Things That Affect Speed

Secteur

I have a local route which I do 3-4 times a week it's very hilly and it's 17.5miles long. On average it takes me 1hr 10 mins or thereabouts.

Last Summer I got my time down to 1hr 6mins but over Winter, my times got such that I just couldnt crack 1hr 13m. That includes dry, cold, bright days when the tarmac was dry and days when it wasnt too windy.

A 7 minute difference is pretty significant over such a short ride.

Today it was warm, sunny and only slightly windy for the first time since last year and I went out in light clothing and did a personal best of 1h 5m. Earlier in the week, I did it on a horrible day and got my usual 1hr 14m (I dont recall it being *that* windy).

I push just as hard in the Winter, and as far as I can tell, the only differences are;

1) air temperature
2) wet / icy roads with leaves - i.e. I consciously go a tiny bit slower out of caution, even if I feel like I'm pushing (all those downhill corners probably cost a few seconds each, but this doesnt explain slow times on the cold dry days)
3) heavier clothing + mud guards - slight weight penalty
4) tends to be windier in Winter (anecdotally... is it actually windier in Winter??)
5) possibly running hotter with all the clothing / tights meaning quads & calves at a higher temp and therefore possibly reduced ability - this is a guess??

So, what other factors could be involved in causing such a differential between my speeds on hot & cold days?

I wouldnt have believed that a difference of 20 degrees in air temperature could have such a profound effect?

nickel

When its freezing cold the air is denser than on a warm day, this in turn makes it harder to push your way through the air on your bike. Also I find the mental effect of the cold makes me just not try as hard, both sub consciously and consciously. As you say on cold days I tend to much more cautious on downhill sections and through corners just in case there's ice about.

Secteur

But is there any evidence or data to show how much harder it is to push through cold air than warm air, and would that data support my time differences of as much as 10 minutes over a 1hr 10m course?

Peddle Up!

My entire life is like that. Somedays things are easy, others hard. :?

dodgy

Secteur wrote:

But is there any evidence or data to show how much harder it is to push through cold air than warm air, and would that data support my time differences of as much as 10 minutes over a 1hr 10m course?

Yes, the data is out there, I've seen it before on the Internet. I seem to recall there's a difference of at least 1mph between a cold day and a warm one. Go search for the facts, they're out there somewhere!

nickellis

It was mentioned on the tele during the Track London World Cup round. Day one, heating cranked up into the mid 30s. World records tumbling like the Berlin Wall.

alihisgreat

i'm quicker when its warmer because my lungs don't like the cold air -> apparently its exercise induced asthma!

DonutDad

ALIHISGREAT wrote:

i'm quicker when its warmer because my lungs don't like the cold air -> apparently its exercise induced asthma!

Do you take an inhaler for that? if not you should to think about it - avoid undue stress on your respiratory system and all. I take a couple of puffs before I start every ride, and get no trouble at all during rides.

RoadMeridaBen

Cant say my speed has dropped this winter during the colder weather, garmin logs are pretty much identical to that of the summer. Logic would say you should be slower in the winter though

neeb

One theory I have is that when it's cold, your upper body is more tense, and that makes you a little less aero. Also, the fact that you are wearing more clothes will also make you less aero, both directly (folds, bits flapping about) and indirectly (you are more constrained, again contributing towards making you less flexible and so less aero).

alihisgreat

DonutDad wrote:

ALIHISGREAT wrote:

i'm quicker when its warmer because my lungs don't like the cold air -> apparently its exercise induced asthma!

Do you take an inhaler for that? if not you should to think about it - avoid undue stress on your respiratory system and all. I take a couple of puffs before I start every ride, and get no trouble at all during rides.

no, haven't really thought about that.. used to get mild asthma.. but that was when i was like 5-10?

might bring it up with the GP next time I'm in.

Its not uncomfortable or anything.. just get a bit of a wheeze and cough after exercise in the cold (cycling, football etc.)

Crimmey

I don't like the cold and very humid air, makes me breathe funny. Humidity has been high all winter except one week but I do a lot of night riding when it's at its worst.

itsnotarace

Low tyre pressure can slow you right down

y33stu

Was watching the track championships the other week from London, they keep the air temperature quite high in the Velodrome, and design the buildings to retain the heat around the track. Theory being air is lighter and less dense when its warmer. By that theory, cold air is denser and more difficult to cycle through, leading to slower times.

sungod

Secteur wrote:

But is there any evidence or data to show how much harder it is to push through cold air than warm air, and would that data support my time differences of as much as 10 minutes over a 1hr 10m course?

drag is proportional to air density

air density increases at lower temperatures

depending on relative humidity, air at 0 celcius with be 7% to 8% denser than air at 20 celcius

drag will increase by the same percentage, add on a bit for the effect of the extra clothing and i reckon that accounts for most of the difference you are seeing

tyre pressure is also affected, but unless you are inflating/checking pressure in the warm and riding in the cold there's not going to be much diffence

navrig

Mental attitude. If I am in the zone a route will feel easier than when I am not in the zone. If it feels eaier I will be faster. I attack hills more aggressively and can push for long times on the flats.

navrig

ALIHISGREAT wrote:

i'm quicker when its warmer because my lungs don't like the cold air -> apparently its exercise induced asthma!

I was diagnosed with that when I was about 23. It went away about 2 years later when I moved out of a cold damp flat into a house with central heating. It stayed away until I later moved into a house with a cat. Once it went away I was able to abandon the inhaler.