Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  


Go Back   > >

General Cycling Discussion Have a cycling related question or comment that doesn't fit in one of the other specialty forums? Drop on in and post in here! When possible, please select the forum above that most fits your post!

User Tag List

Reply
 
Thread Tools Search this Thread
Old 03-14-06, 08:54 PM   #1
TheRCF
Da Big Kahuna
Thread Starter
 
Join Date: May 2003
Location: Oahu, Hawaii
Bikes:
Posts: 814
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
"phase change" cooling?

Anyone know about this? Someone asked about the stuff in another forum yesterday and I did a little research. Here is one link:

http://www.ridecool.com/catalog.htm

From the various sites I looked at, it seems that this stuff doesn't actually feel like you are putting something cool on, but rather, when you go past a certain temperature, it sucks up the excess heat so you feel more comfortable.

As you can see from the link, there are various items. But the thing I would be most interested in would be something to wear inside my helmet since, whenever you stop for a traffic light or something, the heat builds up pretty quick, especially if you have been pushing hard (and I have lots of traffic lights).
TheRCF is offline   Reply With Quote
Old 03-16-06, 11:22 PM   #2
DannoXYZ 
Senior Member
 
DannoXYZ's Avatar
 
Join Date: Jul 2005
Location: Saratoga, CA
Bikes:
Posts: 11,600
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
This is a rate equation with respect to time, so you need to work temperatures at various points in time, not just at some arbitrary starting point. Two laws of thermodynamics must be adhered to:

1. heat flows along a gradient, from hotter to cooler

2. total heat does not change, it goes from one place to another, but it is never destroyed

So when you're riding you've got two things to consider. The heat-source is your body and you'll generate a certain amount of heat, BTUs per hour, based upon how much you're exercising. This heat is higher than the outside ambient temperatures so some of it is radiated away. A more significant amount goes into heating up sweat and evaporating it, which absorbs away 540kcal/mole of sweat. A significant factor in radiating and evaporating heat away is surface-area.

As for heat in the helmet, that's a hard one to work with. You've got limited amounts of exposed surface area to radiate and evaporate away heat. I suspect the fastest way to cool your brain would be to have as much surface-area as possible, no helmet at all. we can use that as a 100% control figure. I'm not how to measure how much a helmet blocks at rest at a stoplight. With that figure, we can then compare cooling rates with and without something between your head and the helmet.

The thing is, increasing one cooling method may be counter-productive to the other. using something to faciliate radiating heat away may slow down evaporative cooling and vice-versa... I supposed the best method would be to have something between your head and the helmet that's continually at a lower-temperature than your head AND the outside air... which would require active refridgeration...
DannoXYZ is offline   Reply With Quote
Old 03-17-06, 07:02 AM   #3
cc_rider
Calamari to go
 
cc_rider's Avatar
 
Join Date: May 2005
Location: Falls Church, VA
Bikes: Trek 750
Posts: 3,106
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I'll stick with sweating.
cc_rider is offline   Reply With Quote
Old 03-17-06, 07:16 AM   #4
huhenio
Barbieri Telefonico
 
huhenio's Avatar
 
Join Date: Aug 2005
Location: Albuquerque, New Mexico
Bikes: Crappy but operational secondhand Motobecane Messenger
Posts: 3,522
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Dont forget to bring a towel. Finish the ride, remove sweat, spray yourself with cool water (just like boxers do) like a plant, dry , repeat.
__________________
Giving Haircuts Over The Phone
huhenio is offline   Reply With Quote
Old 03-17-06, 10:56 AM   #5
TheRCF
Da Big Kahuna
Thread Starter
 
Join Date: May 2003
Location: Oahu, Hawaii
Bikes:
Posts: 814
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Yeah, I've thought of those things, but from what I've read, this stuff does work except I don't know how well the helmet stuff works on a bike because of the reasons you gave.

I find the coolmax headcovering I wear works well for me without causing overheating and it keeps my hair from getting all wet from sweat. Of course, that thin covering still allows the air to do it's job. This other stuff I assume is a little thicker and maybe has its own problems. Sure would like to test it though!
TheRCF is offline   Reply With Quote
Old 03-17-06, 04:37 PM   #6
MisterJ
Senior Member
 
Join Date: Jun 2002
Location: Travelers Rest, SC
Bikes:
Posts: 321
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by cc_rider
I'll stick with sweating.

Actually, sweating is phase change cooling if you think about it.
MisterJ is offline   Reply With Quote
Old 03-17-06, 04:39 PM   #7
cc_rider
Calamari to go
 
cc_rider's Avatar
 
Join Date: May 2005
Location: Falls Church, VA
Bikes: Trek 750
Posts: 3,106
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by MisterJ
Actually, sweating is phase change cooling if you think about it.
I know
But why pay extra?

Last edited by cc_rider; 03-17-06 at 06:29 PM.
cc_rider is offline   Reply With Quote
Old 03-17-06, 06:27 PM   #8
DannoXYZ 
Senior Member
 
DannoXYZ's Avatar
 
Join Date: Jul 2005
Location: Saratoga, CA
Bikes:
Posts: 11,600
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Yeah, that's how sweating works. It evaporates on your skin and the phase-change absorbs heat. How a lot of wicking-fabrics work is that they take the sweat that's trapped between your skin and the jersey that normally just drips down the inside, and wicks it up to the outer surface of your jersey. It's evaporated there on the outside and this cools the outer layer of the jersey. which then sucks up heat away from your skin.

Kinda like how a refridgerator works... I'm looking at the vest. For the phase-change bag of liquid to work, the layer next to your skin has to change from liquid to vapor. This absorbs heat next to your skin. Then this vapor needs to be transmitted to the outer layer of the bag where it's converted back to liquid. This gives off heat which is transmitted through the bag to the outer surface. This heat needs to evaporate something on the outer surface. Maybe sweat that's been pumped from between the skin and inner-layer of the bag to the outside somehow?
DannoXYZ is offline   Reply With Quote
Old 03-17-06, 06:45 PM   #9
CastIron
Sensible shoes.
 
CastIron's Avatar
 
Join Date: Aug 2005
Location: St. Paul,MN
Bikes: A few.
Posts: 8,799
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Ya know I've given some thought to those for the motorcycle. Gets bloody hot under all that gear. But I have to wonder: Wouldn't a kidney belt with those gel packs you can freeze/microwave be better for less fuss? Huge blood supply in the area so all you do is help it cool/heat as you wish without having a wind blocking cumbersome vest on. The principle holds nicely when I'm wrenching in my un-heated garage wearing one of those Therma-care jobs.
__________________
Mike
Quote:
Originally Posted by cedricbosch View Post
It looks silly when you have quotes from other forum members in your signature. Nobody on this forum is that funny.
Quote:
Originally Posted by cedricbosch View Post
Why am I in your signature.
CastIron is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -6. The time now is 12:19 PM.