10/18/24 9:53 AM

I want to get people's input on the effects of temperature on ride speed. I have some "standard rides" where I pretty much know how long they should take. If I get home sooner, I've had a good day and if I get home later I think about the wind, the heat, and how I felt.

With cold weather now dominating, I've been thinking about how much slower these rides are. I can calculate the effect of temperature (air density) on speed and that works out to 0.1 mph slower for every 5 degrees colder. But my ride times are double that slower when it's in the low 50s vs. the low 70s. A ride that should be 10 minutes slower due to higher air density is 20 minutes slower instead. Why? My wife suggests "stiff joints" but I don't feel that.

Any thoughts?

10/18/24 10:08 AM

Are you adjusting psi for lower temps? For that matter tried different psi in each time/temps to see if makes a difference, being so minute...

10/19/24 2:46 PM

At cooler temperatures, doesn't the body expend some energy to maintain body temperature? Granted, 50F is not exactly frigid.

Even at the same temperature, my times vary more than yours, some days I just feel like riding harder than others (and I seldom ride at the limit).

10/19/24 4:21 PM

I frequently noticed that when I'm riding at temps between say 45 and 55, that my sinuses tend to "run" alot more than at warmer temperatures. Could Your breathing and gas exchange efficiency possibly be impaired somewhat at the lower temps?

10/20/24 5:52 AM

Temperature effect on tire pressure: 25 degrees F colder would drop tire pressure by about 5%. Any change in rolling resistance would be lost in the noise.

You hear about colder temperatures requiring more energy, but it seems to me that as long as you are sweating, your body is producing more energy than it needs to keep warm. The excess is dissipated by sweating.

As far as steady effort between rides, some of my riding buddies have called me "the metronome."

With the higher density of air at colder temps, you would think that O2 exchange would be improved. Then again, your lungs have to heat up the air. I wonder if XC skiing coaches have thoughts about race performance at different temperatures?

10/22/24 7:04 AM

OK, I rode the same 12 mile loop this morning, avg temp 43F, that I rode a couple days ago, avg temp 61F.

Compared to the hotter ride, my avg speed this morning was .8 mph less, avg and max hr both 7 bpm less, and avg cadence 3 rpm less.

Wasn't trying to ride particularly hard either day, possibly a little softer this am.

Just the facts, no interpretation offered :)

10/22/24 3:17 PM

My time comparisons are over longer rides (4 to 7 hours) so I get a little more precision in the measurements. I had a further thought about the psychology of riding in the cold. Maybe it is just easier to back off without realizing it? That said, I feel just as tired, if not more so from these cold rides. Today's ride started cold (50 F) but warmed to around 70 after the first 4-hour leg. The second leg was just as fast as it normally is in warm weather. The first leg was maybe 7 minutes longer than "normal.