cycle cumputer results
Mark Cleary
accurate. I would have thought it not as accurate as my Garmin 305
Forerunner that I simply use for running and biking but wanted something
on the bike all the time.
Today I did a 27 mile ride and went over some already measure courses
and I started the Garmin 305 at the same time. After 27 miles they both
were almost identical. The Garmin had 27.01 and the 8I 27.00 that is
what I call close. I was surprised but the cool thing is the cycle
computer will stop when you have to stop but the Garmin still keeps time
going unless you stop it. They both showed the same average speed of
18.2 mph, the Incite had my max top speed at 30.1 mph the garmin had it
at 29.5 mph.
I have always thought the Gramin required I get at least a certain
amount of time at the speed before it registered top speed. It always
seem like I had to go at least 8-10 seconds at the given speed before it
would call it the top speed.I am guessing the cycle computer will not
need this to establish top speed. I just did not put a lot of faith in
those cycle computers and just shows you how stupid I am, not mention
lacking in faith. I assumed those Satellite computers just had to be
more accurate since they involved "space age" technology.
Glad I did not rely on the instructions that came with it they were
worthless. I just played with it enough to figure out the process.
--
Deacon Mark Cleary
Epiphany Roman Catholic Church
thirty-six
> Well have two rides under my belt with the trek Incite 8i and it is dead
> accurate. I would have thought it not as accurate as my Garmin 305
> Forerunner that I simply use for running and biking but wanted something
> on the bike all the time.
>
> Today I did a 27 mile ride and went over some already measure courses
> and I started the Garmin 305 at the same time. After 27 miles they both
> were almost identical. The Garmin had 27.01 and the 8I 27.00 that is
> what I call close. I was surprised but the cool thing is the cycle
> computer will stop when you have to stop but the Garmin still keeps time
> going unless you stop it. They both showed the same average speed of
> 18.2 mph, the Incite had my max top speed at 30.1 mph the garmin had it
> at 29.5 mph.
That's decided, I'll never pay full price for a garmin, load of junk
if you ask me, cant even give you your correct speed. But if you'r5e
giving one away, send it this way.
Ben C
> Well have two rides under my belt with the trek Incite 8i and it is dead
> accurate. I would have thought it not as accurate as my Garmin 305
> Forerunner that I simply use for running and biking but wanted something
> on the bike all the time.
>
> Today I did a 27 mile ride and went over some already measure courses
> and I started the Garmin 305 at the same time. After 27 miles they both
> were almost identical. The Garmin had 27.01 and the 8I 27.00 that is
> what I call close. I was surprised but the cool thing is the cycle
> computer will stop when you have to stop but the Garmin still keeps time
> going unless you stop it. They both showed the same average speed of
> 18.2 mph, the Incite had my max top speed at 30.1 mph the garmin had it
> at 29.5 mph.
>
> I have always thought the Gramin required I get at least a certain
> amount of time at the speed before it registered top speed.
Probably right because it works by measuring your position every second
or so (you can make it more or less often in the menus somewhere). So
unless you hold that top speed for about a second it will miss it.
> It always seem like I had to go at least 8-10 seconds at the given
> speed before it would call it the top speed.I am guessing the cycle
> computer will not need this to establish top speed.
I should think its max speed would be based on the fastest single wheel
revolution, and at 30mph you're doing about 6 wheel revolutions per
second.
> I just did not put a lot of faith in those cycle computers and just
> shows you how stupid I am, not mention lacking in faith. I assumed
> those Satellite computers just had to be more accurate since they
> involved "space age" technology.
They may give you a slightly shorter distance than the wheel computer
since they are giving you the total length of the straight lines joining
the sample points.
Also, they don't seem to be as good at measuring elevation as they are
latitude and longitude. Don't know why that is, but it may mean that
over a hilly course there's a bigger error in the mileage.
thirty-six
>
> I should think its max speed would be based on the fastest single wheel
> revolution, and at 30mph you're doing about 6 wheel revolutions per
> second.
>
probably updates every 1/2 second.
> > I just did not put a lot of faith in those cycle computers and just
> > shows you how stupid I am, not mention lacking in faith. I assumed
> > those Satellite computers just had to be more accurate since they
> > involved "space age" technology.
>
> They may give you a slightly shorter distance than the wheel computer
> since they are giving you the total length of the straight lines joining
> the sample points.
>
> Also, they don't seem to be as good at measuring elevation as they are
> latitude and longitude. Don't know why that is, but it may mean that
> over a hilly course there's a bigger error in the mileage.
If you can set your rollout to millimetre accuracy on the rollout then
I think that the electronic milometre is as good as a pace stick.
DirtRoadie
> Also, they don't seem to be as good at measuring elevation as they are
> latitude and longitude. Don't know why that is, but it may mean that
> over a hilly course there's a bigger error in the mileage.
Nope, not relevant in that regard. GPS measures distance strictly by
planar latitude/longitude position, just as you get by measuring on
map. Elevation plays no part. However a wheel-based cyclometer does
measure the actual "surface" distance covered.
DR
thirty-six
ISTR that the military spec gave height co-ordinates as well down to
100mm.
Tom Kunich
"thirty-six" <thirt...@live.co.uk> wrote in message
news:b3b46dd8-cafd-40a3...@z34g2000vbl.googlegroups.com...
mike
@z4g2000prh.googlegroups.com>, DirtR...@aol.com says...
position is approximately 1.5 times as great as the error in horizontal
position. So if horizontal position is to +/- 12-18 m then vertical
position should be accurate to 18-27 m. It is worth noting that, due to
the irregular oblate spheroid shape of the earth, there may be an extra
'error' term in vertical position depending on the accuracy of the GPS'
model of the shape of the earths surface. So it is possible to be at th
ecoast and have a reading out by 30-40 m, but the relative change in
altitude should still be in the 20-20 m accuracy range. I think that it
is only because a typical ride might cover 30-60 km in the horizontal
direction and only 1-2 km in the vertical direction (in a really hilly
place) that the vertical resolution _appears_ to be so much worse than
the horizontal resolution of a GPS.
Mike
Tom Kunich
news:wsidna7ijqoEVUHX...@earthlink.com...
Wonder how that got posted. I must have hit something that did that but I
didn't see it.
Tom Kunich
news:MPG.2547927ec...@news.comnet.net.nz...
>
> GPS 'measures' latitude, longitude and altitude. The error in vertical
> position is approximately 1.5 times as great as the error in horizontal
> position. So if horizontal position is to +/- 12-18 m then vertical
> position should be accurate to 18-27 m. It is worth noting that, due to
> the irregular oblate spheroid shape of the earth, there may be an extra
> 'error' term in vertical position depending on the accuracy of the GPS'
> model of the shape of the earths surface. So it is possible to be at the
> coast and have a reading out by 30-40 m, but the relative change in
> altitude should still be in the 20-20 m accuracy range. I think that it
> is only because a typical ride might cover 30-60 km in the horizontal
> direction and only 1-2 km in the vertical direction (in a really hilly
> place) that the vertical resolution _appears_ to be so much worse than
> the horizontal resolution of a GPS.
The vertical resolution is much cruder since most of the satellites being
used do not have a good angle and hence the errors are a whole lot more than
they claim. Mileage is particularly bad if you have a lot of moderate
rollers.
Ben C
> On Oct 19, 9:52�am, Ben C <spams...@spam.eggs> wrote:
>
>> Also, they don't seem to be as good at measuring elevation as they are
>> latitude and longitude. Don't know why that is, but it may mean that
>> over a hilly course there's a bigger error in the mileage.
>
> Nope, not relevant in that regard. GPS measures distance strictly by
> planar latitude/longitude position, just as you get by measuring on
> map.
Didn't realize they did that.
> Elevation plays no part. However a wheel-based cyclometer does measure
> the actual "surface" distance covered.
Yes, so that would explain differences in the readings where you're
going up and down hills.
Tom Kunich
>
> The vertical resolution is much cruder since most of the satellites being
> used do not have a good angle and hence the errors are a whole lot more
> than they claim. Mileage is particularly bad if you have a lot of moderate
> rollers.
Let me expand on this:
I measure my wheel diameter roll-out under load and then check it with the
highway mileage markers. I'm almost exactly on over distances though I've
noted that the highway markers can be off perhaps a half a tenth between
markers over short distances.
This last weekend I rode with a group and we put in 160 miles over the
weekend and all of us were within a half mile of each other. The two GPS
guys had 2 and 3 mile differences. Another guy I ride with has two GPS's
mounted on his bike and sometimes carries another in his rear pocket. They
almost never match with any high accuracy.
thirty-six
> "Tom Kunich" <tkun...@earthlink.net> wrote in message
Fit a trailing wheel, with a wooden draw bar centrally loaded with
sand, with a solid rubber tyre and an old matex mileometer. Whoose
gonna question that?
Mark Cleary
computer was exactly the same. The only difference was I had a top speed
of 33.9 mph on the computer and the GPS had me at 32.5 mph.
I don't know about other GPS devices but my garmin is dead accurate. I
use it running everyday. I have a 7 mile course I run and it is never
off by more than .03.
Tom Kunich
news:hbik1l$se9$1...@news.eternal-september.org...
> Tom Kunich wrote:
>>
>> I measure my wheel diameter roll-out under load and then check it with
>> the highway mileage markers. I'm almost exactly on over distances though
>> I've noted that the highway markers can be off perhaps a half a tenth
>> between markers over short distances.
>>
>> This last weekend I rode with a group and we put in 160 miles over the
>> weekend and all of us were within a half mile of each other. The two GPS
>> guys had 2 and 3 mile differences. Another guy I ride with has two GPS's
>> mounted on his bike and sometimes carries another in his rear pocket.
>> They almost never match with any high accuracy.
>>
> Well today on a 34 mile ride my GPS measure 34 miles and the cycle
> computer was exactly the same. The only difference was I had a top speed
> of 33.9 mph on the computer and the GPS had me at 32.5 mph.
>
> I don't know about other GPS devices but my garmin is dead accurate. I use
> it running everyday. I have a 7 mile course I run and it is never off by
> more than .03.
Let me expand on this a little - the San Francisco bay area is rather hilly
and these errors only show up on routes with significant climbing. On flat
ground I haven't seen significant errors.
Mark Cleary
> Mark Cleary <mcle...@comcast.net> considered Mon, 19 Oct 2009
> 16:00:11 -0500 the perfect time to write:
>
>> Tom Kunich wrote:
>>> "Tom Kunich" <tku...@earthlink.net> wrote in message
>>> news:8rSdnaN48KUZUUHX...@earthlink.com...
>>>> The vertical resolution is much cruder since most of the satellites
>>>> being used do not have a good angle and hence the errors are a whole
>>>> lot more than they claim. Mileage is particularly bad if you have a
>>>> lot of moderate rollers.
>>> Let me expand on this:
>>>
>>> I measure my wheel diameter roll-out under load and then check it with
>>> the highway mileage markers. I'm almost exactly on over distances though
>>> I've noted that the highway markers can be off perhaps a half a tenth
>>> between markers over short distances.
>>>
>>> This last weekend I rode with a group and we put in 160 miles over the
>>> weekend and all of us were within a half mile of each other. The two GPS
>>> guys had 2 and 3 mile differences. Another guy I ride with has two GPS's
>>> mounted on his bike and sometimes carries another in his rear pocket.
>>> They almost never match with any high accuracy.
>>>
>> Well today on a 34 mile ride my GPS measure 34 miles and the cycle
>> computer was exactly the same. The only difference was I had a top speed
>> of 33.9 mph on the computer and the GPS had me at 32.5 mph.
>>
> The GPS is measuring map mileage, where the cycle computer is
> measuring road mileage. The GPS may well compensate for that using
> it's altitude measurement, but that is at a lower accuracy, and is in
> any case a lower resolution - it's data points are further apart.
>
>> I don't know about other GPS devices but my garmin is dead accurate. I
>> use it running everyday. I have a 7 mile course I run and it is never
>> off by more than .03.
good 2 mile run on smooth pavement slight downhill and a good tailwind.
I manage to stay over 30 for longer than I ever have I am pretty sure. I
would to try those mountains where they have big downhills. I here those
talking about going 40-50mph and I don't think I have the guts to do
that. Problem is you have to go up them too.
Tom Kunich
> They are not too many hills around here but yes you are correct. I had a
> good 2 mile run on smooth pavement slight downhill and a good tailwind. I
> manage to stay over 30 for longer than I ever have I am pretty sure. I
> would to try those mountains where they have big downhills. I here those
> talking about going 40-50mph and I don't think I have the guts to do that.
> Problem is you have to go up them too.
Do NOT go down hills faster than you feel comfortable. If you become too
frightened you can freeze at the controls or do something really dumb. As
you gain more experience with downhills you gain more confidence and
generally do the correct things at the correct time.
There are those fearless people who dived off of steep mountains before they
had good control over their bikes. Since you USUALLY do the correct thing
automatically most of the slowly developed the proper responses because they
had small problems that they corrected over time. Unfortunately back when I
used to work on Centuries I'd have to call the ambulance for those who tried
going faster than their experience allowed.
thirty-six
> "Mark Cleary" <mclear...@comcast.net> wrote in message
>
> news:hbiq16$gg4$1...@news.eternal-september.org...
>
> > They are not too many hills around here but yes you are correct. I had a
> > good 2 mile run on smooth pavement slight downhill and a good tailwind. I
> > manage to stay over 30 for longer than I ever have I am pretty sure. I
> > would to try those mountains where they have big downhills. I here those
> > talking about going 40-50mph and I don't think I have the guts to do that.
> > Problem is you have to go up them too.
>
> Do NOT go down hills faster than you feel comfortable. If you become too
> frightened you can freeze at the controls or do something really dumb. As
> you gain more experience with downhills you gain more confidence and
> generally do the correct things at the correct time.
If you're not comfortable, you're not employing the best technique.
Find the problem and address it. A slight change in front tyre
pressure or riding position may make an otherwise difficult descent,
simple. Pushing your limits until you feel uncomfortable identifies
what are otherwise imperceptible errors in riding or the mechanics of
the vehicle. It is useful to push your limits, as the otherwise
imperceptible faults become subconciously accepted. Follow a faster
cyclist (of known experience) and learn from his movements.
>
> There are those fearless people who dived off of steep mountains before they
> had good control over their bikes. Since you USUALLY do the correct thing
> automatically most of the slowly developed the proper responses because they
> had small problems that they corrected over time. Unfortunately back when I
> used to work on Centuries I'd have to call the ambulance for those who tried
> going faster than their experience allowed.
If you ever feel yourself running out of road, you went into the
corner too fast or, more likely, you took the wrong line. Early turn-
ins are the number one cause of running out of road. Should have
mentioned earlier, use the full road width and camber both sides when
it is safe.
RonSonic
>"Mark Cleary" <mcle...@comcast.net> wrote in message
>news:hbiq16$gg4$1...@news.eternal-september.org...
>> They are not too many hills around here but yes you are correct. I had a
>> good 2 mile run on smooth pavement slight downhill and a good tailwind. I
>> manage to stay over 30 for longer than I ever have I am pretty sure. I
>> would to try those mountains where they have big downhills. I here those
>> talking about going 40-50mph and I don't think I have the guts to do that.
>> Problem is you have to go up them too.
>
>Do NOT go down hills faster than you feel comfortable. If you become too
>frightened you can freeze at the controls or do something really dumb. As
>you gain more experience with downhills you gain more confidence and
>generally do the correct things at the correct time.
Ahh, that moment of Zen when you realize that unless and until you unclench,
that speed wobble will only get worse. Then you ask yourself if there's any
assurance that unclenching will actually fix it and realize the answer is no.
Then the magical point where you become too terrified to not relax. It's either
that or vector off the road, rigid, oscillating and screaming like a little
girl.
--
Oh damn. There's that annoying blog. Again. http://dumbbikeblog.blogspot.com
thirty-six
> Ahh, that moment of Zen when you realize that unless and until you unclench,
> that speed wobble will only get worse. Then you ask yourself if there's any
> assurance that unclenching will actually fix it and realize the answer is no.
> Then the magical point where you become too terrified to not relax. It's either
> that or vector off the road, rigid, oscillating and screaming like a little
> girl.
>
Just be a man and admit you're too fat for your wheels. Inadequate
wheel stiffness is the primary cause of speed wobble.
DirtRoadie
> Let me expand on this a little - the San Francisco bay area is rather hilly
> and these errors only show up on routes with significant climbing. On flat
> ground I haven't seen significant errors.
"Error" may not be the correct term. It is true that a wheel-based
cyclometer measures the surface distance while GPS measures the
"bird's eye view" - the same thing you would measure on a map.
But even if you did a ride on a steady 8% grade (just as an arbitrary
figure) for 100 miles (as measured by the cyclometer), the GPS would
measure 99.7 miles. No error, just a different measurement.
But if you are riding in very hilly terrain the GPS also has a greater
opportunity to have dropouts in reception and those sometimes add up
to a greater discrepancy, in that case, an error. Such errors can be
seen on a display of a GPS tracklog (using mapping software) as large
obvious glitches. Sometimes merely deleting the errant point(s) gets
the track back into conformity with actual values.
For the most part, GPS is amazingly accurate.
DR
DirtRoadie
> In article <f634575a-093e-4ea7-a7c0-9d474ef9d2c5
>
> > > Also, they don't seem to be as good at measuring elevation as they are
> > > latitude and longitude. Don't know why that is, but it may mean that
> > > over a hilly course there's a bigger error in the mileage.
>
> > Nope, not relevant in that regard. GPS measures distance strictly by
> > planar latitude/longitude position, just as you get by measuring on
> > map. Elevation plays no part. However a wheel-based cyclometer does
> > measure the actual "surface" distance covered.
>
> GPS 'measures' latitude, longitude and altitude.
True, but GPS does NOT use the altitude data in determining distances.
It works just the same as if you were using a map.
For example, if you are trying to navigate to a location, you enter
the coordinates as lat/lon - no elevation.
Same thing whether you are doing that manually or using mapping
software that lets you click to mark a spot on a map. It's still just
considering two dimensions.
There is no more "error" is GPS distances than there is in distances
determined by using a nice flat paper map. It is not the same as slope
distance but it is EXTREMELY close for any terrain likely to be
navigated by bicycle. And, in fact, it is the slope distance (as
measured by a cyclometer) that should probably be considered
inaccurate.
DR
Michael Press
<bf2e8e8d-42d5-4ff8...@i12g2000prg.googlegroups.com>,
DirtRoadie <DirtR...@aol.com> wrote:
> On Oct 19, 3:19 pm, "Tom Kunich" <tkun...@earthlink.net> wrote:
>
> > Let me expand on this a little - the San Francisco bay area is rather hilly
> > and these errors only show up on routes with significant climbing. On flat
> > ground I haven't seen significant errors.
>
> "Error" may not be the correct term. It is true that a wheel-based
> cyclometer measures the surface distance while GPS measures the
> "bird's eye view" - the same thing you would measure on a map.
> But even if you did a ride on a steady 8% grade (just as an arbitrary
> figure) for 100 miles (as measured by the cyclometer), the GPS would
> measure 99.7 miles. No error, just a different measurement.
GPS error can be any direction from the actual position.
That means it will plot a polygonal path that wanders
about the actual path of the bicycle. Based on this,
one expects GPS to over estimate the distance travelled.
So, yes error.
> But if you are riding in very hilly terrain the GPS also has a greater
> opportunity to have dropouts in reception and those sometimes add up
> to a greater discrepancy, in that case, an error. Such errors can be
> seen on a display of a GPS tracklog (using mapping software) as large
> obvious glitches. Sometimes merely deleting the errant point(s) gets
> the track back into conformity with actual values.
>
> For the most part, GPS is amazingly accurate.
--
Michael Press
DirtRoadie
> GPS error can be any direction from the actual position.
> That means it will plot a polygonal path that wanders
> about the actual path of the bicycle. Based on this,
> one expects GPS to over estimate the distance travelled.
> So, yes error.
You missed the point entirely. If you measure slope distance (as with
a cyclometer) you get a figure which is different from horizontal
distance as measured with a GPS device. There is no "error", it's two
different measurements which would be expected to be different.
I then described what DOES constitute "error" and you have merely
echoed that in different words. So we partially agree.
DR