How do YOU measure your speed?

B

broloch

1 kW
Joined
May 10, 2008
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What is your method for speed measurement?

Are you a GPS'er, or a cycling computer user?

Do you have a friend ride next to you who has a computer?

Do you light a candle, and pray to some higher being ... lol wtf?
 
I use a cycling computer 90% of the time for basic trip data. I use a Garmin Etrex Vista GPS for the remaining rides when I need more developed data such as time moving vs time stopped, elevation gain, glide ratio calcs (grades), and of course directions/maps.

Higher Power? You bet I always ask God for protection before I ride around Boston.

Bill
 
I did a roll out measurement to set my Cycle Analyst speedometer. It's the direct plug-in model so gets its readings through the hall sensor signals from the motor controller.
 
I use:

- my C-A (calibrated with my Garmin GPS)
-My Garmin GPS
-My Belltronic FX2 accelerometer performance computer ( Wheel power, max speed, G-forces, 1/4 mile time)

Doc
 
Cheap cycle computer, the book calibrations are bogus, so I calibrate by using mile markers on the highway. Accurate to about 50 feet per mile.
 
stand-alone cycle analyst with the spoke magnet. Fairly reliable. Sometimes, I have to move the wires around because the sensor goes dead :?
 
I just use the doppler effect... estimate the pitch of the object in front of me, then again when it wizzes past me as I goose the throttle :)
 
How do I measure it? I prefer not to. Otherwise, in the DB I stretched out a tape measure and measured two loaded tire roll outs from valvestem to valvestem, then devided by two. For the rest I prefer to not have a speedometer. They look bad, weigh something and don't seem to be useful. It's pertty easy to guesstimate how far you can go and how fast getting there.
 
I have speedo/cycle computer and the gps on my phone which picks up about 12 satellites. Its pretty accuracte. My cycle computer is accurate as far as distance so i know its accurate on speed. I ride on a trail with mile markers and its dead on. Found out my car is 6 mph slower than the speedo. Also if you pay attention. When you ride your bike with the controller hooked up but no battery power the back emf from the motor will go back into the controller and the controller will leak current back into my Watts Up Meter. Depending on how fast you are going you get a voltage reading thats pretty damn close to the speed that you are going. Atleast on my bike it does. Its about 2-3 mph off. The faster you go the less accurate it is but its good up to about 15-20 mph. Another useless fact. Has anyone else experience this?
 
I use gps for topspeed runs and adjust wheel dia on cycle analist to get it close but it only gives ballpark, radar is more accurate but not practical. If your cheap you can buy a gps do a topspeed run on your vehicles and return it the same day lol. If you calibrate the cycle analist using a gps it is pretty close.
 
icecube wrote:
Depending on how fast you are going you get a voltage reading thats pretty damn close to the speed that you are going.
Click to expand...
When I first set up some plug braking for my WE BD36 in a 26" wheel I used 12V headlight bulbs. In order not to blow them, I temporarily wired in an old analog volt meter and observed the voltage produced was very close to the speed ($7 Bell Bike Computer).

I don't care about the accuracy too much, but I do like a good estimate. The same Bell computer is currently on my trike, and I think it died in the rain a couple of weeks ago. It still turns on when the trike moves, but does not register the speed. It was several years old and I'll probably get another one like it next time I get out to civilization.

My recumbent bike has the computer on it that the original owner installed in 2002. I know it's not accurate, since my tire is a little larger than the original. But I can't figure out how to change it, the model is out of production, and I can't find instructions that work, and I think it may have some issues. When it dies I plan to try a wireless one.
 
Rassy said:
. . .
My recumbent bike has the computer on it that the original owner installed in 2002. I know it's not accurate, since my tire is a little larger than the original. But I can't figure out how to change it, the model is out of production, and I can't find instructions that work, and I think it may have some issues. When it dies I plan to try a wireless one.
Click to expand...
Have you looked at this page?
http://www.sheldonbrown.com/cyclecomputer-calibration.html

I'd not trust a wireless one anywhere near an electric motor.
 
EMF coming off the motor cause some weird back ground noise that get inducted into the signal wire and mess up the signal transfer also caused background wireless noise. I had my BD36 at 60v that cause some serious noise on my car radio when i rode by. I could put a speedo on my BD36 it works sometimes other times it didnt. I tried wired and wireless. On my GM the wired one worked the first time out the box.
 
Zoot Katz wrote:
Have you looked at this page?
http://www.sheldonbrown.com/cyclecomputer-calibration.html

I'd not trust a wireless one anywhere near an electric motor.
Click to expand...
Thanks ZK. I had gone to the "Cateye" web site before and did not find this model. The instructions on Sheldon Brown's site (Bless his soul, I've used lots of his guides) were very detailed and specific. And better yet, it works. :D

You are probably right about wireless. Since I'll be 70 on my next birthday this one will probably outlast me anyway.
 
Used to pedal bike rollers indoors to train for cross country stamania biking. I know an 80rpm cadence like a marathoner knows their efficiency pace. Cross reference that with my gearing info. and Sheldon Brown's (God rest his soul) gear calculater and botta botta bing! High gear is spot on 20mph or 19 to 21mph :? next gear down is 17-18mph, then 15mph, so on. The church bus is lousy as they gave me almost 30mph when it was 24mph; a 90 cadance is when the bike starts bouncing good :p
 
These $3 (shipped!) speedometers are surprisingly accurate. I've compared it to a few devices and it's never off by more than 0.5mph

Plus if it gets stolen off the bike you won't freak out.
Plus it's ugly looking so it doesn't look valuable.

If you order one, remember it will take at least 15 days to show up.
 
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