Did a duathlon today that used the same course as our late spring local sprint tri. Hoping to better my bike time, but was slightly slower.
There are dozens of factors (running first, roads are worse, wind, being a sissy, etc) but another racer thought the temperature might play a role. Probably 20 degrees cooler today than in June. He is a pilot and said they factor air temp into runway needs, etc.
A quick google turned up an article in Velonews by a Zinn which mentioned that and several other factors. Is this common knowledge? Would 20 degrees make a noticeable difference?
I have noticed the same. Chemistry tells us that air is more dense at cooler temperatures which would increase resistance. This may or may not be a measurable factor.
Could be especially at multisport pace. Air is more dense but sometimes you can make more power too and it about cancels out. Could also just be the direction of the wind or other things
When I ride in the winter, my average speeds are always a lot slower.
This also could be due to being less fit (in my example); but maybe the cold temps make the rubber in the tires harder, increasing RR?
In addition to the air being denser.
Even roll-downs that I normally average a given speed in warmer weather, are always slower when it’s cold out.
I had a very similar experience this weekend as well. I had a higher power output but my average speed was low and my time was longer than other races of the same distance. It was 7C (44F) during the bike leg and wet to add insult to injury. I have been scratching my head as to why I was 9 minutes slower than I had anticipated and this could be an explanation.
Doesn’t this depend on whether your body can handle racing better in heat or cold? Personally, I race ride faster in colder weather…I prefer 40s, 50s, and 60s, vs. 70, 80, or 90s.
Could be especially at multisport pace. Air is more dense but sometimes you can make more power too and it about cancels out. Could also just be the direction of the wind or other things
Doesn’t this depend on whether your body can handle racing better in heat or cold? Personally, I race ride faster in colder weather…I prefer 40s, 50s, and 60s, vs. 70, 80, or 90s.
Yes, people will be affected by heat differently. Could depend on race pace too. If you are up near threshold (oly pace) and really powerful (due to talent or size) heat is more likely to limit you than ironman pace or someone smaller.
I tend to make more power in the cold but speed doesn’t change. I cancel out!
Temperature affects air density, which affects drag. The colder, the more drag. You can find charts for density of air vs temperature to find out how much. it’s not much, perhaps a 4-5% difference in the density value, so if you apply that linearly you should have 4-5% more drag. Same goes for air pressure, which will affect air density. this is one of the reasons why specific locations, dates and times are chosen for things like land speed record/hour record attempts.
All else being equal, you will bike faster on a hot day than on a cold day. but of course other factors, like body acclimitisation also play a big part. Too hot and your body suffers.
What Jack said, can potentially push a bit more power (than a really hot day but not much more than a mild day) but the air is more dense. More likely culprit is combo of air density, worse roads and specific wind conditions.
What Jack said, can potentially push a bit more power (than a really hot day but not much more than a mild day) but the air is more dense. More likely culprit is combo of air density, worse roads and specific wind conditions.
This calculator has an entry for temperature as one of the variables. A quick hypothetical for me gives a .2 mph slower speed at 250 watts when the temp drops from 70 to 50. And I assume that does not take into account any extra clothing one might be wearing.
