QUESTION: I’m in my early 40s, race, and do most of my structured training indoors using a KICKR BIKE and TrainerRoad. It’s efficient and I like being able to nail my intervals without worrying about cars, stoplights, or weather. But here’s the problem: my indoor FTP feels way harder than it should. I’ve got a power meter on my outdoor bike and wear a heart rate monitor for both, so I know I’m putting out more watts outdoors, and it feels easier. Indoors, I’m blowing up at numbers that I can ride steadily outside. What gives? – Uwe M
RBR REPLIES: You’re not alone — this is one of the most common complaints among riders who train indoors, even with top-of-the-line setups. And the usual suspect? Poor cooling.
Outdoors, you’re riding through a constant breeze, even on calm days. Indoors, unless you’re blasting yourself with serious airflow, your body can’t cool itself efficiently. As your core temperature rises, your heart rate climbs and your perceived exertion shoots through the roof — even if your power doesn’t. That’s why your indoor FTP feels like a struggle while your outdoor numbers feel smooth.
I use a KICKR BIKE too. The fix for me was threefold: turn the thermostat way down, run a high-powered fan in front (I use the Wahoo Headwind), and add a second, cheaper fan from the side, aimed at my torso. The key spec to look for is CFM — cubic feet per minute — which measures how much air a fan can move. Even regular fans with high CFM ratings (like some $40-60 box or blower fans) can sometimes move way more air than sleek, cycling-branded ones, and can make all the difference during hard intervals. At the very least, make sure that your main fan in front has the capacity to move a lot of air.
Other small things can factor in too — like constantly pedaling without ever coasting like you naturally do outdoors, slight fit differences, or how your trainer simulates resistance. But nine times out of ten, cooling is the culprit. Fix your airflow, and your indoor FTP might just start behaving itself.