Howdy all,
I just recently picked up a power tap, and was wondering what differences people observe between wattages (say 30 min threshold test) with and without a fan. Also, I’m curious about the same measurements comparing the wattages of indoor (w/or w/o a fan) and outdoor riding. Evaporative cooling is a beautiful thing, and I’m thinking of getting a fan for when the weather will go to crap and I’m driven indoors here in New England.
you need a fan.
the power difference will vary greatly depending on your room, ac, and power output.
a 200 watt rider will be putting out 660 watts of heat
a 300 watt rider will be putting out 1000 watts
so the cooling challenge goes up as you get stronger. but you really need a fan or it will get stupid hot.
I’ve never “tested” with or without a fan so I can’t speak to that.
Outdoors vs indoors will vary from individual to individual but my FTP is about 7% higher outdoors (it’s not quite 10 but more than 5 so I use 7). I also find my cadence in the same gear and same power to be about 5% higher outdoors vs indoors.
It sucks…I do most of my riding indoors though. I have one fan (wish I had another) and just work off what my “indoor” FTP is. When I ride outdoors, it’s way easier to hold the wattage.
I wouldn’t even try to ride without a fan. I’m only on the trainer when it’s under 30F and/or snowing here in Ohio. I always have at least 1 window open and a fan in the window. So I’m getting the evaporative effect of colder air.
I still sweat loads…although I put out a fair number of watts 
I’ve done 2 hour rides in rooms with other riders that weren’t nearly as cool, and my watts were at least 10% lower. I ride the same watts indoors and out. Even though I don’t watch it, my hr ends up being about the same too.
-Physiojoe
You’ll spring for a >$800 PT hub, but you’re “thinking about” getting a simple $20 box fan? Dude … go buy 3 fans. Your body will thank you.
I do a lot of riding indoors. The best thing you can do is get a powerful fan, and point it right at your face. A “30 minute threshold test” without a fan would be near impossible for me. I’d wager at least 20% less wattage if I could suffer through it.
With two large box fans my FTP is a little more than 5% lower than outside.
I can’t even take it without a fan, but I’d expect that it would be at least 10% lower, probably more.
Howdy all,
I just recently picked up a power tap, and was wondering what differences people observe between wattages (say 30 min threshold test) with and without a fan. Also, I’m curious about the same measurements comparing the wattages of indoor (w/or w/o a fan) and outdoor riding. Evaporative cooling is a beautiful thing, and I’m thinking of getting a fan for when the weather will go to crap and I’m driven indoors here in New England.
enjoy
Howdy all,
I just recently picked up a power tap, and was wondering what differences people observe between wattages (say 30 min threshold test) with and without a fan. Also, I’m curious about the same measurements comparing the wattages of indoor (w/or w/o a fan) and outdoor riding. Evaporative cooling is a beautiful thing, and I’m thinking of getting a fan for when the weather will go to crap and I’m driven indoors here in New England.
I have been using a CycleOps 300PT trainer for a couple of years with a small oscillating fan that I position so that it blows on my back since I seem to get the most benefit from that direction. Recently, I bought a fan at the local Home Depot for $60 that sits on the floor in front of me and blows like a hurricane on my front side in addition to the rotary fan still blowing on my back. Both are angled about 20-30 degrees so they aren’t blowing at each other. I am pretty sure I can do 5% higher watts simply after adding the second, big fan. Might be more, but it’s hard to tell since I have picked up some fitness along the way too. Even with the additional fan, I put out more watts on the street on my road bike than on the trainer. Probably another 5%.
It’s definitely worth the investment because your body has to redirect blood flow away from your working muscles to your skin in order to get your body cooled down. That means you don’t get as good a quality workout.
FWIW,
Greg
I do a lot of riding indoors. The best thing you can do is get a powerful fan, and point it right at your face. A “30 minute threshold test” without a fan would be near impossible for me. I’d wager at least 20% less wattage if I could suffer through it.
x2. If you’re not using a fan, you’re getting an inferior workout.
Look up “Lasko Wind Machine” in any search engine.
I got mine at Meijer for about $28
Thank me later 
jaretj
I’ve never experimented riding the trainer without a fan. I don’t know why you would. I use a Lasko 24" vortex fan and it seems to get the job done. If I really feel warm I have a 5000 cfm work fan that is like a mini hurricane, but it’s almost too much wind and it’s really loud. My indoor and outdoor wattages are the same for seated efforts. Out of the saddle, hard efforts are not the same indoor vs outdoor due to the bike being fixed on the trainer. I can’t even come close to hitting the same sprint wattages indoors vs outdoors.
Point many fans toward you during efforts. I especially like one from behind.
Absolutely get a fan. I recently got an 18" Air King that puts out a
pretty good volume of air. Definitely makes a difference.
You’ll see lots of different reports about peoples indoor and outdoor
wattage. I find that for me it is largely a matter of attention. Outdoor
I don’t need to pay much attention to hit a pretty good % of my FTP
during a ride. I just ride. Indoor, if I’m not staring at my watts, I seem
to let up a bit without meaning to. I’ve managed pretty good 20
minute test numbers indoor though if I stare at the watt output the
whole time.
Get the Air King with a stand. It feels like the Spruce Goose is taking off in front of you.
I’m about to pull the trigger on one of these:
Looks beastly…