Originally Posted by
Barry2
LOL only 3%, I wish it was only 3%
I run a power meter on the bike... I'm NOT guessing !
For every Watt your body places into the bike as power, your body wastes 3.2 Watts as heat. We are not a very efficient engine.
This heat must be cooled or we overheat.
We are AIR cooled and once the ambient rises, the cooling effect drops.
The body will reduce the power output rather than overheat, and the time on the route goes up.
So, ambient temp very much controls your ability to output power and your speed.
This doesn't take into consideration dehydration, which just makes matters worse.
Barry
BTW I'm in California, last week it hit 107F / 41.7C
Body Temp = 98.6F / 37C.
Can you imagine the "cooling" effect of air that is 8F / 5C hotter than you are!
I run power meters too. Are you saying in hotter weather your segment time increases by 30 percent or are you saying your power drops by 30 percent?
It gets hot where I am too, but I try not to ride when it gets over 100F. When I do, my power doesn't drop by 30 percent. Even if it did, according to bikecalculator.com, my segment time on a 30 mile ride would increase in time by only about 18 percent.
That all being said, now I'm wondering what my power drop is when it gets around 100F. I need to break out VeloViewer. Over 30 miles, it would unquestionably drop at that temperature, because I really dislike the heat. My gut feel would be around 15 percent. That would drop my time by maybe 10 percent. And I'm a big guy who hates the heat.