Cyclocomputers with 'current grade' measurement - how do they work?

[none]

How is it that some cyclocomputers are able to measure the grade of a
road? Will this be an accurate measurement?

Thanks,
-Mike

 

[[email protected]]

Mine uses change in altitude and distance to compute grade.

 

[Lou Holtman]

none wrote:
> How is it that some cyclocomputers are able to measure the grade of a
> road? Will this be an accurate measurement?
>
> Thanks,
> -Mike

They can be accurate but there will be a delay. You just measure
altitude gain and distance travelled. In a long even climb the reading
will make sense.

Lou
--
Posted by news://news.nb.nu

 

[none]

Lou Holtman wrote:
> They can be accurate but there will be a delay. You just measure
> altitude gain and distance travelled. In a long even climb the reading
> will make sense.

Hrm...it's my understanding that the altimeters on these units are
usually not terribly. Wouldn't a current grade measurement require a
very high level of precision?

Thanks,
-Mike

 

[none]

Lou Holtman wrote:
> They can be accurate but there will be a delay. You just measure
> altitude gain and distance travelled. In a long even climb the reading
> will make sense.

Hrm...it's my understanding that the altimeters on these units are
usually not terribly accurate. Wouldn't a current grade measurement
require a very high level of precision?

-Mike

 

[Lou Holtman]

none wrote:
> Lou Holtman wrote:
>
>> They can be accurate but there will be a delay. You just measure
>> altitude gain and distance travelled. In a long even climb the reading
>> will make sense.
>
>
> Hrm...it's my understanding that the altimeters on these units are
> usually not terribly.

That's correct since it is a relative measuement.

Wouldn't a current grade measurement require a
> very high level of precision?

There is not such thing as a 'current grade'. The grade displayed is the
grade over the LAST x meters, and x varies between the cycling
computers. It's a running average.

Lou
--
Posted by news://news.nb.nu

 

[Mike A Schwab]

>There is not such thing as a 'current grade'. The grade displayed is the
>grade over the LAST x meters, and x varies between the cycling
>computers. It's a running average.

Here is a current grade bicycle handlebar mounted inclinemeter, just
like a carpenter's level:
http://circlecitybicycles.com/inclin.htm

There might be some that use a mercury filled curved tube similar to a
thermostat.

 

[Zoom]

Mike A Schwab wrote:
>>There is not such thing as a 'current grade'. The grade displayed is the
>>grade over the LAST x meters, and x varies between the cycling
>>computers. It's a running average.
>
>
> Here is a current grade bicycle handlebar mounted inclinemeter, just
> like a carpenter's level:
> http://circlecitybicycles.com/inclin.htm
>
> There might be some that use a mercury filled curved tube similar to a
> thermostat.
>

Nobody in their right mind should buy anything with mercury in it.

Zoom

 

[Olaf]

On Fri, 02 Sep 2005 21:44:23 +0000, none wrote:

> Lou Holtman wrote:
> > They can be accurate but there will be a delay. You just measure
>> altitude gain and distance travelled. In a long even climb the reading
>> will make sense.
>
> Hrm...it's my understanding that the altimeters on these units are
> usually not terribly accurate. Wouldn't a current grade measurement
> require a very high level of precision?

My cyclecomputer (VDO MC1.0) uses the distance and altitude difference of
the last 12 seconds to calculate the grade measurement. Let's say you ride
50 meters in 12 seconds (thats about 15km/h). A grade of 6% means a
elevation of 3.0 meters per 50 meters. A grade of 7% equals 3.5 m per 50m
and 8% equals 4.0m per 50 meters. Just from looking at the altimeter
reading on the display (and a short comparisson with a GPS) I suspect the
altitude error to be a few meters. (That is assumed the weather has not
changed, but it usually won't over 50 meters.) So I don't except the grade
readout to be very accurate. On my prevision mountainbike-trip my computer
thought the maximum grade I rode was 29%! ;-)

Olaf

 

[Kenny]

"Here is a current grade bicycle handlebar mounted inclinemeter, just
like a carpenter's level:
http://circlecitybicycles.com/ inclin.htm"

Sorry, to say this but it only measures up to 21% grades. I'd like one
that would at least go to 40%. : )

 

[Larry Coon]

none wrote:

> Hrm...it's my understanding that the altimeters on these units are
> usually not terribly accurate. Wouldn't a current grade measurement
> require a very high level of precision?

I've checked my readings (Ciclosport HAC-4) against my GPS
and it's pretty accurate -- usually within 1%. As others
have said, the longer & more consistent the slope the better.
On my lunchtime ride there's a little hill that's about 11%,
but it's short -- it takes about 25 pedal strokes to climb
it. My altimiter just starts to show a gradient by the time
I'm at the top.


Larry Coon
University of California