This is a simple project requiring a minimum of talent and tools and a few readily-available parts. One of the advantages of this type of wind speed indicator is that the rotating cups tend to have a damping effect on the speed readout and you won't see the wild swings in indicated speed so typical of many hand held units. An added advantage is that the cycle computer has many modes; one of which is maximum speed or peak wind gust for the day.
The basis of the device is a bicycle computer (I used an Avocet 40) costing around $40.00. The Avocet uses a non-mechanical sensor system which I prefer over the mechanical sensor (reed relay) of most cycle computers. You'll also need a used bicycle hub (free - $5.00) and some brass strip and sheet available at any hobby/crafi store for under $5.00. The 3 cups are cut from a .016" x 4" x 10" sheet and the arms from a .032" or .064" x 1/2" x 12" strip.
Once the anemometer has been assembled it can be calibrated against a hand held unit or by simply having an assistant hold it out the window of a moving vehicle and comparing the indicated wind speed with the vehicle speedometer. DO NOT try to do the automotive calibration by yourself - you'll be looking at the readout when you should be looking at the road and you'll end up breaking something very expensive. If the reading is off, enter the CALIBRATE mode on the computer and change the calibration number up or down a bit (For what it's worth, with the Avocet I used 195). Sorry, but this process is just trial and error (mostly error) - nobody said this was rocket science.
John Bremner (705) 322-3163 PO Box 312 Wyevale Ontario Canada L0L 2T0 john.bremner@canrem.com
Design stolen from Rusty Ferris - Albuquerque NM