speedometer inaccuracy

S

Smallwheels

Guest
Go Digital

The digital bicycle speedometers are more accurate than any car speedometer if you calibrate them properly. My speedometer cost about $13.00 on sale at www.bikenashbar.com. They have different sales all the time so visit there often.

The calibration process for this one was to just measure the distance of one full rotation of the wheel and enter the number in millimeters into the computer.

GPS is not always accurate. It's good enough for dropping bombs on a particular location but not for measuring speed. Missiles do just fine with GPS because they just travel in straight lines above the ground. If one uses GPS to calculate speed the road must be perfectly flat, and straight as an arrow, otherwise any extra distance due to curves is not considered.
 


S

Stryker

Guest
GPS is not always accurate. It's good enough for dropping bombs on a particular location but not for measuring speed. Missiles do just fine with GPS because they just travel in straight lines above the ground. If one uses GPS to calculate speed the road must be perfectly flat, and straight as an arrow, otherwise any extra distance due to curves is not considered.

I am not sure if you understand GPS, The small Garmin 305 Cycling unit I use not only accurate to give or take 15 meters on your lat long, it also can give you your 3D location meaning Altitude. This all on GPS alone, most GPS also have internal barometers, for back up altitude, and WAAS that brings the accuracy to 3 meters. This you might not know is more accurate than the southwest 737 you fly on, which is not WAAS capable, (older technology). It will tell you exactly how fast you are going. But it will cost you.
Oh and after i am done with my ride I down load it to motion base .com and replay my ride on an overlay google map. Speed, climb gradient, ect... and I can go back on my next ride and race myself.
Soon I am going to see if I can beat my last ride using the boost bottle.
 
K

kenspice

Guest
Gps

The digital bicycle speedometers are more accurate than any car speedometer if you calibrate them properly. My speedometer cost about $13.00 on sale at www.bikenashbar.com. They have different sales all the time so visit there often.

The calibration process for this one was to just measure the distance of one full rotation of the wheel and enter the number in millimeters into the computer.

GPS is not always accurate. It's good enough for dropping bombs on a particular location but not for measuring speed. Missiles do just fine with GPS because they just travel in straight lines above the ground. If one uses GPS to calculate speed the road must be perfectly flat, and straight as an arrow, otherwise any extra distance due to curves is not considered.

Hey Small Wheels,
I have a Garmin60csx GPS. Put that name in your browser and look it up. You may get quite a surprise about the latest technology. As in the previous post, you will pay for it. You can buy it on sale now for about $275.00.
With the new chip and all the goodies I always have 7 or 8 satalites locked in. They will update every .5 seconds and is probably as accurate as the cop's radar. I use mine for hunting and bicycling. They now run for 18 hours or more on 2 AA batteries. It keeps a record of every trip I do on it and my downloads to the computer. I used it on a trip to Hawaii and Japan and have a record on a map that goes right down to street address numbers of every foot of the way. Get one as they make biking and traveling MUCH more fun.
Ken
 

LabRat63

New Member
Joined
Feb 3, 2008
Messages
25
I'm looking at possibly getting a Boost cell phone with a built in GPS. Anyone tried them or similar?
 

Watcher05

Member
Joined
Jan 14, 2008
Messages
38
GPS's are accurate for speed!! The satalites have atomic clocks in them to operate correctly. I have what would be called one of the 'cheaper' portable ones around and I can be assured that I can find my little tiny crab traps everytime. Trilateration is what they use and have to be very accurate for them to work. Read: http://electronics.howstuffworks.com/gps.htm

:D
 
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L

Large Filipino

Guest
I got a cable speedometer. That needle sways here and there and lately hasn't worked at all but most important to me is the odometer. I took my bike on a highway just to calibrate my odometer staying far far away from other cars to the right I probably would have been stopped anyway and rode between two mile markers. I just went from one marker to the next one which is exactly supposedly 1/10th of a mile and my odometer read spot on.Then I walked off the highway.
It's plastic inside with the needle looking pretty weak but the odometer part is geared so as long as the speedometer cable is turning my odometer is working.
I never liked the electronic speedometer for I went on a long run with it one time and it didn't read. Then you can reset that odometer.
I like a solid way of knowing how many miles you've traveled on your beloved. Then you can think about all those miles.
Speed well I have one of those radar signs a block away.
I already know what my top speed is.And I'll never go there again.
I know my cruising speed is about 18 mph. Way under the get in trouble range.
I say if you have to look at your speedometer,your going too fast.
 
J

JacksonCognac

Guest
yeah I had one of those mechanical speedos on my bike. It was a total POS and I eventually took it off because I didn't like the look of it. I've stripped my bike down to the bare essentials and it looks a lot cooler.
 

kawasaki999

Member
Joined
Jan 18, 2008
Messages
335
gps

Here is the ticket.
 

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