Posted : 29/03/2018 12:20 pm
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Found a PhD thesis which showed dessicated grass failed to ignite on an exhaust manifold at approx 250C but fid ignite at +450C. How long will a disc hold peak temp before falling below 250?


 
Posted : 30/03/2018 9:31 am
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You have too much time on your hands! Lol!


 
Posted : 30/03/2018 10:17 am