My research on Speedometers and GPS

**bombhills114** · 07-13-2008 10:20 PM

Originally Posted by mrpauliepants

What was it built with?

idk.. like a circuit board, and a small computer w/ gps attached.. he wrote the code and stuff

at the end of the run it tells you your max speed that time down as well

**BenBanned** · 07-14-2008 12:44 AM

He talked about it in the post.

How about a helmet mount?
Can anyone think of an aero friendly way without comprimising the safety of the helmet to mount?

**mrpauliepants** · 07-14-2008 12:52 AM

Originally Posted by jkpvilla

has anyone tried using cyclocomputers?

Aren't those the same as bicycle speedometer? I was looking at those today at the store, they have to use mounted sensors around the tire, which is an issue when you're talking about longboard wheels.

Originally Posted by BenBanned

He talked about it in the post.

How about a helmet mount?
Can anyone think of an aero friendly way without compromising the safety of the helmet to mount?

Mmm... Only thing I could think, would be to mod a helmet so it has a tail on it (kinda like the Charly helmets) with that tail being an addition to the helmet, wherein the gps is somehow mounted inside that space. That leaves the question of direct site to sky, though if it uses some sort of antennae, you could leave that through, pointed skyward.

In theory.

**lollygag** · 07-24-2008 01:15 PM

for a GPS to accurately measure speed it must have a 1/per second continuous refresh/update rate..

In the case of navigation and logging GPS products, that sample rate is especially important. A Navigation product needs to take a sample at least every few seconds to accurately locate the receiver and provide correct navigation. However, in tracker (logging) products, they need to take a sample reading every second to accurately measure speed. Location, and travel direction are easy, but accurate speed measurements require more precise sample readings from the GPS satellites. A one second sample can accurately measure speed to +/- 1 MPH/1KPH, but some trackers take a sample only every 6-20 seconds which can induce significant error.

most $100-200 GPS's wont measure speed accurately.

**d-dub** · 08-13-2008 09:12 PM

**Basch** · 08-13-2008 11:18 PM

1 Navman A300 mounted on front foot. You can put it so you can read you current speed from tuck (at least when goofy). Awsome little device

**shapeshifter** · 08-14-2008 12:31 AM

i picked up a few of the garmin 530 hcx... these are frs/gmrs two way radio communication devices with built in gps (having only one would be pointless). when you have a dialogue between two or more of these units they basically show up on your map so autolocation is the key purpose. it has a waterproof rating that's pretty low but better than most (it can get wet, just not to deep or wavy). great compass and trip computer, you'll not only know speed, direction, duration of movement and stops, virtical drop and rate of said drop, and way tmi. your radio has multi band communications (technically you should be licensed to use gmrs btw) and multiband weather.

now the best part is the gps with it's map displays. topo is your terrain info, city navigator gives you street and turn by turn directions, bluechart provides soundings and bathymetric charts of underwater features such as reefs and shouls... and there's more. the maps come at a price though and with this product it can get expensive. but like everything else, nothing is safe from a cleaver hack.

so what's the purpose of all this... using your topo you find the steepest roads in the area and check it against citynav for intersections and such... set your spotters who can contact you even if it is a long winding hill and you do not have a visual. take your run and record your track data (ie: speed, direction, gradient, etc) using the trip computer. along comes the man and you have to split... using the radios you know the exact location of the others especially if you have to disperse. another purpose is for finding the surf... weather radio lets you know the small craft advisories, bluechart gives you the underwater terrain to find the features that would offer potential for wave formation given the right weather pattern. using the radio you can do your soundings to catalogue these potential surf spots. get the picture?

**hop2x94** · 08-14-2008 08:46 PM

i wish i had a gps

**Zach337** · 08-16-2008 05:38 AM

I just scored a navman s300 for $55 shipped! Should be here on thursday, I'm stoked.

**hesevoli** · 08-17-2008 01:20 AM

check out the Venom Speed Meter for r/c cars, it costs about $30, runs on 4 AA and is pretty accurate, as it works by counting revolutions. You just install a magnet in one of the wheels, a sensor, and then set your final drive ratio (1:1 for skating) and wheel diameter. Has the same kind of functions, average speed, distance, top speed, etc.

**Gearfire** · 09-06-2008 05:11 AM

Originally Posted by BenBanned

He talked about it in the post.

How about a helmet mount?
Can anyone think of an aero friendly way without comprimising the safety of the helmet to mount?

SportVue MC1

I found this a few years ago.
I'm reading the manual PDF, and it looks like it uses a magnet on the wheel to determine speed and a 2nd computer module that is put somewhere on the bike. There is supposed to be a bicycle model, SportVue BC1, which may be easier to mod though I can't find crap about it.

There is a Skydiving model using GPS being released soon. Looks perfect, and expensive.

They say they do custom development services.
I'll shoot an email at them for some advice.

**backwoodsboarder** · 11-24-2008 11:47 AM

on the suunto watches the x10 has gps and my dad has one for hunting and marking his routes because you can download all your stuff to Google earth. And when it comes to on watch features its fairly stripped down to way points and just track logging.

**chandler95** · 11-25-2008 04:55 PM

Does anyone have any info on how to mount the forerunner 201 onto your shoe? I've tried searching but had no luck.

Cheers!

**dak** · 11-26-2008 05:00 AM

DON'T WAST MONEY
gps systems do not make you ride faster !!!!!!!!
try judging how close you come to the edge of the road !
gps readouts are not worth 1 cent when it comes to race day ,size of nut's does !
your feeding to much information to yourself to make the right race decision !
if it scares you your going fast ! instinct is faster than data .

**Arsin225** · 12-08-2008 05:51 PM

Originally Posted by hesevoli

check out the Venom Speed Meter for r/c cars, it costs about $30, runs on 4 AA and is pretty accurate, as it works by counting revolutions. You just install a magnet in one of the wheels, a sensor, and then set your final drive ratio (1:1 for skating) and wheel diameter. Has the same kind of functions, average speed, distance, top speed, etc.

I was going to make my own based on the same thing but then I learned that it's not that accurate you got to take into consideration...

Wheel not touching pavement (Maybe it hit a rock and flew up a bit)
Inner wheel going slower then outer or vise versa (Turning)

Even GPS's aren't that accurate they just use V=d/t disregarding all other factors.

The best speedometer is your brain, just bring out a calculator, pencil or pen, and tons of paper.

**wooden** · 12-13-2008 09:58 PM

Originally Posted by dak

DON'T WAST MONEY
gps systems do not make you ride faster !!!!!!!!
try judging how close you come to the edge of the road !
gps readouts are not worth 1 cent when it comes to race day ,size of nut's does !
your feeding to much information to yourself to make the right race decision !
if it scares you your going fast ! instinct is faster than data .

it's not a question of being a better rider/racer/whatever, it's wanting to know how fast you're going. knowing your speed doesn't make you a better rider or change race outcomes, but you can't deny that you'd like to know your speed in most longboarding situations.

a note on garmins: i've been working at REI for a little over a year and the eTrex has a lot of signal issues; can't find enough satellites, trees getting in the way, etc. the forerunner is really the way to go if you want a wristwatch style gps. even though they can be off by 5 mph in either direction, you at least have an idea of your speed. better than nothing, imo.

**chrismcb** · 12-13-2008 11:17 PM

Originally Posted by wooden

it's not a question of being a better rider/racer/whatever, it's wanting to know how fast you're going. knowing your speed doesn't make you a better rider or change race outcomes, but you can't deny that you'd like to know your speed in most longboarding situations.

a note on garmins: i've been working at REI for a little over a year and the eTrex has a lot of signal issues; can't find enough satellites, trees getting in the way, etc. the forerunner is really the way to go if you want a wristwatch style gps. even though they can be off by 5 mph in either direction, you at least have an idea of your speed. better than nothing, imo.

In a straight line, on a level surface the forerunner is accurate. We used these on the Salt Flats on powered luges. Up to 150 mph they agreed with the timing systems used.

The problem is GPS isn't very accurate with elevations. This is where any inaccuracies will come in. Of course it should be consistent from run to run.

**Clemson_Fan** · 12-24-2008 12:25 AM

What are current GPS speed tolerances for low,mid,and high end price ranges?
And in case it matters we will say at 50mph.

**jaxxstatic** · 12-24-2008 06:36 AM

Siegrist updated his site. Anyone know what GPS he, Mischo, and others use that Martin made a sleeve for? The sleeve attaches to your front shoe. I'd really like to get one and see about how fast the roads in Okinawa are. The GPS I use right now is one of the handheld ones, and it's really cumbersome to hold and bring it up to look at it.