I mentioned to a friend that I just got a trainer to use during the winter and he said I should make sure I use at least one fan. He said he remembers being told or reading (he used to be a fairly serious racer) that having a fan blow on you is important for more than just comfort, and more than just that not dripping with sweat lets you work harder. He couldn't remember any details.
Any idea what he was talking about?

I mentioned to a friend that I just got a trainer to use during the winter and he said I should make sure I use at least one fan. He said he remembers being told or reading (he used to be a fairly serious racer) that having a fan blow on you is important for more than just comfort, and more than just that not dripping with sweat lets you work harder. He couldn't remember any details.
Any idea what he was talking about?

You definitely want at least one good fan pointed at you while on the trainer. You'll overheat and sweat like crazy without one, I made that mistake last year and now I never start a trainer session without the fan going.

You will seriously overheat without one- falling off the trainer with heatstroke is no fun. This isn't even mentioning that it's also simulating what you get in the real world. Get a good floor fan, about 18" in diameter, and this time of year they aren't everywhere, but you'll get a good price when you find one. Even with one you'll probably need a sweat drip guard for the bike- either one of the pre-made variety, or something you set up yourself.

i think that it is fital to have a fan set up whilst on the trainer. i purchased a trianer 2 years ago for the winter season and within the first week without a fan i had to be taken to hospital with a bad case of heatstroke and it is not fun. the number one thing to do on trainers is cool youself down and along with a drink fan is number one. don't risk it set up a desent size fan pointed on you to cool you down.

Fans are important: I have my fiancee cheer me on during intervals.

This time of year? I just open the sliding glass door a bit. 20 degree air cools one most wonderfully. A fan probably is a better idea.

Short story to reinforce the importance of a fan:

I live in the Northeast, so the past 10 weeks of training have been almost exclusively on the trainer. I relocated 400 miles south about 3 weeks ago and did not have much room in my car and did not bring my fan with me.

My last 3 weeks of training have gone like this:
1) warm-up for 15-20 minutes
2) ramp up to do my interval, then start the timer
3) about 5 minute in, my power output drops like a rock
4) proceed to profusely sweat and towel off
5) continue sweating and struggle to keep the target heart rate

Example: yesterday's ride, warm-up, then a 60 minute interval at 150-160 BPM with cadence above 100 RPM. My power output went from 300+/- 25 watts, then quickly dropped down, and leveled out around 185 watts.

I am going to buy a fan today.

Does anyone know if the body would eventually adapt to this?

Could this possibly be a good training tool for racing in much hotter climates that one is not accustomed to?

It does take some time for the body to acclimate, but it definitely will adapt.

I know people who would ride the trainer with a skinsuit and no fan for up to an hour or two, just getting ready for some of the hotter (105 degree) SuperWeek races. This was after a few years ago when there was a 110 degree race and the only people who finished were from california/southwest area. Nearly everyone from a cooler climate had to drop out.

I never use a fan, and I am in upstate NY, where I will need to be on the trainer 2-5 hours a week for a few months. I am a heavy sweater that has trouble with cramping in hot races. I always figured I should train in the kind of enviroment I am challenged by, and hopefully I will slowly adapt. On a trainer, it's about the work not the performance, right?

A friend explained it to me like this...you want your heart rate up because of working hard, not because your body temperature is too high..

with a fan I have to work twice as hard to get a 145 average over an hour

Lots of confusion here.

Heat acclimation takes only 10 days or so and goes away as fast. Do a search on the topic for more detailed info,

As far as actual training, you want to do whatever lets your muscles work the hardest. If you can sustain 300 watts in optimum conditions, why would you want to overheat and limit your power output to 250 watts. That wouldn't be stressing the muscles.

In a sense you could compare this to sleeping high and training low. Sleeping at high altitude provides a physiological benefit, but you want to train at low altitude which provides more oxygen and lets your muscles work harder (higher wattage).

We've all seen people riding in those "sauna suits". How much sense does that make?

About as much as riding the trainer without a fan.

Definitely use a fan. 2 is even better. And hydrate like crazy. I go through 2 bottles in an hour on the trainer.

It does take some time for the body to acclimate, but it definitely will adapt.

I know people who would ride the trainer with a skinsuit and no fan for up to an hour or two, just getting ready for some of the hotter (105 degree) SuperWeek races. This was after a few years ago when there was a 110 degree race and the only people who finished were from california/southwest area. Nearly everyone from a cooler climate had to drop out.

Ughh! Had to be Bensenville, but then the rest were all really hot (especially that first week)

I use two fans, a box fan on the floor to keep the lower half cool, and one of those on an adjustable mast that pretty much blows into my face and chest. It's the only time when wind isn't a liability. I get the heebie-jeebies when I start feeling heat pooling around me that isn't normal for a stationary activity.

I have to say, I am using my trainer mostly for sst training, and the occasional recovery spin. As hard as it is now to maintain an 80-85% of MAXHR pace for :30+ min., It would be nearly impossible with a fan. I don't know that my legs could take the extra intensity. Of course, I tested for my HR without a fan so...

Been on my trainer a couple of times now using one of the Spinervals DVDs. I am surprised how much more I can hurt on it than on a Lifecycle at the gym. Not sure if it is because of the DVD or because there is nobody (and by "nobody" I mean women) to see me sweating and gasping. Either way, I hope I can keep to a regular schedule over the course of the winter.

Also, Pablo, if your fiancee actually cheers you on you better marry her. My wife bought me my bike, but has no interest in riding herself or watching me ride.

I think the general consensus was summed up by TouchOGray, you want to get your heart rate by working hard not overheating. That is probably what my friend was getting at.

I bought a spinning bike for my home gym last December and don't ask me how I survived the winter months with no fan (and the furnace going) all that time.

This time around I thought I could get away without using a fan, but during my first few weeks without I was sweating so much (using the CTS train right videos) I'd leave a pool of sweat around my bike (and on it). I hated being completely soaked when I got off the bike, not to mention I spent a huge amount of time wiping my face. Top that off with several sessions where I was so hot I thought I'd pass out....

That was enough for me to buy a fan, but not just any fan.

I did some research and found a fan with 3 airflow settings (mild, strong, off/on strong) and another for rotating 180 degrees. It's whipser quiet and comes with a remote so I never have to interrupt my session.

I can now wear a t-shirt (before I had to wear a tank top), I don't feel like I'm going to suffocate from heat, I can see without sweat dripping infront of my eyes and my bike and floor aren't covered in sweat anymore. I sweat maybe 1/2 to 1/3rd as much as I used to and it's great to be able to breath freely while standing on the pedals...:D