High-40s/Low50's riding: more or less efficient than 70s/80s?

"David Damerell" wrote in message
...

Well, skiers aren't so concerned about snow and ice.
I commute all year round by bike, but I worry about icy conditions.

I used to also until I invested in studded tires. On the roads I ride
(Boston), ice isn't too frequent, but it's a bit difficult to predict. I
keep studs on one bike during the winter and use it if I think there's any
possibility.

BTW, as another poster has pointed out, your replies are including the
quoted text as an attachment, my security settings require some digging &
cut & paste to respond.

begin quoting dynohubbill :
David Damerell wrote:
I commute all year round by bike, but I worry about icy conditions.
Have you tried the Nokian Hakkepeliitta studded tyre?

I've considered it, but it's not worth it. It is hardly ever icy here -
once or twice a year - and the roads are well gritted. On my commute we
are literally talking about dismounting and walking for thirty feet in
order to avoid the risk of a fall.
--
David Damerell Distortion Field!

Right, I've now been corrected by my girlfriend (biology graduate and
chronic asthma sufferer). Apparently all airways respond unfavourably
to cold air, but in the vast majority of cases it's not a problem. In
some cases it is a definite problem, but only when huge amounts of cold
air are being gulped down. This is usually termed "exercise-induced
asthma". Sufferers usually react especially badly either just after
starting or just after stopping an effort.

Symptoms include excess phlegm, wheezing, coughing or shortness of
breath. Shortness of breath is the one that causes a drop in athletic
performance, which is why riders from Indurain downwards have taken
medical remedies to stop even the slightest wheeze.

A quick Google for "exercise-induced asthma" shows, for example,
http://www.physsportsmed.com/issues/...99/lacroix.htm - which
looks like a seriously academic look at the problem.

"EIA develops when vigorous physical activity triggers airway narrowing
in people who have heightened bronchial reactivity (12). In short, EIA
is a reversible airway obstruction that occurs during or after
exertion; its symptoms include cough, wheezing, dyspnea[shortness of
breath], and/or chest tightness.

EIA can occur in otherwise healthy people who do not have chronic
asthma. Exercise is the only stimulus for their asthma symptoms."

Other information at
http://www.allergyasthma.com/archives/asthma16.html,
http://www.aaaai.org/patients/allerg...ced_asthma.stm
and numerous others.

Bottom line seems to be, if you have trouble with breathing in
excessively cold air, there are medical treatments (most commonly the
blue Salbutamol inhaler) which can help. However, asthma isn't
progressive (i.e. you're not gong to make matters worse) so there's
nothing particular to worry about. In fact given how impressive
"exercise-induced asthma" sounds relative to its actual impact, it's
probably worth hanging on to as an excellent excuse 8-)

cheers
marvin
now far better informed about asthma than he ever expected to be

wrote:
Dear Pete,

It's not your imagination. Riders usually go slower as the
temperature drops for several reasons.

A) Temperature comfort--going slower reduces wind chill
B) Breathing comfort--cold air is denser, but much less fun
C) Clothing aerodynamics--winter clothes = wind drag
D) Raw wind drag--density affects drag more than breathing

The wind drag of the denser cold air is probably the biggest
factor.

This is probably true. Drag force is proportional to air density,
which (using the ideal gas law) increases by 1% for each 3C
decrease in temperature.

The list is missing rolling resistance of the tires, though.
The new edition of Bicycling Science suggests that rolling
resistance increases by 1% for each 1C decrease in temperature.

Not that these are huge effects, but they do reinforce my own
biases. I like to ride when it is hot.

Dennis Ferguson

wrote:
Dear Pete,

It's not your imagination. Riders usually go slower as the
temperature drops for several reasons.

A) Temperature comfort--going slower reduces wind chill
B) Breathing comfort--cold air is denser, but much less fun
C) Clothing aerodynamics--winter clothes = wind drag
D) Raw wind drag--density affects drag more than breathing

The wind drag of the denser cold air is probably the biggest
factor.

This is probably true. Drag force is proportional to air density,
which (using the ideal gas law) increases by 1% for each 3C
decrease in temperature.

The list is missing rolling resistance of the tires, though.
The new edition of Bicycling Science suggests that rolling
resistance increases by 1% for each 1C decrease in temperature.

Not that these are huge effects, but they do reinforce my own
biases. I like to ride when it is hot.

Dennis Ferguson

wrote:
Dear Pete,

It's not your imagination. Riders usually go slower as the
temperature drops for several reasons.

A) Temperature comfort--going slower reduces wind chill
B) Breathing comfort--cold air is denser, but much less fun
C) Clothing aerodynamics--winter clothes = wind drag
D) Raw wind drag--density affects drag more than breathing

The wind drag of the denser cold air is probably the biggest
factor.

This is probably true. Drag force is proportional to air density,
which (using the ideal gas law) increases by 1% for each 3C
decrease in temperature.

The list is missing rolling resistance of the tires, though.
The new edition of Bicycling Science suggests that rolling
resistance increases by 1% for each 1C decrease in temperature.

Not that these are huge effects, but they do reinforce my own
biases. I like to ride when it is hot.

Dennis Ferguson

"Dennis Ferguson" wrote:

The list is missing rolling resistance of the tires, though.
The new edition of Bicycling Science suggests that rolling
resistance increases by 1% for each 1C decrease in temperature.

Not that these are huge effects, but they do reinforce my own
biases. I like to ride when it is hot.

Hmmmm, taking into account my current winter speed at about 5 degrees
C, come the next Arizona summer I should be passing all the cars on
the interstate! ;-)

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $695 ti frame