Cold and speed

[Robert Siegel]

For the last couple of weeks of chilly weather I've been averaging 15+ mph for my 10 and 13 mile
daily rides. Today the temp hit 75 mid afternoon and I averaged 15+ mph for 10 miles --- BUT BUT BUT
-- today I rode without the fairing on tires that had not been pumped up for the last 5 days. (Tires
are usually kept at 120/120 psi front and rear.) It was late in the day so I did not take the time
to pump the tires or put the fairing back on after a cleaning.

--
Gator Bob Siegel EasyRacers Ti Rush

 

[Bethf]

"Robert Siegel" <[email protected]> wrote in message
news:[email protected]...
> For the last couple of weeks of chilly weather I've been averaging 15+ mph for my 10 and 13 mile
> daily rides. Today the temp hit 75 mid afternoon
and
> I averaged 15+ mph for 10 miles --- BUT BUT BUT -- today I rode without
the
> fairing on tires that had not been pumped up for the last 5 days. (Tires are usually kept at
> 120/120 psi front and rear.) It was late in the day
so
> I did not take the time to pump the tires or put the fairing back on
after
> a cleaning.

I am slower if my muscles feel cold.

 

[Tbradster]

Welcome to the winter penalty. Below about 40 degrees F, I slow down. Heavy air or heavy clothing,
the colder it gets, the slower I go.

I take some comfort in the fact that usually in very cold conditions, I am the only sorry gump out
on a bike...

Rode the Linear to work today, 16 degree, snow. Enjoyed the ride, though.

Brad

 

[Tom Sherman]

Robert Siegel wrote:
>
> For the last couple of weeks of chilly weather I've been averaging 15+ mph for my 10 and 13 mile
> daily rides. Today the temp hit 75 mid afternoon and I averaged 15+ mph for 10 miles --- BUT BUT
> BUT -- today I rode without the fairing on tires that had not been pumped up for the last 5 days.
> (Tires are usually kept at 120/120 psi front and rear.) It was late in the day so I did not take
> the time to pump the tires or put the fairing back on after a cleaning.

Robert,

The pressure in your tires will increase with the ambient temperature, which could account for some
of your speed increase.

Tom Sherman - Quad Cities USA (Illinois side) Various HPV's

 

[Robert Siegel]

Yes ... but to counter that I find that the Stelvios do go down considerably after 3 days. And the
actual high this pm was only 72.5...I just checked. Felt warmer. ;-)) Midday temps hereabouts have
stayed (mostly) in the low 50s for the last 10 days or so.

Also, I usually pump my tires before riding to 120/140 front and rear.

--
Gator Bob Siegel EasyRacers Ti Rush "Tom Sherman" <[email protected]> wrote in message
news:[email protected]...
>
> Robert Siegel wrote:
> >
> > For the last couple of weeks of chilly weather I've been averaging 15+
mph
> > for my 10 and 13 mile daily rides. Today the temp hit 75 mid afternoon
and
> > I averaged 15+ mph for 10 miles --- BUT BUT BUT -- today I rode without
the
> > fairing on tires that had not been pumped up for the last 5 days.
(Tires
> > are usually kept at 120/120 psi front and rear.) It was late in the day
so
> > I did not take the time to pump the tires or put the fairing back on
after
> > a cleaning.
>
> Robert,
>
> The pressure in your tires will increase with the ambient temperature, which could account for
> some of your speed increase.
>
> Tom Sherman - Quad Cities USA (Illinois side) Various HPV's

 

[Howard Bishop]

Under contributing factors, think about this... Density altitude is the height above mean sea level
adjusted for deviations from standard temperature and pressure (humidity has an impact too, but it
is harder to measure in flight and usually not counted). Cool temps, high pressure, and low humidity
all conspire to decrease density altitude. Consider a person at 6000 feet MSL (per surveyor's
claim). On a cool, high pressure, low humidity (and these things do run together) day, the density
altitude might be as low as 3000 feet or less. On a hot sticky day, with lots of haze, the density
altitude might be closer to 10000 ft. That is, the cooler, dryer day with low humidity gives you the
same thickness of air to push through as you would find at or below sea level (think cold butter).
The warmer day, especially with low pressure, gives you air "thickness" normally found far above
your normal station in life (think warm butter on a pancake). Bottom line is you have less aero drag
on warm days - several percent less. There's a nifty circular slide rule for calculating this sort
of thing (an E6-B).

For this reason there is a well known time-trial course between Moriarty and Estancia NM. Autos are
affected by this phenomenon as well; fuel economy goes down with cold air - both for combustion and
drag reasons, but increases during the summer.

 

[Robert Siegel]

FYI 2

Thanks! That is very interesting. That would partially explain why I am considerably faster in warm
air with the same effort. Warm muscles and ease of breathing pre-warmed air also might contribute.

--
Gator Bob Siegel Easy Ti Rush "Howard Bishop" <[email protected]> wrote in message
news:[email protected]...
> Under contributing factors, think about this... Density altitude is the height above mean sea
> level adjusted for deviations from standard temperature and pressure (humidity has an impact too,
> but it is harder to measure in flight and usually not counted). Cool temps, high pressure, and low
> humidity all conspire to decrease density altitude. Consider a person at 6000 feet MSL (per
> surveyor's claim). On a cool, high pressure, low humidity (and these things do run together) day,
> the density altitude might be as low as 3000 feet or less. On a hot sticky day, with lots of haze,
> the density altitude might be closer to 10000 ft. That is, the cooler, dryer day with low humidity
> gives you the same thickness of air to push through as you would find at or below sea level (think
> cold butter). The warmer day, especially with low pressure, gives you air "thickness" normally
> found far above your normal station in life (think warm butter on a pancake). Bottom line is you
> have less aero drag on warm days - several percent less. There's a nifty circular slide rule for
> calculating this sort of thing (an E6-B).
>
> For this reason there is a well known time-trial course between Moriarty and Estancia NM. Autos
> are affected by this phenomenon as well; fuel economy goes down with cold air - both for
> combustion and drag reasons, but increases during the summer.