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Cooling Options - Evaporative vs. PCM


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I just came back this past weekend from a ride south. The ride home was only 500km but I suffered severely with overheating. Myself, not the bike. My first mistake was to trust those fellows in the weather bureau which led me to undertake the weekend trip with my ordinary jacket (without liner). I soon had all the vents open but continued to sweat profusely. I simply could not ride without the jacket although the temptation was there. I’ve had tar burn in my youth and still remember how painful it is.


This brings me to the question that I would like some help with. That is to do with cooling options. I have searched this forum and read the responses and comments from fellow riders. I do however have some unanswered questions which I would like to put to you folks for comment.


In summary of what I have read on this forum, there are two options open to me. The first is an evaporative cooling jacket/vest and the other option is a Phase Change Material jacket/vest. The first option seems the more popular but is restricted in effectiveness in higher humidity areas but is the easier ‘rechargeable’ option needing only ordinary water and uses airflow to cool you down. The second option maintains an even temperature and will work for 2 – 3 hours before the inserts require cooling. The cooling operation works with or without airflow.


What I would like to know is:


Evaporative cooling option:


1) At what percentage of humidity is the evaporative cooling vest considered to decline from being effective?

2) Does this vest/jacket wet your clothes either underneath or your jacket you wear over it?

3) Does it still work adequately behind the fairing and windscreen?


Phase Change Material Option:


1) They talk about taking a spare set of inserts with you but how do you keep these cold/ready for use. Surely they run out just like those in the jacket?

2) How do you recharge them if you do not have access to ice or ice water or even if you break is not long enough to chill them again?

3) Is this still effective considering the inserts do not cover your whole body?

4) Do they really last 3 hours? Does performance decline from minute 1 or do they remain effective until the end?


Ignoring the cost, which is considered to be the best option? I would not always have access to ice in small quantities and not sure how to maintain a spare set of inserts for later use.


Any help or advice would be greatly appreciated.



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Humidity isn't the only factor in how effective an evaporative vest is. The other factor is air flow. Moving air will cause more evaporation than still air of the same humidity.

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Just to through more confusion into the mix, there are two designs of evaporative vest out there. One that uses the little crystals (can't remember off the top of my head what they are made of) that absorb water. The other design used a fabric that wicks water into it by capillary action. I had the former and just switch to the latter, which is MUCH better. "Charges" faster, holds more water (but as a result is heaver) and last longer.


People talk about the evaporative system not working in high humidity, but in my neck of the woods 90% summer humidity is common and I still always found them to cool well.


I think the PCM types are better suited for stationary cooling, like say hunting or fishing or something where there is limited airflow. But for on a bike it seems to me the hassle of charging the cooling modules would be more than it's worth when the evaporative types are so simple. Wet and go.

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I use a Thermo-tux evaporative vest. I soak it in water and freeze it when I know I will be riding in the heat here in the East Bay. It stays frosty cold in my saddlebag for at least four hours.


Thermotux also makes a helmet cooler that will fit into the dome of your helmet if you have room.


Mine stays ice cold for about an hour and cools for several hours. It works best when worn over a shirt and under a jacket. It was designed for Soldiers to wear under body armor and is very durable.


Go to http://www.thermotux.com for more information.

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I have and use both types, depending on weather.


Scientific humidity decision point: if I step outside and it "feels muggy" I go with the PC vest, which is most of the time in central Texas.


Took a little 300 mile jaunt yesterday, high temp was about 97 coming back into town in traffic, average was about 92, not too hot, but very humid. I used the PC vest, with all four inserts. I timed their "cooling factor." At about two hours all four inserts were completely melted, cool, but not really cooling. I took the four spares out of the small softsided cooler in the topcase, and put the melted ones in it. Two hours, and it was time to switch. Slushy ice water actually seems to work faster than just ice, but figure out how to keep the cooler from leaking/spilling

dopeslap.gif. The times mentioned were using a mesh jacket; I've said elsewhere that I think the PC material will remain cold longer with a liner or not-vented jacket, although I've not actually tested my theory...the inserts on the back always last longer than the front, adding science to my idea, no?


The PC material will refreeze in very cold slushy water in about 20 minutes, so if you are willing to take a break, you don't need to try to carry bulky extras, the main disadvantage to the PC vests (aside from the EXTREMELY COLD NIPPLE SYNDROME for the first half hour), but even one set takes up an awful lot of luggage room if you are traveling.


Thus the evap vest is more long distance-friendly, but less efficacious in humid climates. I personally don't like the feel of the evap vest, clammy, despite the fact that the one I have doesn't really get me wet.


Both vests are a bit heavy, by the way, but that's only a minor distraction.


EDIT: the PC vest use described above helped immensely, as does the evap vest in a dry environment, but neither is an air conditioner; expect them to make a really hot ride tolerable, but not wonderfully comfortable.

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I have the evaporative cooling vest. The Houston area is certainly humid and hot.

1: It works in high humidity. I have a mesh jacket and ride a RT so I do not get "maximum" airflow.

2:They are clammy feeling only when you first put them on. If you use a cotton t-shirt it will get it moist. I much prefer a tight fitting UnderArmour shirt.

3: Very easy to recharge. I simply buy a bottle of water and pour it in the plastic bag the vest came in. In a few minutes it is ready to go and once you get the feel of how much water to put in there are no "drips" when you put it on.

4:It seems to cool very effectively for about 1 1/2 hours.

5:I don't find them worth the effort for my 50 minute ride to work.


To really see how effective they are ride with one for about a half hour then stop and take it off. Ride a little while in the same heat without it. While they are not air conditioning they do keep your core temps enough lower that you will not sweat near as much and you remain MUCH more comfortable and alert.

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I'm in a part of the US that's both hot AND humid (South Carolina). I picked up a couple of evap vests, (one for me, one for her), from a vendor at this year's BMW RA rally from Silver Eagle Outfitters . They were a bit pricey, but it was so hot, ...I was just glad they only cost what they did.

Do they work?

- Yes, mine/ours work very well even behind fairings and a large aftermarket windscreen, which means they'd probably work even better on a more open bike.

Do they get your clothes wet?

- Mine does because I don't take the time to wring it out as per the instructions.

Is that a problem?

- Not if it's hot enough to be wearing a cooling vest.


Pretty easy and simple, stuff it in a small plastic bag, pour in a bottle of water, give it about three minutes to soak it up and ahhhhhhhhhh. Lasts about two hours of riding, no good unless you've got a good mesh jacket. (Or no jacket).

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