I was wondering if anyone has seen data on the impact of ambient temperature on performance. Yesterday at 80 degrees F, I rode a run on Rouvy that I've ridden 4 times before. It was a fast 7 mile 5 degree max flat run that works well when I've already worked out hard on outdoor work. My time was 2 seconds off of the same course in April when it was really quite cold here still. House was probably 65 degrees F at that time and probably somewhere above the outdoor temps yesterday (though I didn't look at the thermometer inside, just was saying it's nearly time to run the AC). Since I had two data captures so close, I decided to compare them. My heartrate was much higher yesterday and the training load was 3 times what it was in April. I don't recall the "feeling" from a ride that far back, but usually when I'm working out, it feels hard and I didn't feel much different yesterday.

I can attribute part of the difference to having just cut a couple acres grass on foot (hilly so lots of pulling the mower around) and dragging branches in the hot weather. But still, 3 times the training load seems crazy to me for the same MPH and time. Does heat make that much difference in the output required when riding? It would be interesting to know when comparing data. Like if it's overly significant, it would be silly to try to beat one's own time on a hot day.

The figures don't suggest I was in that much better form in April even though I was still real roads once a day and thus finishing more miles per day.

Your body has a lot more work to do keeping cool. Fuel and hydration, electrolytes get depleted quickly. IMO, 80 degrees is not that bad, certainly not extreme, but if your body is not used to it, it takes a toll.

That makes sense though I had hydrated all day. In Western Washington, one never gets used to having high temperatures, it's often gray, cold and miserable and seems to be getting worse over the years (or as I get older, I notice it more). 75F is hot here. August will have 3 or 4 weeks of much higher temperatures but it's fleeting to have extended periods of good weather. I know why I live here, but it's not for the weather. Long way to say, I'm not used to it, dragging tree limbs in the sun yesterday was murder. Maybe that's all it is.

My concern is that I'm destroying my fitness by doing all my riding inside for the last 3 months. Honestly the indoor riding seems a lot harder (there is no such thing as coasting down the hill on my trainer, it still generates serious resistance), but feeling is not a necessarily a valid indicator. If there is a variable in temperature that's pronounced, that's good information.

Don't make the mistake of thinking it's just temperature. Other things can factor in too. Sometimes on a ride where I've been off the bike for a week, I'll have some of my better performances on certain climbs I look at. So when comparing metrics of two rides, try to make sure your days prior had similar times on and off the bike.

Personally, on rides where I can stay at 16 mph or better for most of the ride, then temperature doesn't come into play much because even in the mid 90's 16 mph of air flowing past me provides plenty of cooling. It's only when I stop or go slow that I feel the heat.

Unfortunately there is no wind in the house though I see they have fans now that simulate the riding wind.

I'm bringing up the AC today and will try riding the same run again with the house cooled off.

If you are on a trainer without fans I'm not sure how you stand it, especially this time of year. I sweat enough with two powerful fans but at least they keep it bearable.

I'd also look at way more than 2 data points before jumping to any conclusions.

It's not just temperature. 90F with 0% humidity is way different than 90F with 90% humidity. Wind and shading also make a huge difference.

I am starting to realize that. I'm looking at the Wahoo product though I swore I'd not buy any more of their products after poor support on my Roam due to having a different brand trainer. But maybe I should go the other way and get a Kickr, fan and play their game. The fan does look pretty impressive and kickr is probably much quieter than my Saris.

I didn't check the humidity, I do remember the wall of misery that would hit when the plane door would open in Virginia on work trips, always a instant drain of all energy. Humidity shouldn't be that bad here right now though.

Missed that part about "house". <grin>

Cooling your house won't do as much as having a air circulating past you at a reasonable rate. IMO. A decent box fan should do the job.

Here is a view of time vs temp on a fixed commuting route I rode in both directions every day for years and years. The dataset represents 5 years of M-F commuting by recumbent, about 1500 data points so 750 different days - I travel alot for work thus nowhere near 250 days per year for those getting out their calculators. I stopped 3 years ago when the local workforce shrank enough they closed the building and I started working from home. I still ride everyday but just an hour at mid-day. There is no correction for headwind, but for sure a lot of the width of the variation on any given duration is wind. Traffic not so much as it was rush hour every time and generally the same traffic. I think the real knee of the curve is more like 55 degrees F but the basic curve fitting in Excel isn't rational where you can get a sharp break and I'm two lazy to split the data and splice together two pictures, etc. The datapoints are very approximate, no stopwatch or ride data app, just checking the time at both ends. Same for temps. But, I thought it was interesting in an overall sense once I had enough data points.

You will always have a performance impact while riding on the trainer compared to outside. Even with a decent fan, it's a problem shedding heat. Most competitive riders I know who ride the trainer during the winter track a separate FTP and LTHR on the trainer because it's not useful to try to use outdoor numbers.

Oh man, just go down to the local hardware store and buy two 24" (or larger) box fans. Turn them up high enough that you need to wear glasses, just like outside. Fix you right up. I wouldn't turn up the AC. Even though heat cuts performance now, riding in hot conditions will improve performance over a couple week period, not only in the heat, but in cooler conditions also. I don't wear a shirt or jersey indoors.

I think temperature is really more individual in how it effects a person. I have Raynaud's Syndrome and get cold pretty easy. I love the heat and tend to ride much faster when it is warmer. Normally I ride very early in the morning so not high sun but dew point can be pretty high in Illinois is summer. I find the colder it is the slower I start and I never get quite as fast. Sometimes I run 2-4 miles before and jump on bike that helps even more.

I am probably the only person who easily can ride my trainer full out for 95 minutes in the basement with no fan at all on. I don't even take a drink. There is a pool of sweat under the bike but frankly I think temp as I say depends on person. I might add the opposite too I do ride even in winter outside when it is cold as long a not real windy. My feet just go numb.