Etter å ha tenkt litt til, fant jeg ut at det kanskje ikke var så feil som jeg først antok. Man må nok bare passe på at utslagene i jojo-syklingen ikke blir for store.
Etterhvert fant jeg denne, som viser at Joe Friel også er usikker. Men han har i hvert fall et par mulige forklaringer, som til sammen kan utgjøre forskjellen man opplever. Bedre ventilasjon, mulighet til mikropauser/variasjon, muligheten til å "bruke" sykkelen i bevegelsene osv er blant alternativene. Han tror altså ikke at det er 1 grunn, men at det antakeligvis er en kombinasjon av flere faktorer.
MY ANSWER: This is a common question every winter. A lot of riders experience this. But I’ve also heard from some who have exactly the opposite problem—better numbers indoors than out. So it remains a mystery. There are a couple of possibilities that may explain it, but they are rather lame I’ll have to admit. (I'm assuming the same power meter and bike were used on both tests.
One is that when riding on the road there are brief episodes of “recovery” due to slight hills, cornering and changes in wind direction. These little changes don’t occur indoors on a trainer where power is usually much steadier. Some research shows that these little “mini-recoveries” allow the rider to go harder overall. In fact, I’m told that when going for an hour record on the track they sometimes train to be “unsteady” in power output order to take advantage of this little oddity.
The next is that when riding on the road the bike actually rocks from side to side slightly while the body remains relatively steady over it. On the trainer it’s the opposite – the bike is locked in place so the rider’s body moves slightly side to side while pedaling. This requires a somewhat different technique and muscle recruitment and so may elevate HR and effort “artificially.”
It sounds like you have already eliminated the third one – that heat build-up elevates HR when riding indoors more so than when on the road. Lots of fans help here.
I’d also be interested in seeing if the rider paced the two TTs the same way. In other words, did he negative or positive split the two trials in the same manner? Someone may be more adapted to riding on the road than the trainer and be much more unsure of how to pace themselves indoors. Or the other way around.
Could one of these explain a 7% difference? Probably not. Could some combination of them account for that? Possibly.
Bottom line is that I really don’t know.
