Easy way to calculate grade?

[Bruce Frech]

"Phil, Squid-in-Training" <[email protected]> wrote in
message news:[email protected]...
> Bruce Frech wrote:
> > Find the biggest gear you can use while standing and without pulling
> > up on the handlebars. Then compute as follows:
> >
> > compute the inverse of 4 times the gear ratio.
> >
> > For example if you can climb in a 42-21 then you get 4 * 42 / 21 = 8,
> > and 1/8 = 0.125 = 12.5%
> >
> > Why is this a good guess? 4 = 2 * 2,
> > one 2 is because the crank is about half the radius of the wheel
> > the other 2 is because you apply force about half the rotation of
> > the stroke
> >
> > Then adjust the factor of 4 to suit your style. Perhaps you know a
> > slope of a steep hill, so try to find the biggest gear you can use.
> >
> > You could also try to choose a gear that you can balance (speed =
> > zero) with all your weight on one pedal, and then the slope would be
> > just (radius of crank)/(radius of wheel)/(gear ratio), or 1/(2*gear
> > ratio). But you would have to correct for the ratio of your weight
> > (applied to the pedal)/(total weight including the bike).
>
> So (1/(2*gear ratio)) * (my weight/total weight) would be an appropriate
> number? I might try both methods and see how close they match.
>
> --
> Phil, Squid-in-Training
>
>

The first method is for riding (with a constant of about 4). You ride
carefully but still you only apply vertical force about half the
circumference. And it's easy to use on any hill steep enough to ignore air
resistance. You just have to learn what that constant is for your style.

The second method (with a constant of about 2) is static. You are not
riding but balancing. So it uses all of your force. But this is a hard
method to implement while your buddies are cranking away from you and
laughing.

Bruce

 

[David L. Johnson]

On Thu, 09 Sep 2004 20:15:34 +0000, Phil, Squid-in-Training wrote:

> There's a hill nearby whose gradient or whatever I'd like to guess. How
> should I go about it? I don't have any surveying equipment, and my GPS is
> long gone. I've got a bike and myself.

I did this once with a 4-foot long carpenter's level and a ruler. Pick
several representatives spots on the climb, put front of level on road,
hold horizontally, then measure distance down to the road from the back
end of the level. (inches/48)*100 = grade percentage.

--

David L. Johnson

__o | What is objectionable, and what is dangerous about extremists is
_`\(,_ | not that they are extreme, but that they are intolerant.
(_)/ (_) | --Robert F. Kennedy

 

[[email protected]]

Carl Fogel writes:

> Normally, TinyURL seems to work just fine, but even a few months ago
> they occasionally ignored me as calmly as if I had invited them to
> have dinner and go to a movie afterward instead of demanding an
> instant internet service.

> Since they're free, I decided not to sue them.

> I was just pleased to have learned of www.snipurl.com, which seems
> to offer the same sort of service.

It doesn't seem to take the URL from the one currently on the screen
and convert it. How am I supposed to get a snipped URL from some
endless string on the screen? TinyURL just pops up and says "You have
a tiny URL in your catch" and I then hit the "Back" arrow to the URL
it captured before pasting the TinyURL into the message I am writing.

Jobst Brandt
[email protected]

 

[[email protected]]

Jim Smith writes:

> Aren't watch like things strapped to wrists working at a constant
> temperature? I thought this was part of the reason why watches
> generally keep better time than clocks?

That may have been true for mechanical time pieces but newer ones run
on a crystal frequency that is far more accurate. Take for instance
the clock in the dashboard of a car that sees human fatally high and
low temperatures, yet keeps accurate time. At least the ones in the
cars that I use do so over years.

Jobst Brandt
[email protected]

 

[[email protected]]

On Fri, 10 Sep 2004 14:59:57 GMT,
[email protected] wrote:

>Carl Fogel writes:
>
>> Normally, TinyURL seems to work just fine, but even a few months ago
>> they occasionally ignored me as calmly as if I had invited them to
>> have dinner and go to a movie afterward instead of demanding an
>> instant internet service.
>
>> Since they're free, I decided not to sue them.
>
>> I was just pleased to have learned of www.snipurl.com, which seems
>> to offer the same sort of service.
>
>It doesn't seem to take the URL from the one currently on the screen
>and convert it. How am I supposed to get a snipped URL from some
>endless string on the screen? TinyURL just pops up and says "You have
>a tiny URL in your catch" and I then hit the "Back" arrow to the URL
>it captured before pasting the TinyURL into the message I am writing.
>
>Jobst Brandt
>[email protected]

Dear Jobst,

Alas, I'm a computer consultant and therefore baffled by
these things. (Think of the old Bob Newhart episode in which
Jerry the orthodonist is startled to hear that people have
32 teeth--really? That many?)

I just blue-highlight my prey in Windows by left-clicking on
it, holding down the button, and dragging the mouse around,
hit ctrl-c to copy it to a buffer, click wherever I want to
paste it, and press ctrl-v to paste it.

I think that tinyurl offers to automate this process in
various convenient ways, but I'm overwhelmed by all dozens
of other programs, all getting in each other's way as they
try to be helpful.

I expect that snipurl is equally helpful in some maddeningly
different fashion.

Of course, how well such features work outside of Windows is
another matter.

Ned Ludd

 

[[email protected]]

On Fri, 10 Sep 2004 08:31:38 GMT, Joe Faust
<[email protected]> wrote:

>On Thu, 09 Sep 2004 20:15:34 GMT, "Phil, Squid-in-Training"
><[email protected]> wrote:
>
>>There's a hill nearby whose gradient or whatever I'd like to guess. How
>>should I go about it? I don't have any surveying equipment, and my GPS is
>>long gone. I've got a bike and myself.
>
>I can find the gradient quite easily with my Polar S710 heart rate
>monitor software. I just select the portion of the trip curve that I
>am interested in and the gradient appears in a box below the chart.

Dear Joe,

I'm ignorant of these things, so I have to ask.

Do you know how the monitor figures out gradient? Does it
measure gradient by GPS or by pressure altimeter or by
correlating speed and power or what?

Carl Fogel

 

[Joe Faust]

On Fri, 10 Sep 2004 12:37:27 -0600, [email protected] wrote:

>On Fri, 10 Sep 2004 08:31:38 GMT, Joe Faust
><[email protected]> wrote:
>
>>On Thu, 09 Sep 2004 20:15:34 GMT, "Phil, Squid-in-Training"
>><[email protected]> wrote:
>>
>>>There's a hill nearby whose gradient or whatever I'd like to guess. How
>>>should I go about it? I don't have any surveying equipment, and my GPS is
>>>long gone. I've got a bike and myself.
>>
>>I can find the gradient quite easily with my Polar S710 heart rate
>>monitor software. I just select the portion of the trip curve that I
>>am interested in and the gradient appears in a box below the chart.
>
>Dear Joe,
>
>I'm ignorant of these things, so I have to ask.
>
>Do you know how the monitor figures out gradient? Does it
>measure gradient by GPS or by pressure altimeter or by
>correlating speed and power or what?
>
>Carl Fogel

It is not the monitor that figures the gradient. Just a mathematical
algorithm in the software that calculates the slope from the distance
and ascent.

Joe

 

[[email protected]]

On Fri, 10 Sep 2004 22:37:33 GMT, Joe Faust
<[email protected]> wrote:

>On Fri, 10 Sep 2004 12:37:27 -0600, [email protected] wrote:
>
>>On Fri, 10 Sep 2004 08:31:38 GMT, Joe Faust
>><[email protected]> wrote:
>>
>>>On Thu, 09 Sep 2004 20:15:34 GMT, "Phil, Squid-in-Training"
>>><[email protected]> wrote:
>>>
>>>>There's a hill nearby whose gradient or whatever I'd like to guess. How
>>>>should I go about it? I don't have any surveying equipment, and my GPS is
>>>>long gone. I've got a bike and myself.
>>>
>>>I can find the gradient quite easily with my Polar S710 heart rate
>>>monitor software. I just select the portion of the trip curve that I
>>>am interested in and the gradient appears in a box below the chart.
>>
>>Dear Joe,
>>
>>I'm ignorant of these things, so I have to ask.
>>
>>Do you know how the monitor figures out gradient? Does it
>>measure gradient by GPS or by pressure altimeter or by
>>correlating speed and power or what?
>>
>>Carl Fogel
>
>It is not the monitor that figures the gradient. Just a mathematical
>algorithm in the software that calculates the slope from the distance
>and ascent.
>
>Joe

Dear Joe,

So there's an internal pressure altimeter recording
elevation change and calculating slope for the distance from
the odometer--am I right? Or is it a GPS for the elevation?

Carl Fogel

 

[Joe Faust]

>>
>>It is not the monitor that figures the gradient. Just a mathematical
>>algorithm in the software that calculates the slope from the distance
>>and ascent.
>>
>>Joe
>
>Dear Joe,
>
>So there's an internal pressure altimeter recording
>elevation change and calculating slope for the distance from
>the odometer--am I right? Or is it a GPS for the elevation?
>
>Carl Fogel

Yes, it is an altimeter in the S710 HRM recording elevation change. It
can be reset to the correct altitude before each ride, however I never
bother with it. The relative change works just as well for displaying
climbs, descent, and gradient.

Joe

 

[Phil, Squid-in-Training]

> The second method (with a constant of about 2) is static. You are not
> riding but balancing. So it uses all of your force. But this is a
> hard method to implement while your buddies are cranking away from
> you and laughing.

As a trials/street rider, this is pretty much SOP
--
Phil, Squid-in-Training

 

[John McGraw]

Joe Faust <[email protected]> wrote in message news:<[email protected]>...

> >Dear Joe,
> >
> >So there's an internal pressure altimeter recording
> >elevation change and calculating slope for the distance from
> >the odometer--am I right? Or is it a GPS for the elevation?
> >
> >Carl Fogel
>
> Yes, it is an altimeter in the S710 HRM recording elevation change. It
> can be reset to the correct altitude before each ride, however I never
> bother with it. The relative change works just as well for displaying
> climbs, descent, and gradient.
>
> Joe

If the Polar S710 altimeter is temperature compensated, you can get
reliable altitude #s. If not, some days you may get lucky & get
accurate #s. But you have no way of knowing. I carefully read Polars
specs a few years back (~'98) & couldn't tell. So I called them & got
a negative answer. I believe this was before the S710 & hi'er models.
You've got my curiosity; I think I'll go check their site.

Best, John