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Old 06-07-11, 06:34 AM   #1
gdhillard
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Bike tires and exaust pipe.

Going on vacation with the kid, I had three bikes hung on the trunk mounted rack. After an hour or so, and silently noting a faint burning rubber smell, I then heard a loud "bang". I ignored that also. Stop for gas, checked the bikes, and found I had hung my faithful commuter with the front tire about six inches directly behind the exaust pipe. It melted my tire clean away. New tire and tube and tire strip and r strip already on (ouch) and planning a down turned exaust tip instalation today.
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Old 06-07-11, 07:04 AM   #2
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Wow that is crazy. I know on my diesel pickup if you get in front of the exhaust it will burn the piss out of ya, I'm guessing the same can be said for gasoline vehicles too.
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Old 06-07-11, 07:49 AM   #3
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Wait you ignored burning rubber and a bang while driving?
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Old 06-07-11, 07:56 AM   #4
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That happened to me. Bought a down turned exhaust extension; took care of the problem
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Old 06-07-11, 09:31 AM   #5
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If it cooked the tire off, then it could have overcooked the rims. I'd be a little suspect about that wheel's integrity after that.
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Old 06-07-11, 03:11 PM   #6
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I did that once driving my bike home from college. After that, I always just took my front wheel off and stowed it in the trunk.
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Old 06-07-11, 04:06 PM   #7
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You're not going to use that wheel without a thorough check first, right?
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Old 06-07-11, 04:57 PM   #8
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You're not going to use that wheel without a thorough check first, right?
bah, details . .
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Old 06-07-11, 05:56 PM   #9
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It melted my tire clean away.
The plastic cover over the back bumper? If you mount your new exhaust upside down, you'll actually melt it. It will melt your car. Exhaust pipes... park a low clearance car like a Corvette over a pile of leaves and the leaves will catch fire in a few minutes.

Whenever the subject of global warming comes up, people start babbling about the CO2 cars put out. I've tended to point out that, if you've had an ambulance, fire truck, or big diesel rig drive by, you've probably noticed the "standing in front of a furnace" effect. We have tons of these, plus lots of little cars, belching tons of heat. Your car is a very inefficient heat engine; its entire power output is a small fraction of the raw heat generated from burning gasoline. The act of moving the car actually cools the exhaust gases, but the heat just moves into the engine block and radiates out from there, the oil pan, and the radiator.

Numbers I've heard for **** Cycle efficiency have ranged from 9% to 30%.

Now, think about twice the power of your engine coming out of that little exhaust pipe as pure heat.

Surprised your tire melted? (For that matter, are you surprised big cities are so friggin' hot?)
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Old 06-07-11, 07:37 PM   #10
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I had a similar issue with my trunk mount rack last week. It wasn't my tire that cooked though. It was the clear plastic spoke guard on my back wheel. I melted into something vaguely pretzel shaped.
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Old 06-07-11, 07:39 PM   #11
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Whenever the subject of global warming comes up, people start babbling about the CO2 cars put out. I've tended to point out that, if you've had an ambulance, fire truck, or big diesel rig drive by, you've probably noticed the "standing in front of a furnace" effect. We have tons of these, plus lots of little cars, belching tons of heat.
You are badly needed on a political forum I frequent. Everytime there is a frost they roast Al Gore in effigy. The carbon dioxide fixation has had everyone on BOTH sides of the AGW argument missing the obvious contribution of direct injection of waste heat into the atmosphere. In fact this is only the 2nd time EVER that I have seen it. The first was less than a month ago in the last book of Peter F. Hamiltons sdi-fi trilogy.

H
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Old 06-07-11, 07:45 PM   #12
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I had a similar issue with my trunk mount rack last week. It wasn't my tire that cooked though. It was the clear plastic spoke guard on my back wheel. I melted into something vaguely pretzel shaped.
That probably means the grease in your bearings in that wheel, and the free hub or freewheel has been turned into cement or just crud.
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Old 06-07-11, 08:02 PM   #13
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If it cooked the tire off, then it could have overcooked the rims. I'd be a little suspect about that wheel's integrity after that.
The rim is now heat treated for strength ...
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Old 06-07-11, 08:17 PM   #14
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You are badly needed on a political forum I frequent. Everytime there is a frost they roast Al Gore in effigy. The carbon dioxide fixation has had everyone on BOTH sides of the AGW argument missing the obvious contribution of direct injection of waste heat into the atmosphere. In fact this is only the 2nd time EVER that I have seen it. The first was less than a month ago in the last book of Peter F. Hamiltons sdi-fi trilogy.

H
I actually like to sometimes discuss this stuff in a non-politics form. An Al Gore centric discussion is boring. Pointing out that you are, in fact, surrounded by thousands of contained chemical fires is more useful than crying about funny men in funny suits and arguing over whether or not you think we need more trees, less oil, and global independence, or whatever politics is involved.

It was relevant to the discussion at hand, anyway. Al Gore is not; he drives a Hummer, which is not a bicycle. George W. Bush rides mountain bikes, he can be relevant from time to time.

Though, aside and off-topic, I'm amused a sci fi writer got to this. I've made the argument a few times on slashdot. I've also made the argument that things like solar power will inevitably lead to the increased retention of solar energy on this planet, and its conversion directly into waste heat (all mechanical energy is eventually lost as heat, otherwise we would have perpetual motion; things that move eventually grind to a halt from friction with air/surfaces, converting their momentum to heat, which covers the part of the energy used to do actual work rather than converted directly to heat). I make no assertions as to quantity; solar energy may indeed release less energy into the system than stored chemical energy, either in fossil (long-term, releases ancient CO2) or biofuel (short-term, releases freshly collected CO2 and collected solar energy) form, although I suspect fresh bio-storage will have limiting factors attached to it and would eventually become food for animals and thus release as heat anyway.

Anyway, short version, I take things way too deep and look at every part of the system at once. My previous explanation for this was always that I can simulate the entire universe in my head (it's not difficult, really); but recently I just shrug and tell people I play Go, and let them wonder how the hell that's relevant to anything (it is).

You really don't want to park your bike right next to a camp fire, let alone off the exhaust port of a small furnace. It seems silly to me that refrigerators, ovens, and home generators aren't on a switched vent, where the cooling exhaust (stoves have an exhaust port, and refrigerators have a huge passive radiator on the back; generators have a water pump radiator driven cooling system with a fan if they're in danger of overheating) is pumped out of the house in the summer, and circulated in the ventilation system in the winter. All of these things are massive heat sources, and it would make sense to me to use the generator as a contributor to your electricity usage and heating in the winter time, supplementing both. What the heck do you do with gas furnace exhaust? You pump it outside! You may as well do the exact same thing (burn stuff and heat-sink it to the ventilation system), but try to use the lost waste heat for something... like powering a dynamo?

These things are all hot!
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Old 06-07-11, 08:19 PM   #15
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I'd be a little suspect about that wheel's integrity after that.
That's an interesting point, although the melting point of aluminium is over 900 degrees. It would be pretty hard to imagine a car exhaust getting anywhere near that temperature. I suppose it's possible that the heat could have melted the rim tape, however.
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Old 06-07-11, 08:24 PM   #16
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That's an interesting point, although the melting point of aluminium is over 900 degrees.
Irrelevant. Heating and cooling do funny things to materials. Metals (aluminum is not a metal) are hardened by heating to phase change, then rapid cooling (quenching); metals are tempered by heating below phase change. If my razors get above the boiling point of water, I could mess up the temper and then the steel won't take or hold a good edge.
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Old 06-08-11, 02:54 PM   #17
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Rim seems to be OK. No cracks or warping. Cleaned the melted rubber off, then took another bike to my LBS and got a nimbus armadillo, a new rim strip and a tire strip. I have a few extra tubes at home. Put it all together and loved the new tire enough I went back and bought one for the rear. Fixing the exaust pipe today. Hope to be car free after we move to Roanoke VA next June.
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Old 06-08-11, 09:17 PM   #18
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Irrelevant. Heating and cooling do funny things to materials. Metals (aluminum is not a metal) are hardened by heating to phase change, then rapid cooling (quenching); metals are tempered by heating below phase change. If my razors get above the boiling point of water, I could mess up the temper and then the steel won't take or hold a good edge.
Correct. The rim, spoke, nipple, hub parts, may have been annealed. At the very least I would have someone who knows how to check the spoke tension.

http://en.wikipedia.org/wiki/Annealing_(metallurgy)
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