Minnesota Randonneur Theory of Speed vs Temperature for Winter Riding

[RandoRob]

Despite my best efforts, I have been dragged into riding winter permanents again this year.   There is nothing wrong with having good friends insist you ride with them, but once the temperature starts dropping, I try to find polite ways to stay busy indoors or head south for a while to miss the worst of our Minnesota winters.  However, aside from my winter wussiness, we have a good contingent of hardy winter randonneurs who enjoy getting out whenever they can to card winter perms to earn Minnesota Natural R-12s, or just because they love to ride. 

 

Over the course of the past two winters in particular we have had a wide range of mild to pretty extreme winter riding experiences and have evolved a theory about how to predict how fast a given rider can expect do a typical permanent route in the winter, based on how long it would take them to do the route in the summer (at 60-80 above) under average conditions, compared to progressively colder weather, starting at 50 above down to zero degrees Fahrenheit. 

 

We don't admit to a high level of scientific rigor in the process of developing this theorum but we have a lot of anecdotal experience and a good number of examples to work with from a range of randonneurs, faster and slower. 

 

Here is our theorum, open for comments and enhancement by others who may have similar experiences riding in winter months. 

 

BTW - my apologies to the southern belt of the country who may not have as much concrete data or experience to contribute to this topic, not that this would hold anyone with an opinion back from expressing it, but our suggestion to the warm weather folks would be to conduct a similar set of tests on riding speed and time at temps > 80 and report back.  

 

The Minnesota Randonneur Theory of Speed vs Temperature for Winter Permanent Rides

 

Starting at 50 above, for every 10 degrees colder, your net average speed will drop by 1.5 mph

 

Example  #1

If you normally ride a particular 200k permanent in 10 hours under typical summer conditions (i.e. average temp 60-80 above), your net average riding speed is 12.5 mph. (125 miles / 10 hrs)

 

If the temperature averages 30F during the day while you are riding, your net average speed, via the above formula is 

                12.5mph - (1.5mph x (50 degrees - 30 degrees) /10 degrees) = 9.5 mph for the same course

Thus, your time to complete is predicted to be 13.1 hours, which we have validated +/- 1/2 hour or so

   

Example #2

If we take some faster riders, capable of riding the same perm in 8 hours under summer conditions, but now the average temperature is 0 while they are riding, their net average speed would be 

                  15.6mph  - (1.5mph x (50 degrees - 0 degrees) /10 degrees ) = 8.1 mph

Time to complete is predicted to be 15.4 hours, which is what it took two of our strong riders last January.  They had studded tires, lots of layers of good winter gear and rode 1/3 of the ride in the dark. They didn't get credit from RUSA for that ride, but are local legends here for their persistence.  They were exhausted when they completed the ride.  A few weeks later they did the same ride in 20F temps and made it in a little under 11 hours (11.25 was the formula prediction) 

 

Why we think this theory works, for typical randonneur winter riders: 

 

    - additional clothing and foot gear is needed as the temperature drops which constricts your movements and adds weight

    - it gets more difficult to drink/eat on the bike as it gets colder.  Water bottles freeze, Camelbacks help, but tubes freeze too

    - wider, knobby or possibly studded tires needed in cold or icy weather with icy/snowy roads slow you down. 

    - drive trains get mushier as lubrication thickens, shifting is often not as crisp

    - breaks take longer because you have more clothing to take off and put back on

    - it takes longer to warm up after a break

    - it takes energy to exist in cold weather, even when you have good winter clothing on.

    - riding near the winter solstice, especially in the northern tier states, minimizes your daylight hours so - as you ride slower, you will end up riding more in the dark, so you will likely ride even slower

 

We are continually validating and refining this theory so the numeric factors may vary and there may well be other considerations, but we believe the basic tenets make sense and we are comfortable sharing our theorum with the randonneur world and believe it will be accepted by most winter riders on longer distance rides as a reasonable predictor of finishing time on typical permanent rides.  

 

Comments, challenges and corroborating information is welcome.

 

Rob Welsh  :-)

Minnesota RBA

 

[Alan Walker]

Apart from awe and astonishment, I have nothing to add.  That you specify 50 above, not just 50 is .... alarming.

 

Cheers

Alan

P.S. It's 90 deg F at 9:15 p.m. here in Victoria, Australia.

 

 

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[Jan Heine]

At 12:44 AM -0800 1/17/12, RandoRob wrote:

> - wider, knobby or possibly studded tires needed in cold or
>icy weather with icy/snowy roads slow you down.

Obviously, slush will slow you down just by itself. But even here in
Seattle, on dry roads, we go slower when it's cold. In addition to
the factors you mentioned, there is a factor that often is overlooked:

Rubber becomes harder as it gets colder. Harder rubber rolls less
well. We and others have documented many times that tires roll faster
in warmer conditions. For Bicycle Quarterly's tire tests, we had to
correct for temperature when comparing measurements taken on
different days. (We do this by always testing a reference tire.)

The difference is not insignificant.

Jan Heine
Editor
Bicycle Quarterly
http://www.bikequarterly.com

Follow our blog at http://janheine.wordpress.com/

[George Swain]

Rob,

At last some science to help me feel a bit better about being such a
sloth! I was trying my best to rationalize why it had taken me an
extra several hours to finish a beloved permanent last week and this
is just the ticket. When I consulted the forecast, I forgot to factor
in the 15 degree drop in temperatures that came at 2200 feet. Note to
self - save the mountainous rides for spring . . .

Happy riding. While not Minnesota, I'm shooting for a "natural"
upstate New York R12 this year, which might actually not be as hard as
in years past.

Best,

George
http://thehudsonvalleyrandonneur.blogspot.com/2012/01/are-we-cold-yet-catskill-climbfest-200k.html

On Jan 17, 3:44 am, RandoRob <rgwe...@aol.com> wrote:
> Despite my best efforts, I have been dragged into riding winter permanents

> again this year*.  * There is nothing wrong with having good friends insist

> you ride with them, but once the temperature starts dropping, I try to find
> polite ways to stay busy indoors or head south for a while to miss the
> worst of our Minnesota winters.  However, aside from my winter wussiness,
> we have a good contingent of hardy winter randonneurs who enjoy getting out
> whenever they can to card winter perms to earn Minnesota Natural R-12s, or
> just because they love to ride.
>
> Over the course of the past two winters in particular we have had a wide
> range of mild to pretty extreme winter riding experiences and have evolved
> a theory about how to predict how fast a given rider can expect do a
> typical permanent route in the winter, based on how long it would take them
> to do the route in the summer (at 60-80 above) under average conditions,
> compared to progressively colder weather, starting at 50 above down to zero
> degrees Fahrenheit.
>
> We don't admit to a high level of scientific rigor in the process of
> developing this theorum but we have a lot of anecdotal experience and a
> good number of examples to work with from a range of randonneurs, faster
> and slower.
>
> Here is our theorum, open for comments and enhancement by others who may
> have similar experiences riding in winter months.
>
> BTW - my apologies to the southern belt of the country who may not have as
> much concrete data or experience to contribute to this topic, not that this
> would hold anyone with an opinion back from expressing it, but our
> suggestion to the warm weather folks would be to conduct a similar set of
> tests on riding speed and time at temps > 80 and report back.
>

>  *The Minnesota Randonneur Theory of Speed vs Temperature for Winter
> Permanent Rides*
>
> *Starting at 50 above, for every 10 degrees colder, your net average speed
> will drop by 1.5 mph*

[Christian]

This is good to know and MUST explain why I was so slow Sunday during
my three hour, 24-35 degree ride.

Best wishes,

Christian

[pmathews]

And the pros in the Tour Down under were riding in over 40C (111F).  Imagine how fast they would go on a cold day!

Peter

-- 
Peter Mathews, pmat...@alphalink.com.au,
Bikephone: 043 999 2130 
Bikemail: pmathe...@gmail.com

[Wayne J]

> >     /Starting at 50 above, for every 10 degrees colder, your net
> >     average speed will drop by 1.5 mph/

Interesting topic. My guess is that going from 40 to 30 would slow one
down more than going from 50 to 40. At 40 degrees, the roads aren't
going to be icy, and clothing can still be pretty normal.

[Steve Palincsar]

Roads aren't necessarily going to be icy at 30, either. But there's
definitely a change in the clothing required between the 40-50 range and
30-40.

[RandoRob]

After reviewing what I wrote yesterday along with the good comments in the past day, I would add that our calculation showing the relationship between speed and colder temperatures is linear for simplicity, but actually  the impact of riding in cold weather gets more drastic as the temps get colder.  At lower temps many factors, extra clothing, frozen water bottles, more dark hours and often slicker conditions all combine to slow you down even more. 

 

There is a winter ultra marathon race in Northern Minnesota every year (The Arrowhead) covering 135 miles on frozen logging and other packed snow roads.  The winner last year, in near record time, averaged 8.5 mph.  Temps often get down to -20 or colder at night for this event.  One of our randonneurs, who normally completes a reasonably challenging 200k brevet or permanent in 10-11 hours in the summertime took 34 hours to complete the Arrowhead last year.   I doubt that we would be able to establish a RUSA brevet or permanent for this course. 

[Paul Slavchenko]

The density of air is inversely proportional to temperature, measured
in absolute degrees Kelvin. Therefore, wind resistance increases in
cold temperatures, dropping speed. Up here in Canada, where I ride all
winter, no matter how much I train and exert myself, my average speed
falls by about 10% when the temperature falls by 10% (say from 27C to
-3C). I would agree that all of the other considerations apply as
listed in the other posts.

Paul

[Richard | DistanceBiker.com]

Paul,
I thought there was less wind resistance when it is cold. My pilot friends say it is safer to fly on cooler days, as smaller propeller-driven planes don't do well in 90-100F temps (at least at 5,000 to 12,000 feet).
But yes, the whole theory is true....winter riding is a much slower proposition, despite the fact that one may have equal fitness in the winter.
> Richard Stum
6430 ft in Central Utah

[Bill Gibson]

It's easier to fly in dense air. Low density air means less lift! Very limiting to helicopters. For cycling, it's easier to breathe in high density air, but I run out of breath up high if I'm not acclimated. But I can feel the difference in the wind on my skin and in my hair!

I never worry about my absolute speed, just my airspeed.

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[NickBull]

Hi, Rob,

I definitely think that cold weather slows me down. But not by as
much as your Minnesota Theory (1.5 mph for every ten degrees below
50F), because at my overall average speed of 11.2 mph on 200Km's, then
I'd never finish in time at 20F! If I had to use studded tires on a
ride, then I know that I'd get slowed down another two or three mph,
so timely completion would be in serious doubt. My hat is off to your
riders who finished a 200Km on studded tires

Anyway, I was curious just how much I get slowed down by the cold, so
I ran a test of your theory against my own data, and found a slowdown
of about 1/4 mph of average speed for every ten degree temperature
drop below 50F. Moving speed actually slows down by about 0.4 mph for
every ten degree temperature drop. But I think I compensate for
riding more slowly by controlling faster. Plus, whenever you are
stopped, you are getting cold, so the best way to stay warm is to keep
moving.

Data source: I have GPS data and (approximate) temperature records for
each 5 mile leg for all my rides since 2006. The temperature records
for each leg are interpolated from knowing the high and low for the
ride, but I know that it's moderately accurate since I can compare the
interpolation to my recollection of the day. For rides of around
200Km, I have a total of about 16000 miles of data, of which about
5110 miles are at temperatures below 50, and 1200 miles at
temperatures below freezing (but so far, no rides below zero). The
regression also controls for rider weight, bike weight, rate of climb,
rate of descent, cumulative climbing on the ride, cumulative distance
on the ride, whether I'm drafting, whether it's night, and whether I'm
sick.

If I restrict attention to solo brevets that I know I was riding as
hard as I could, and only look at the effect of "extreme" temperatures
(below freezing or above 90) then I find that extreme temperatures
slow my moving average speed from 13.3 mph to 12.6 mph. Night-riding
has about the same effect, as does carrying 10 pounds more weight (ten
pounds extra on the bike is not as bad as ten pounds extra on the
rider).

Nick

On Jan 17, 3:44 am, RandoRob <rgwe...@aol.com> wrote:

> Despite my best efforts, I have been dragged into riding winter permanents

> again this year*.  * There is nothing wrong with having good friends insist

> you ride with them, but once the temperature starts dropping, I try to find
> polite ways to stay busy indoors or head south for a while to miss the
> worst of our Minnesota winters.  However, aside from my winter wussiness,
> we have a good contingent of hardy winter randonneurs who enjoy getting out
> whenever they can to card winter perms to earn Minnesota Natural R-12s, or
> just because they love to ride.
>
> Over the course of the past two winters in particular we have had a wide
> range of mild to pretty extreme winter riding experiences and have evolved
> a theory about how to predict how fast a given rider can expect do a
> typical permanent route in the winter, based on how long it would take them
> to do the route in the summer (at 60-80 above) under average conditions,
> compared to progressively colder weather, starting at 50 above down to zero
> degrees Fahrenheit.
>
> We don't admit to a high level of scientific rigor in the process of
> developing this theorum but we have a lot of anecdotal experience and a
> good number of examples to work with from a range of randonneurs, faster
> and slower.
>
> Here is our theorum, open for comments and enhancement by others who may
> have similar experiences riding in winter months.
>
> BTW - my apologies to the southern belt of the country who may not have as
> much concrete data or experience to contribute to this topic, not that this
> would hold anyone with an opinion back from expressing it, but our
> suggestion to the warm weather folks would be to conduct a similar set of
> tests on riding speed and time at temps > 80 and report back.
>

>  *The Minnesota Randonneur Theory of Speed vs Temperature for Winter
> Permanent Rides*
>
> *Starting at 50 above, for every 10 degrees colder, your net average speed
> will drop by 1.5 mph*