Jrasero

About the same but depends on the weather. I thought about it the other day when if was 38 degrees here in NY. I think it depends on how cold it is and thus how much you are wearing but also cold air is denser. Someone once told me golf balls fly 20% shorter in the winter due to the denser air, thus it would surprise me if you are losing 20% to even 25% of your performance during the winter unless you have kept your summer training regiment up bigtime or you simply put out massive watts regardless.

rsbob 

that would be an interesting comparison if one could do a control for wind, compare watts at a constant speed on the same course summer vs winter.

Koyote

Umm, most of the good online calculators allow all that and more. Example.

Troul 

place the indoor trainer outdoor, it might give a ballpark measurement.

rsbob 

Oh man, I don’t want to drive all the way to a ballpark.

msalvetti

Interesting topic, I thought it was only me. My rides are always around 20 miles, but in those miles there are probably at least 40 road crossings. My average on days where I can wear shorts is about 14 mph, meaning I usually get up to 16-18 mph between road crossings.

I will ride if temps are above 20F and it's not too windy. I am probably 1-2 mph slower when I'm dressed for winter. Since I always ride the same route, ETA is where I see myself slow down. In warm weather I get to the halfway point in about 40 minutes. When it's cold, probably more like 42-43 minutes.

Mark

CanNik

Seriously I see NO fun/enjoyment whatsoever in this need for knowing the finest details of a ride, mph, etc, almost obsessive, what next, how does your speed change after a pee, a coffee, a cake, calorie intake !!!!!!!!!!, warm as compared to cold tarmac roads, the list is endless

Troul 

cant just say coffee, cake, without knowing the brands, was it on sale, from which store & during what hour of the day was it bought...

Groasters

Scotland: 2mph difference roughly, hilly terrain (70-80ft/mile elevation gain), due to weight/aero/rolling resistance/cold temps.

Summer, 15-25 degC: lightweight bike, race fit clothing, GP5000 tyres
Winter 2-10 degC: full mudguard (fender) bike, winter clothing, Gator Hardshell tyres.

If I rode an aero bike in summer (I don't) the difference would be larger I think.

It's quite interesting riding with a power meter summer/winter. For the same average/normalised power, average speed is reduced due to the above factors but so is heart rate increased a little bit, I've noticed.

Groasters

Cyclists? Obsessive? How DARE you make such accusations, and in bold text too!

Troul 

IKR!? Some bold nerve!

rsbob 

If you don’t want to read a thread, then it’s better to move on rather than lecturing and getting all negative about it. Welcome to the BF.

Jughed

Air density = .5-1 mph.
changing from GP's to Armadillo's = .5-1 mph
Cloths have some negative effect.

And I find that I can't spin out the RPMS with cold legs... I find myself grinding all the time.

Jughed

I probably fixed it for you...

SoSmellyAir

We are not turbos and it is not all about air density. But the milder winter temperatures here in SoCal makes sweating more efficient and riding uphill less strenuous.

jadmt

so I went out or a 40 miler and it was 29°F and slight cross wind. I rode pretty easy for 3 or so miles to try and warm up and then I did the next 17 miles riding a decent effort. I was just under 20mph at the turn around. the next 20 I definitely felt like I need way more effort to try and keep above 19mph and by 30 miles I decided to just ride where I was comfortable and the ride ended with a 17.8 mph average speed. It was still 29° at the finish. Probably about as long of ride at that temp as I will do unless I get better toe warmers...Also my water was too cold to drink so need an insulated water bottle. I really can't complain as this late in November in Montana is not usually riding outside weather.

Mtracer

I have no idea how much slower I am. But I'm slower. Mostly because I can't put out the same power. I'm not sure if it is breathing in the cold air, generally colder on my body. Or maybe my brain is just wanting me to go slower because it is less cold.

I wish there were some magical cycling clothing that would allow me to be as comfortable in the cold as more mild temperatures. But, it seems the warmer clothing exaggerates the thermal differences between riding fast on the flat and slow up the climbs. It's not practical to be popping layers on and off every few minutes.

It seems no matter what, I'll still sweat and soak my base layer, even when my skin is ice cold. Ventilate to stay drier and it's simply too cold. High tech breathable fabrics are better than not having them, but still very far from solving this issue.

I just accept my performance drops during the winter and will come back when it warms.

rsbob 

OK I confess, I lied. Today was so cold by my whimpy standards, 34*F, that I pushed myself so hard to first get warm, and second to stay warm, that I almost matched of bettered my PRs on my 30 mile route. Soooooooo, there may be a point where one has to ride harder to keep from freezing.

PeteHski

If you want to look at all these effects on a specific real-world road course then BestBikeSplit is a great online App and you can input actual current or historic weather data, or any generic weather conditions you choose. I use it to predict my finish times for specific events and find it very accurate.

datlas 

Late to the game, but we had a sub-freezing club ride yesterday and we PURPOSEFULLY rode at a more modest pace simply because we know from experience that if we push hard enough to sweat some, it will not go well.

Our usual pace on warmer days for the 50 mile loop: 17.x MPH.
Yesterdays' pace: 15.5 MPH.

So in this case of n=1, 2MPH and done purely to keep a consistent effort and to minimize both overheating and freezing.

Alan K

Two sets of experiences for winter riding around here:
If I’m able ride my road bicycle (no snow or ice on the road), the difference is no more than 10-15% slower in winter but if we have snow or ice on the road and I must ride one of my winter bikes with thicker studded tires then speed takes a serious hit… as much as 1/3rd less. If the snow is still coming down, bike paths get piled with snow (city can’t make multiple cleaning attempts a day, they tend to do it once, early in the morning and then they wait until it has stopped snowing).The more snow on the road/path means slower going.
My cutoff temp for bicycling used to be 10 below 0 F. I think this year, it’s going to be 5 below 0.
Today was a nice sunny and warm day with 40F for high but according to weather wizard, above freezing days are over!

choddo

-10F? Jesus. Those temperatures just do not exist here. Northern Scotland’s record low is -27.2C (-16F) but London has never been below 4F and that was in 1962. Not been close to that in recent years. I’m never complaining about winter riding conditions again.

(having said that, if climate change does knacker the gulf stream, we’ve got a big problem and we’ll need to learn how to deal with real winters)

PeteHski

The thing with UK cold is the relatively high humidity we often see with it. It makes temperatures even slightly above freezing feel much colder than the temperature alone would suggest. I actually find it much easier to live in dry, freezing conditions like we often experience when skiing out in Canada Interior BC, where it is a good 10-20 degC colder.

rumrunn6

enough that I stop keeping track

Alan K

Our bodies are incredible in adapting to our environments (within certain range that is considered compatible with human life).
When visiting those old stone castles where very influential people spent their lives, shaping the world around them, one can’t help but wonder the dampness and cold… but they survived and even thrived.

[My wife’s grandmother once told me that people who are now nostalgic about the good old days, never had to use an outhouse in the middle of Minnesota winter nights!]

It’s the heat of the south that is much more unbearable. For cold weather, you can always add more layers, and we do, but for hot weather, you can take off only so much without getting arrested for public indecency (assuming it’s still a thing). 😉