Simple Dog Repellent
Thu, April 1, 2010 
I never know from one day to the next what interesting email will drop into my inbox. Take for example the one I received a few days ago from a young engineering student from the UK.
Edwin DePrise grew up in Africa, Kenya to be exact, where his father was an animal conservationist. From an early age he discovered that the purpose of a Zebra’s black and white stripes is to confuse a predator like a lion for example that might be chasing it.
Forward to today and Edwin is a cyclist who noticed how dogs will often chase, even attack a cyclist. A dog is a predator and to the canine brain a cyclist gliding silently by might just as well be a deer in flight.
Edwin has developed this simple but ingenious little device that easily clips on the side of a cycling shoe that effectively confuses and deters any dog who gets close enough to bite a cyclist’s ankles.
It consists of a spinning disc inside a clear plastic casing. (See diagram left.)
The disc is divided into six segments colored alternatively black and white. A pair of these clip on the outside edge of either shoe.
The disc is pivoted slightly off center so the pedaling motion causes the disc to spin. This confuses the dog enough that it makes him hesitate or jump back as he goes to bite.
The result is the dog misses his mark and usually ends up getting his nose clipped by the spinning spokes of the rear wheel.
This actually caused Edwin some problems when he was testing the device. He found once the dog had had his nose rapped in such a way it was reluctant to chase again, rendering the dog useless for further testing.
This problem was overcome by fitting the test bike with a solid aero disc wheel on the rear. Some engineer's blue marking dye smeared on the sides of the disc wheel showed up on the dog’s nose, and a hit was recorded.
The idea is still under development. One problem has arisen, namely the left disc spins in a counter-clockwise direction and is effective 91% of times tested; whereas the disc on the right shoe spins clockwise and is effective only 47% of the time. The reason for this is not quite clear.
This makes the device work quite well in the UK where cyclists ride on the left side of the road, and most dog attacks there originate from the left side.
One simple low-tech solution Edwin is considering is a little red knob in the center of the right side disc so a cyclist could manually spin the disc in a counter-clockwise direction, should a dog attack occur.
The device is not yet on the market; Edwin is currently shopping the idea to several manufactures. He expects the price to be very reasonable. He does not have a brand name yet; he refers to it as a Canine Repellent Ankle Protector (CRAP)
Go to http://www.crap.com/ for more info
Reader Comments (8)
Superb.
Awwwww, I was totally sucked in. Not fair, Dave!!
Could it be that in the UK, at least, the dogs are left-brained?
I think Mr Brown would be pleased.
Brilliant!
Damn. Had me right up until the acronym. I think I should just turn in early tonight...
Very nicely done!
You had me as well, up until the end. The funny part was in the beginning I didn't think it made any sense that a dog would react to the spinning wheel in the way described, but as the "data" was laid out I got suckered in.
Stupid "evidence"!
Thanks to all for your comments. This is my 4th "April Fool" post since 2007; it becomes a challenge each year to come up with something different but believable each year. Click on the April Fool tag at the bottom of the piece to read the previous ones. Although probably not so entertaining if you know it's a spoof before hand.
Dave