Found a little on this topic in searching the forum, but can’t quite find a direct conversation on this:
I’m fairly new to TR, and I’m finding that I am reaching exhaustion at slightly lower heart rate levels indoors on the trainer than when I’m riding outdoors. I ride with a ceiling can on high and a 16" box fan blowing on me. In a bike race my HR reaches around 175, but when I’m indoors on the trainer, I feel like I’m about to blow up around 168 or so.
I can’t tell if this is equipment/cooling related or if I just need to toughen up and push through that fatigued sensation.
Medium size blower fan (gray and yellow), mounted over my primary screen. it is pointed at my chin and upper chest when on the hoods. It now has a ducting box to pull air directly from the open window, which is nice and cool in winter. I can turn it on via remote and adjust flow with an extension on the switch.
Large size blower fan (black and gray), mounted on a desk to my left. It is pointed at my middle and lower chest when on the hoods. It now has ducted vent hose to pull air directly from the open window, as above. I can reasch the switch from the bike.
18" Circular floor stand fan (black and just out of view in the pic), placed towards my left rear. It is pointed at my lower back, booty and upper leg. It has a remote and the ability to oscillate as well as 4 speeds. I sometimes use the motion to stir the air in the room.
With this setup, I have hit high power and HR numbers together and been able to keep from overheating. Point being that if you want to maximize your indoor training, take the cooling aspect as seriously as any other part of your training and prep.
Indoor HR about 5 or 6 beats lower than outside but that’s due to hills and wind Etc. 183 was my max inside until last ramp test where I hit 187 at the end but I nearly had a heart attack, it was brutal.
Chad, you’re setup is super legit (minus the saddle bag on that Ruby). I definitely have Pain Cave jealousy right now. I’ll be getting on to Amazon this evening to order some additional fans.
Also, I’m glad to hear that this could very well be the issue and it’s not just that I’m a pansy and I need to work harder.
Brushman, I just stumbled across the notion of marrying up the indoor/outdoor power/endurance/HR numbers in my search of this forum, so I’ll have to crunch some numbers and get back to you. Thanks for the suggestion.
I should probably remove it, but it’s the wife’s only bike. I have all of the actual bikes to ride setup with individual bags so I never have to swap them (in effort to prevent the inevitable day I forget to put one on and get stranded )
I think too much cooling is likely not a problem for most people. I have had an issue with extremely cold air from the window blowing on me from too much fan speed, and getting chilled. But that was on my for not adjusting to the conditions. If at all possible, I’d like to be a bit cold inside rather than too hot.
Thanks. The only problem I’ve had is the fan drying out the contacts on my HRM before I’m warm, but since switching from Garmin to Wahoo I have not yet had that problem.
I’ll try to cool things down and see if that helps me achieve HR closer to my outdoor levels, taking into account the other factors mentioned by forum members above.
PS, I do the same thing with regards to tube/CO2/tools on each of my bikes so I never have to think about it.
During the winter in my drafty Michigan basement I can get the temperature down to 55F with low humidity. With a big fan I can push myself harder on the trainer than outdoors because I don’t need to balance my bike! I have actually crashed in a cold MTB race because I dug too deep on a climb and sorta blacked out as I crested the hill. However in May when its warm and humid in the basement I cannot work nearly as hard. Things improve in the summer because the A/C does a good job of reducing humidity. I have bought a big dehumidifier which I hope will help in the spring/fall when neither the furnace or AC is needed much. I think humidity is a big factor for everyone to monitor as well.
I will counter that I don’t think it has to do with cooling, as a lower HR would suggest that you are cooler than outside since your body isn’t diverting blood flow and energy to sweating. This is why we will usually have a higher HR for the same efforts in higher heat environments, since you are getting less blood flow to your muscles. I think there’s a lot to be said about the steady controlled effort inside keeping your HR lower. When climbing outside, you will tend to grip the bars tighter and to do several other things that might tick up your HR.
I should probably remove it, but it’s the wife’s only bike. I have all of the actual bikes to ride setup with individual bags so I never have to swap them (in effort to prevent the inevitable day I forget to put one on and get stranded 
)