Originally Posted by
cyccommute
Not sure what or who ChemES is but I find your description hard to believe. Even if the rim were at the boiling point, you would have to get water into the rim which would be difficult considering that the water is cooler than the rim which means the water would vaporized before it got into the rim…think water drops on a hot skillet. If the water did happen to get into the rim, it would quickly cool the rim below the boiling point so the whole system couldn’t be “live” any more.
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Overheating wheels on a downhill is a user error. I don’t check my rims after (or during) a downhill because I know that I haven’t overheated them. Braking on a bicycle should be down in short, hard pulses rather than a long sustained pressure.
So, you've never heard of a chemical engineer being called a Chem E; you missed the part about going through a ford, which let water get into the rim; you skipped the part about water from my fingertip sizzling on the hot rim; you're conflating dynamic heat transfer (heat going through the rim from the brake surface) with equilibrium thermodynamics; and you've never overheated a bike wheel on a downhill; and you don't mention ever seeing or hearing about an overheated rim leading to a tire blowout.
Remind me why I should consider your opinion on how hot a bike tube can get "informed?"