# Ok to leave carbon bike in hot car all day/ (Will it assplode?)



## RJP Diver (Jul 2, 2010)

On an upcoming trip I'll need to leave my car parked for a full day, and would prefer (from a theft-prevention standpoint) to keep my bike IN the car vs ON the car. 

Summer + Black car + black interior = hotter'n hell. 

Will my Cervelo assplode?


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## Charlie the Unicorn (Jan 8, 2013)

I know I've been advised against it. I'm sure it has been done before, however.


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## Stumpjumper FSR (Aug 6, 2006)

It won't melt!

Technical FAQ: Carbon in the sun - VeloNews.com


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## aureliajulia (May 25, 2009)

Deflate the tires when you do.


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## tlg (May 11, 2011)

The carbon fiber itself is no problem. We use carbon fiber products in heat treating furnaces up to 3000°F. 
On your bike, it's the epoxies and paint you'd have to worry about first. But as the article above explains, those are good to over 180°. 
If you have any plastic do-dads, flashlight mounts, water bottle cages, perhaps those could be become soft or brittle in the heat.
One thing to watch out for, is the heat will make the lube in your chain less viscous, and it might seep out of the rollers a bit.


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## SauronHimself (Nov 21, 2012)

Carbon has the highest melting point of any element, so I think you're okay. Besides, it's carbon and not black powder.


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## RJP Diver (Jul 2, 2010)

SauronHimself said:


> Carbon has the highest melting point of any element, so I think you're okay. Besides, it's carbon and not black powder.


Was more worried, I suppose, about decals, paint finish, adhesives on bar tape, etc.


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## JCavilia (Sep 12, 2005)

SauronHimself said:


> Carbon has the highest melting point of any element, so I think you're okay. Besides, it's carbon and not black powder.


Melting point is correct, but not very relevant, since the material is not simply carbon, but a composite of carbon and a plastic resin that is affected by much lower temps. But as others have said, the temps reached in a solar-oven auto are still within the safe range for those materials. Lubricants, other plastic bits, and rubber are a different concern.

RJP, does your car have a trunk? It doesn't get as hot in there as in the greenhouse.


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## tlg (May 11, 2011)

SauronHimself said:


> Carbon has the highest melting point of any element


Sure... if your car is pressurized to 1450psi.


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## Sisophous (Jun 7, 2010)

Temps can reach 150 inside a car. Make sure to park it in the shade, under a large tree if possible and put up window shields to keep it cooler and block people from seeing what is inside the car. Remove your computer and battery operated bike light if you have one. I would also leave the windows open about a half inch unless you are expecting thunderstorms. If the temp does not go over 100, everything else should be fine.


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## tom93r1 (Jul 19, 2009)

Plastics inside cars start to have issues after many months of being parked outside in the direct sun. I wouldn't worry too much about a carbon bike for a single day. I might relieve a little pressure from the tires but that's about it.


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## Jay Strongbow (May 8, 2010)

JCavilia said:


> RJP, does your car have a trunk? It doesn't get as hot in there as in the greenhouse.


....and give your reason is theft prevention I'd definitely use the trunk if possible. 
I've never tried either but would imagine breaking a car window is a lot easier than picking a decent bike lock so the heat issue aside the back seat might not get you much in terms of theft prevention.


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## aureliajulia (May 25, 2009)

If you have one or two of those heat/light reflective shields designed to provide shade in the front window, you can lay it/them over your bike. Keeps the bike much cooler, and shields it from view if you do it right.


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## Spike Chili (Apr 18, 2011)

A carbon bike left in a hot car will assplode like a popcorn kernel and the carbon will create a new precious diamond in its wake...at least thats what I heard on the internet...


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## vautrain (Mar 1, 2012)

tlg said:


> We use carbon fiber products in heat treating furnaces up to 3000°F.


You heat treat _furnaces_? Using carbon fiber? Wow!


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## Rekless1 (Aug 23, 2012)

If your cars seats and dash board haven't melted yet, I think your bike will be just fine.


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## mpre53 (Oct 25, 2011)

I'd be more worried about a smash and grab than an assplosion.

I have a bunch of graphite fishing rods. Carbon fiber, filler scrim, and various resins bonding them. I've left them inside my vehicles on the hottest days, and never had one warp. And I would guess that there is less carbon fiber material in them than in a bike frame.


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## Sisophous (Jun 7, 2010)

Spike Chili said:


> A carbon bike left in a hot car will assplode like a popcorn kernel and the carbon will create a new precious diamond in its wake...at least thats what I heard on the internet...


maybe he should leave the air conditioning running


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## anotherguy (Dec 9, 2010)

Jay Strongbow;4416740
I've never tried either but would imagine breaking a car window is a lot easier than picking a decent bike lock so the heat issue aside the back seat might not get you much in terms of theft prevention.[/QUOTE said:


> As an aside, bolt cutters > lockpicking for bike thieves.


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## RJP Diver (Jul 2, 2010)

Jay Strongbow said:


> ....and give your reason is theft prevention I'd definitely use the trunk if possible.
> I've never tried either but would imagine breaking a car window is a lot easier than picking a decent bike lock so the heat issue aside the back seat might not get you much in terms of theft prevention.


I have an Audi Q5 SUV, so no "trunk" per se. There is a pull-over shade and the rear windows are tinted, so somewhat less likely to be spotted "in" rather than "on" the car. Parking in a fairly safe/busy area so not terribly worried. Just figured that on the roof or bike'locked it's too attractive/easy for someone walking by to be tempted. (Smashing a window will get attention, seeing someone trying to get a bike off the roof or "unlocking" it with tools will rouse little suspicion.) Plus, I'll be leaving it in a marina area (going diving for the day) and anything left outside for several hours is fair game for seagull target practice.


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## Bikes4Life (Jul 26, 2013)

The trouble point is at around 200C. In most cars the temperature won't reach over 50, it should be able to tolerate the heat..


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## BikesOfALesserGod (Jul 22, 2012)

Don't leave your bike in the car on a hot day! I'll call BPS on you!


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## jjcools (Jun 28, 2011)

Got it, what marina was that again? I could see myself on a Cervelo...


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## jjcools (Jun 28, 2011)

Especially an RCA!


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## Chainstay (Mar 13, 2004)

If you inflated your tire to 110 psi when the temperature was 15C (about 45F) and the temperature in the car rises to 45C (about 120F) your tire pressure will increase to 121 psi.


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## velodog (Sep 26, 2007)

Isn't carbon fiber cured in an oven?


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## Fai Mao (Nov 3, 2008)

velodog said:


> Isn't carbon fiber cured in an oven?


That is kind of the question. Is it hot enough to un-cure it?

I don't ride a carbon-fibre bike so this is not that big an issue for me but I don't think the temperature would get hot enough to affect it. I think it is the UV light more than the heat that is an issue and that would remain the same.

I would be real tempted to find some way to take the bike with me rather than leaving it in a vehicle though


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## velodog (Sep 26, 2007)

Fai Mao said:


> That is kind of the question. Is it hot enough to un-cure it?
> 
> I don't ride a carbon-fibre bike so this is not that big an issue for me but I don't think the temperature would get hot enough to affect it. I think it is the UV light more than the heat that is an issue and that would remain the same.
> 
> I would be real tempted to find some way to take the bike with me rather than leaving it in a vehicle though


Yep, it don't get warm enough in there to un-braze steel.

But I really think that this is being un-necessarily worried about. These are machines that are meant to be used in the elements, and while they maybe could break in an accident, I can't imagine that a manufacturer would sell a product, such as a bicycle, that would be adversely affected if subject to being left in an automobile.

I mean, we're talking about a bicycle not a poodle.


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## JasperL (Aug 21, 2011)

"*Smashing a window will get attention*, seeing someone trying to get a bike off the roof or "unlocking" it with tools will rouse little suspicion."

Don't count on it. Good thieves can smash windows while attracting little attention. We run/exercise at a local park and a guy broke into a dozen or so cars over 3 weeks, most often during the evening after-work "rush" hour for this place. One of the victims was with us - we were in a group, just a few yards from the parking lot, people coming and going the entire time, and the guy did a smash and grab with her purse. Nobody noticed a thing till she went to her car to leave. They only caught him when he used a stolen card at a gas station with security cameras - not in the act.


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## Fai Mao (Nov 3, 2008)

velodog said:


> Yep, it don't get warm enough in there to un-braze steel.
> 
> But I really think that this is being un-necessarily worried about. These are machines that are meant to be used in the elements, and while they maybe could break in an accident, I can't imagine that a manufacturer would sell a product, such as a bicycle, that would be adversely affected if subject to being left in an automobile.
> 
> I mean, we're talking about a bicycle not a poodle.


It probably doesn't get hot enough to change the heat tempering on my aluminum bike either. :} 

Not every bike I have is steel. Just none are CF.


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## woodys737 (Dec 31, 2005)

Chainstay said:


> If you inflated your tire to 110 psi when the temperature was 15C (about 45F) and the temperature in the car rises to 45C (about 120F) your tire pressure will increase to 121 psi.


 15C=59F and 45C=113F.


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## PaxRomana (Jan 16, 2012)

tlg said:


> The carbon fiber itself is no problem. We use carbon fiber products in heat treating furnaces up to 3000°F.
> On your bike, it's the epoxies and paint you'd have to worry about first. But as the article above explains, those are good to over 180°.
> If you have any plastic do-dads, flashlight mounts, water bottle cages, perhaps those could be become soft or brittle in the heat.
> One thing to watch out for, is the heat will make the lube in your chain less viscous, and it might seep out of the rollers a bit.


I had a friend melt the epoxy on his bike by leaving it in his car on a hot summer day. It was eventually warrantied, so perhaps it was a faulty epoxy job.


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## velodog (Sep 26, 2007)

Fai Mao said:


> It probably doesn't get hot enough to change the heat tempering on my aluminum bike either. :}
> 
> Not every bike I have is steel. Just none are CF.


Sorry, I assumed.

But mine are all steel. My wife has an aluminum Vitus though.


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## redondoaveb (Jan 16, 2011)

Me thinks this would make a good "Mythbusters" episode.


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## aclinjury (Sep 12, 2011)

The tires (for bicycles) will be affected by the constant cycles of heat and cool down. Over time, the rubber will delaminate from the carcass prematurely. Auto tires can withstand the heat cycles more.


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## High Gear (Mar 9, 2002)

Your tubes will pop before anything happens the the bike....


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## Fai Mao (Nov 3, 2008)

redondoaveb said:


> Me thinks this would make a good "Mythbusters" episode.


I do not know about CF but aluminum is "cured" or tempered at something like 450 F. for three hours or that is what the guy at the Cannondale plant I toured years ago said, assuming I remember right. Steel is brazed or welded at much higher temps than that. I imagine a mono-cot CF frame is baked at a temperature of least 400 to 500 degrees F. If it is 400 degrees inside a car you've probably got more pressing issues than the bike - like whole car starting to burn. So I don't think that Myth Busters would take something like this.

The issue with CF is not the heat so much as the UV and that would remain constant. That is another reason that a CF bike should be covered if it is left in the sun and I would recommend that in any case for any bike regardless of materials.

Other than that the only issue might be the formaldehyde that out gasses from the plastic parts in the interior of the auto when it gets hot but once again. I don't know.

There are lots of potential issues with CF bikes I just don't see this as one


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## Jajo (Apr 12, 2013)

Putting your bike in the car where it can be seen is a good way to see how good your insurance policy is.


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## Waspinator (Jul 5, 2013)

tlg said:


> The carbon fiber itself is no problem. We use carbon fiber products in heat treating furnaces up to 3000°F.
> On your bike, it's the epoxies and paint you'd have to worry about first.



Ummm....

Not trying to be a jerk here, but it sounds like you don’t understand how carbon fiber works. The “epoxies” are half of the equation. Any carbon fiber structure is a “composite” of the carbon fibers (usually woven into a carbon fiber cloth) combined with the epoxies (a.k.a. resins) that allow the structure to maintain its shape. The epoxy is integral to a carbon fiber structure. In fact, one could even make the argument that the epoxy is more important than the carbon fiber. Technically, the epoxy can be made into a frame all by itself. Use enough of it (or use an exceptionally strong one), and the epoxy frame could be strong enough to ride. The carbon fibers are simply there to strengthen the epoxy.

In fact, you’ve heard of FRP, right? It’s plastic that has fibers in it to reinforce it. From a structural standpoint, it is conceptually nearly identical to carbon fiber (with some differences: 1. the materials used, and 2. in FRP, the fibers aren’t typically oriented in any way for directional strength the way carbon fiber is). But the point here is that plastic parts can be made all on their own, _without _fibers to strengthen them.

Weaken (or soften with heat) the epoxy of a carbon fiber frame, and the frame is summarily rendered completely unsafe to ride.


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## tlg (May 11, 2011)

Fai Mao said:


> I do not know about CF but aluminum is "cured" or tempered at something like 450 F. for three hours or that is what the guy at the Cannondale plant I toured years ago said, assuming I remember right.


The Cannondale guy probably meant (or said) 450°C. 
Aluminum is heat treated at temperatures around 800-1000°F (426°-537°C). Heat treating is what makes the material stronger. 
Annealing is the process of softening aluminum, which is done around 600-800°F.


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## tlg (May 11, 2011)

Waspinator said:


> Ummm....
> 
> Not trying to be a jerk here, but it sounds like you don’t understand how carbon fiber works. The “epoxies” are half of the equation. Any carbon fiber structure is a “composite” of the carbon fibers (usually woven into a carbon fiber cloth) combined with the epoxies (a.k.a. resins) that allow the structure to maintain its shape. The epoxy is integral to a carbon fiber structure. In fact, one could even make the argument that the epoxy is more important than the carbon fiber. Technically, the epoxy can be made into a frame all by itself. Use enough of it (or use an exceptionally strong one), and the epoxy frame could be strong enough to ride. The carbon fibers are simply there to strengthen the epoxy.
> 
> ...


Ummmm...
Not trying to be a jerk here, but it sounds like you didn't comprehend what I wrote. 
I design products made from CFC. Used at temperatures to 3000°F. I understand a thing or three.


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## Fai Mao (Nov 3, 2008)

tlg said:


> The Cannondale guy probably meant (or said) 450°C.
> Aluminum is heat treated at temperatures around 800-1000°F (426°-537°C). Heat treating is what makes the material stronger.
> Annealing is the process of softening aluminum, which is done around 600-800°F.


Possibly or I remember it wrong. I have thought for years the temperature sounded a bit low. But what do I know? The nearest I ever got to a degree in science is Library Science

But I think the basic point is still valid that it will not get hot enough in a car hurt the frame from heat.


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## ziscwg (Apr 19, 2010)

JCavilia said:


> Melting point is correct, but not very relevant, since the material is not simply carbon,


I'm trying to imagine some guy coming out of work and have this black goo in the shape of his frame laying in the back of his SUV.


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## S2H (Jul 10, 2005)

Now I remember why I moved to the FB group...


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