Bike Speedo For Alt Purpose

[Harold in CR]

Hi
I'm in need of a wind speed indicator. A bike Speedometer would work fine, maybe ???

I want to make a 3 legged wind catcher. Think along the lines of 3 half cuts of Ping Pong balls, mounted on 3 wires, radiating from a hub, that is bearing mounted to an vertical axle. There will be a sensor mounted someplace, that senses a magnet that will spin from the PPBalls wind catcher. I'm sure most of y'all know what I'm describing.

Problem I have is, Bike wheels are large and the magnet goes by at a slow rate of speed, compared to what I need.

Any suggestions ??? Buying one is over $150.00 ??? Surely some of you genius types can guide a dummy to make a Bike Speedo work fine ? Anyone ??

 

[Drunkskunk]

make the spinning part have the same diameter as a 20" bike wheel, then use a speedometer ment for recumbants or children's bikes. I think most of the lower priced speedometers will cover a wider range of wheels from 20" to 29".

 

[dogman dan]

Small hand held anemometers have gotten fairly cheap these days. I have one I use for checking wind speeds ballooning, where you want it under 10 mph, and windsurfing, where you want it over 15 mph.

 

[Harold in CR]

I would prefer to have one mounted on the tower of my Wind Turbine, so I can monitor the air flow and get the best location for the tower, and the best height, without overkill.

The bicycle wheel would be overkill, by having a large surface area to control, in high wind conditions.

 

[dogman dan]

Cool. In that case, you could try the flag method. Before the anemometer I used to fly several homemade pennants to judge the wind for windsurfing, and then decide which size sail to use. Made of different fabics, or even the same fabric in different lengths, you can make a pole that tells you wind speeds by which pennant is fully stretched out, and which are only partly flying. The heavy one only stretches out when it blows hard, while the light one takes less wind to fly. Cheap and low tech, it will work fine for you if all you need is to locate the windy spot.

 

[TylerDurden]

Windsocks are standardized, but I think it would be easier to get a cheap wireless weather-station.

For a bike speedo, you might be able to simply calibrate for a small wheel and correct for the offset in your spreadsheet... calibrate with two magnets on the bike wheel @ 180* to simulate a wheel of half the circumference.

 

[Lock]

I really like dogmans idea as simple low-tech, but you could build your own little savonius generator and measure output from that, eg:
http://www.macarthurmusic.com/johnkwilson/MakingasimpleSavoniuswindturbine.htm

Cheers
Lock

 

[dogman dan]

Definitely more than one way to skin a cat. One cool thing about pennants is that they show wind speed, wind direction, and also the quality of the wind. One thing you really really really want is to locate that wind generator in a location that is the most free of turbulence. The linear flow wind is what you want, and an obstruction up to 1/2 mile away can screw up that nice clean wind. A long skinny pennant cut from some nylon cloth works really good for showing the gusts and lulls. Actually any kind of flag works, but I found a pennant about 4 feet long, and 1 foot wide at the pole, and tapering to a point really lets you read the wind.

Surfing in the desert, in really bad gusty sailing wind, you needed to know not just what the wind speed was, but also when to go out. On a given afternoon there might be 1 hour of fantastic sailing in 30-40 mph wind, and the rest of it sucking in 10-50 mph gusts. Watching the flag would tell you when to go out, and not go when the wind was horrible. Ask local sailors about the wind, even if you are inland. They know a lot.

 

[Lock]

...and an obstruction up to 1/2 mile away can screw up that nice clean wind...

On the water, a general rule is that the wind shadow of a boat to windward will extend to leeward about ten times the height of their mast...
Lock

 

[dogman dan]

Yes that is true for obstructions the size and shape of a boat and sail. I garantee you can feel a row of 30 or 40 RV's parked on the shore for at least a half mile downwind. Anybody who's surfed Bird Island in Corpus will agree with that. Or in the case of Southern New Mexico sailing, the lake is in a canyon, and the lowest obstuction to the water is the dam, about 50 feet above the water line. Sailing within 1/2 mile of the dam is very is not so good. We park in a certain spot, and sail a certain area of the lake because when the wind is from the SW, we get great sailing. When it shifts to the west, we start to go back and forth over a much narrower wind slot untill we get far enough out in the lake to go longer. When it is straight west, only the best surfers can get back to the car at all. The rest walk back, since it's so hard to beat into the wind on such a short run. ( we park upwind and always have to sail upwind to get back)

 

[Harold in CR]

OK. Thanks for all the input, guys.

I used to sell and install Wind Turbines and Solar Panels, along with Batteries and other goodies. We bought a GOOD Anemometer and used to set it up in locations for customers to get an idea of what to expect in THEIR locations.

I really can't tell these people that they need 2 streamers and a flag, to get decent wind calculations.

GOOD Anemometers are expensive, compared to Bike Speedos. I figure if I can get a Bike Speedo set up, I can get accurate info. , because the locals here, are asking all kinda of questions. I need to get a readout, of some sort, to be able to relate the actual wind available in THEIR locations. I just don't know how to calibrate the small dia wind cup wheel to get accurate measurements. A Bike wheel is 20"+, so, HOW do I go about calculating a wheel of, say, 8" dia ??

I have a Hydro project started that everyone thinks I'm crazy. I explained it to John the other day, and he thinks I'm nutz, too. What else is new

I don't have a big income, so, I'm trying to get MY place on Alt. Energy, and then see about selling-installing- consulting. Electricity here is NOT cheap and it's rising in price, just like everywhere else. SOME folks realize that in a couple-3 years, costs for basics will ALL be expensive.

Gasoline is well over $4.00 /gallon, so, E-Bikes and E-Motos will come into play, also.

 

[dak664]

I made one with aluminum cups for about $25. You need a really good bearing that can turn in the slightest breeze. I used the spindle from an old hard disk drive which just happened to be the right diameter to press fit into 1 inch PVC pipe. I drilled three holes for the cup spokes and cemented a magnet on the rim. Two magnets might balance better if you expect high winds. One cup over the bearing acts as a rain shield and stiffener, with the three spokes run through holes in it out to the other cups. Epoxy all the joints, put PVC pipe in ground, tape the sensor and speedo mount to the top end, cut the bottom off a PET soda bottle and invert over those so you can reach up from below to attach/remove the speedo, and push the assembled anemometer into the end of the pipe.

The bike computer will show max and average wind speed, total time wind is blowing and number of revolutions. You can calibrate against a known wind speed but I don't know how linear it is, best would be to compare to a real anemometer at several wind speeds. My speeds were quite small, I was more interested in length of time breezes were present at different locations.