See the below thread showing everyone saying how important cooling is and how it affects their power output and heart rate. Your heart rate rises both to supply oxygen to muscles but also to cool your organs and brain. Cool your core (torso) better and you will perform better, indoors or out. Outside the cooling happens whether you want it or not. Inside, you have to make it happen. And any fan built into the trainer is not enough to match outside.
The difference in power between the spin bike and other bikes has been taken from a Garmin Edge 530, a Windows 10 PC running Zwift, an iPhone running the Rouvy App, and an iPhone running RideWithGPS. I’ve also changed from Bluetooth to ANT+. In each case they all report the same consistent power data with the spin bike being about 80 - 100 watts less at the same HR. It is very odd.
Oh, I’m with you 100%, cooling helps a ton, but cooling doesn’t even enter into the equation here. Let me explain. I really don’t need these 1-hour rides to prove to myself something is wrong with the power meter pedals when they are on the spin bike. This is because the wattage feels significantly different within the first 30 seconds of the ride. Cooling doesn’t even have a chance to offer a benefit.
If I jump on the spin bike and dial it up to 200 watts immediately, I’ve got about maybe 3 - 5 minutes that I can hold it before having to back it off. If I jump on my recumbent or my Son’s MTB and immediately push it to 200 watts, I can hold it all day.
As you can see, the difference isn’t gradual at all. The spin bike is simply much more difficult at 100, 150, 200 watts, etc. when compared to other bikes outdoors. I’m at a loss what to attribute it to.
If the difference is truly there in the first 30 seconds when starting from resting heart rate, and you have data telling you that, then I agree is unlikely to be cooling.
But your comments keep mentioning 200 watts and 5 minutes, which if that is anywhere near threshold, is plenty of time for cooling to be a major factor.
I know, it is only confusing because it is. Trust me, no one is more confused than me.
I know it is hard for anyone to really get a feel for what I’m seeing and feeling without being on the bike, but yes, I can feel the difference right away. Simply put, 200 watts on the spin bike just doesn’t feel anywhere near the same as it does on other bikes and I don’t know why.