We are getting unusually cold conditions for this part of the world, so I'm not used to this.

It was -15C during most of my morning ride, and -11 on the way home. No snow on the road, and almost no ice.

What has shocked me is how slow I was. I'd expect to do the 27.5 mile trip in 1hr40, but it took me 2 hours on the way in and a bit more on the way home. I'm utterly exhausted today (took the train instead of riding). Coupled with that, my eyes are sore, like I've had a flash burn in the face.

Could the slow riding and exhaustion just be because of the cold? I was well wrapped up and only my toes got a little cold.

If I'm not mistaken, rolling resistance is a bit higher when it's cold out. I know I experienced the same thing commuting yesterday. I was quite a bit slower than I usually am, and the cold may have had something to do with it. Or maybe it's because I didn't get as much sleep as I should of the night before or because I haven't checked my tire pressure in over a week and they were low. Whatever the case was, the commutes definitely took longer.

I find my self much slower in the cold especially in the mornings, even when there is no snow. But i hear ya yesterday i was running late to an appt. after work so i rode hard the whole trip there (5mi) not only did it take 30min but i was just about dead when i arrived, and it was pretty warm by your standards (around 30f) I have also found that the more the temp drops the slower you ride i wonder if theres a point where they jsut even out?

I find that the main slowing factors are studded or heavier tires, winter clothes (boots, heavy pants, etc.), and the greater winds.

The main factor where the cold plays in that I know of is wind chill. Riding faster makes you feel more wind, so if you're cold there's a trade-off between pedaling harder to warm up (generating more heat) and going slower to lessen the wind (losing heat less slowly).

This is all assuming perfectly clear roads, if there's snow that'll slow me down. A lot...

^^Yes snow multiplies the slowness effect by a million% Even today though riding on my slicks i was riding along at about 17-19mph, two months ago when morning temps where in the mid 50's i would be at 20-22mph, im not by any means a well educated person but, are we using more calories in the cold or something. I mean i understand the eyes thing in the cold i get the same thing, but im sure everyone here will probably say their times are slower in the cold there has to be a reason.

Yes that is true. The amount of calories used to keep the body warm goes up as the temperature goes down. This is offset somewhat by heat being generated while cycling. But then again the faster you go the faster you lose heat from the wind.

There is an inverse effect in warm temperatures, where overheating causes more calories to be used.

There is probably an optimal temperature range in which you can go fastest and anything much above or below that will be slower. Though its harder to tell on the colder end, because of all the other slowing down factors in the winter. In the heat the only thing that slows you down is the extra water you have to carry

The primary reason I am slower in cold weather is that I simply don't want to exert myself to the same level and start sweating, and then get cold. Also, I don't think muscles work as efficiently as the temperature drops. Other reasons are that I am carrying extra weight in clothing and lights, and I use heavier tires in cold weather for better flat protection. Also, friction on moving parts increases, tires have increased rolling resistance, the air is denser at lower temperature, but I think these are less significant. Every little bit adds up to a noticeably slower ride.

Alright the more i think about it, we're all right i think it is just a bunch of factors bunching up to create the slowness. I think after this winter of riding the giant with its studs and 40+pounds of gear i carry everyday going through the snow im gonna buy a full C/F roadie just to see how fast i can go on the flats.

...

feels like riding on a trainer with the resistance cranked too high.

last week, i thought something was wrong with my bike, so i re-lubed my chain and freewheel but it was still sluggish. i'll just look at it as a better workout

I didn't even think of the density of air... It increases about 4% for each 10 degree Celsius decrease in temperature (about 20F).

On my commute in today I forgot goggles or glasses. Too concerned about the other extremities to think about eye ware I guess.

The temp was really low and my eyes were watering nearly the entire way. The faster I went the harder it was to see. They are not sore yet, but I still have the commute home to look forward to.

Thats gotta suck for you folks at or near sea level with your already thick air

I've heard all kinds of theories about why it is slower going in the winter. All I know for sure is it slows me down.

What you describe is pretty much a universal phenomenon as far as I can tell. In the cold you are slower. There are several reasons for this. The air is more dense when colder and offers more resistance. You are wrapped up and are less aerodynamic. You have more material binding at the joints and are heavier. The tires rolling resistance is higher. Hub grease is stiffer. The body is getting the message that it is cold outside (even if you are bundled up) and the brain will restrict some fluid flow to areas near the surface of the skin. Because of this the muscles and joints do not perform as well. I also believe that the slowing down of the body is an attempt to conserve calories and heat for survival.

It is hard to get your mind wrapped around this when you seem a lot slower than usual. Generally, if you try to ride at your normal warm speed you will feel like you are riding into a wall. You simply have to slow down. If you normally can ride 30 miles at 20 mph in the warm weather. You will probably have to exert about the same effort to go 15-20 miles at 15-17 mph. But this may vary from person to person. The younger that you are the less you may be effected.

Ive found that in addition to all the mentioned reasons for slowing down in winter is Hydration. It seems so much easier to get dehydrated in the winter and that affects the eyes as well as your reserve energy. Drink Up!!

1)Thicker air in the cold.
2)As the air inside your tires gets cold the pressure goes down, unless you correct it, you are riding with less tire pressure, more rolling resistance.
3)Tires and tubes are harder to bend in the cold, even more rolling resistance.
4)Grease can be a lot thicker in the cold, in the BB, the wheels, the pedal bearings, and the pawls inside your freehub or freewheel. If it gets cold enough some pawls don't go back and forth and the cogs just spin. It varies with different greases.
5)Chain lube is stiffer in the cold.
6)Winter clothing makes you heavier. Weigh your entire cold weather outfit. It could be ten lbs. an easy five.
7)With thicker clothing it is more work to bend your hips, knees and your ankles as you pedal. When is is below 20F this is a big factor for me, I have a lot of layers on.
8)Extra calories are used to keep warm in the cold no mater what you do.
9)Even thought it tastes better to many, drinking cold water requires calories to heat it up inside you.
10)It is more often windy in winter where I live. YMMV.
11) It's often harder to stay in peak condition when the weather is lousy.
12) I gain weight in the winter, YMMV.

Like just about everything in cycling, the end result is the total of many small things added together. Summer or winter.

Good points, I believe you are correct about the attempt to conserve calories and heat for survival, too.

I wonder if there are is a single factor that would act to make you go faster in the winter (in the absence of the billion factors that have been mentioned that will slow you down).

Sometimes there are huge winds, I guess if it's a tailwind that'll make you go faster. I've had that happen once or twice.

And then brakes failing... That could make you go faster than you would want, until something else causes you to stop

Yeah pretty bleak on the speed front.

coffee !!!!!!!!

Went out to check the bike last night - found a flat tyre. Slow leak, so I guess on Monday I was probably struggling against that.

No snow or ice today, no flat, 10min faster.

I agree with most all of the reason cited by others here. But #1 reason for me has to be the sluggishness of the studded tires on my bikes. #2 is probably bulky clothing.

Not to be silly, but I think the single biggest thing that can help you go a lot faster in winter is if you have a large heated indoor velodrome near where you live.

The faster you go the colder it gets...

the cold doesn't necessarily slow me down, but it tires me out to keep up the same pace. by the time I get to work, I'm exhausted instead of exhilarated.