dijos

I mean in the literal sense, do they stay at a lower temperature in the sun? I have a black and grey bag, and the contents get pretty hot in the summer here (it's freaking hot+the sun is incredible) I also sweat my behind off. I was thinking of avoiding black and thinking about the overall impact of having a lighter color (like red) or way light( like white).

any thoughts on this?

Sekt

Black will definitely get hotter, and anything inside will get hotter as a result. On a hot day, a lighter coloured bag probably wont make a great deal of difference when it comes to sweat.

wearyourtruth

as far as sweat on your back i doubt it will have much effect, since the main source isn't the heat of the bag but the lack of breathability between the bag and your back

as for the contents, heck yes it will make a difference, depending on how long it's out in the sun. if you never ride more than 10 minutes it might not make much of a difference but if you are out in the sun for hours then it totally will help keep the stuff inside cooler

garagegirl

If you do try it, go for white. I would imagine Red or something similar will still absorb a fair amount of light/ heat compared to white. But your back will still get sweaty, you're wearing a giant plasticy object.

EyeRobot

I had a white bag. It's brown now.

operator

lolcats

doomkin

personally i think all the black vs white stuff is bull****.

for example, canon claims that they make their telephoto lens white so that there will be less thermal expansion when their lenses are exposed to the sun. now, if black lenses expanded and distorted images when exposed to massive amounts of sunlight, it'd be a pretty well known fact. but it's not, because its a non-issue.

basically, unless you're taking cars and bunkers, color doesn't really matter that much. thermally.

Daijoubu

It's a fact, go outside on a sunny day and grab yourself a black shirt and white tshirt, leave it a couple minutes and see which one is hotter

doomkin

I had heard (via my high school physics teacher) the black clothes will keep you cooler than white clothes. Is this true?

An extensive and detailed study (Walsberg, Campbell, & King, 1978. J. Comp. Physiol. 126B: 211-222) examined different colors of bird plumage under different temperature conditions--with the added wrinkles of examining whether the plumage was fluffed or flattened, and varying the wind speed.

Under cold conditions with no wind speed, black, flattened plumage held in heat the best (though barely, compared to fluffed black plumage). Under hot conditions with no wind, white, fluffed plumage let heat escape the best. Both pretty logical findings.

But once the wind picked up, the results changed dramatically. With even a modest wind (anything above 3 m/s, or about 7 m.p.h.) fluffed white plumage exhibit the lowest net heat loss. This explains the large number of arctic animals that are fluffy and white. It's not just camouflage.

At high temperatures, as I say, white is best at not transmitting solar/ambient heat to the skin when windspeed is zero (only barely better when fluffed). However, with an increase in windspeed (again anything above 3 m/s), fluffed black plumage is the best at reducing the amount of heat transmitted to the skin. Flattened black plumage is the worst in terms of heat gain no matter what the windspeed.

What this means is relatively straightforward: black clothing absorbs sunlight and the heat radiating from your body, but if it is loose-fitting, and there is wind, the wind convects the heat away faster than it is absorbed. White clothing reflects sunlight, but also reflects internal heat back towards your body, so the net effect under identical conditions is less cooling than if you wore black. While it's true you don't often find fluffy black animals in deserts, you don't find many white animals, either--typically you find animals that blend into the background. So it appears that if heat gain and camouflage are in conflict, the need to avoid predation outweighs other considerations. On the other hand, desert-dwelling nomadic people such as the Tuaregs wear loose-fitting black clothing, and have been doing so for a very, very long time. If there were an advantage to wearing white clothes, you'd certainly expect they'd have figured that out by now.If you are packing for a trip to the desert would it be better to pack light or dark clothes? The answer is not a simple as you might think, as Don and Yael discuss.

Link.

Basically it states that in a static test, then yes, black warms up faster than white. However, if the black is fitted loosely and there is wind then it cools faster than white.

I read this as saying that if you're using a loose fitting messenger bag, over say a tightly drawn back pack, and you're moving along quickly on your bike instead of walking down the street, then the fit of your bag and amount of wind you're generating will produce a cooler ride.

schnee

A messenger bag is not 'fitted loosely' to the contents, and doesn't have the same airflow. Also, bag contents do not have the same heat regulation systems of humans (i.e. they don't sweat). The situations aren't the same at all.

Be very careful of taking a scientific conclusion for one thing and applying it too broadly.

danish

just don't put mayonnaise in your bag and you'll be fine.