Developing the Cape Cod Sail Bike

by Tom Leach

HARWICH, MA - (02/05/05) Since I was a kid, I have hung onto a copy of the November 1967 National Geographic Magazine which featured a story about dry-land sailors (three wheelers) that crossed the Sahara Desert. I have ice boated, windsurfed and sailed but always wanted to build one of these Sahara sand sailers. I guess this wind bike somehow fills that nitche for me. I surfed the web and wondered why I found only one or two references to the sail bicycle (wind powered bike) concept.

This is something that has crossed my mind many times. Finally Super Bowl weekend I decided to build my first wind-powered bicycle utilizing an old beach cruiser type bike (the kind that has balloon tires and safety brakes) that was given to me by a neighbor. The gem here is that I was able to take the sailing system from a Cape Cod Frosty (TM) and quickly adapted the mast support tube and and boom to the rear of the bike frame with about a half dozen inexpensive U-bolt clamps. The boom and clew of the sail are controled by a boomkin that is adapted to the bike frame with a tube. The main sheet is brought to the front of the bike via blocks and kept very short so that it can be kept in hand and not let go under the bike and cause and accident. That is why the safety brake under foot is important as handle brakes does not allow a free hand to control the "main sheet".

The ground testing took place at the Hardings Beach parking lot in Chatham, MA and a breezy day with about 10-15 knots steady. The bike easily reached about 20 mph. The cruiser bike with its foot control safety brakes and wide handlebars made controling the eratic "on-off" power of the breeze controlable. I could easily travel in a straight line. An English style bike, a ten speed, or even a mountain bike in this application would prove dangerous!

This was actually great fun and was not as dangerous as I thought it might be. Sailing down the road so quietly it seemed that the bike generated power as it increased speed and the sail was trimmed. The bike was easily tacked and jibed. The bright colored sail was good too as a safety warning to any motorists. The top of the mast is also well under 14' height and clears all wires. The wind bike sets up in under five minutes but avoid using the kick stand lay the sail-bike down on the ground, otherwise it will blow over.

The expectation for this project is not as a toy but it might well provide a totally economic form of transportation for the World as fuel prices climb over $2/gallon here in the US and $5/gallon elsewhere. This may not be fuel cell technology, but it works.

A vang might be a good thing to help keep more power in the sail on a reach (cross wind), but I couldn't figure out how to arrange for it. Another obvious addition would be a wind indicator forward.

The sail used is from a Cape Cod Frosty one-design dinghy. It has 25 square feet of sail area. In a plan showing a sail bike in the Boy Mechanic Magazine from 1911 two sails are suggested of a total of 40 square feet. I found the 25 square foot sail adequate in medium air and required "hiking" or leaning the bike to windward. Too much sail area might prove dangerous.

As a kid, with brothers and friends, we found endless joy in our bicycles which gave us the the freedom to travel miles from home. In those days, it seemed parents encouraged us, and it would be nothing, to bike to school, to stores in the next town, or a distant park to play baseball, and return by late afternoon. It was an age when parents weren't so worried every minute where their kids were and even encouraged them to explore. We took huge pride in our bikes and equipped them with front or saddle baskets and depended upon them more for transportation than the kids novelty that they are today.

Last, month in Costa Rica I spent a lot of time making use of a beach cruiser to get around the village including riding the beach. It was better transportation than the jeep. Now I wonder how the application of sailpower in such a windy place with road-hard beaches could bring an entirely new element to the use of such a bike.

editorial note: Wear a helmet and heavy clothes. Do not try this unless you are a very experienced bike rider and thoroughly understand the power of sail. I've been riding (and sailing) regularly for 45 years. Caution: This is not for children! After riding about 20 minutes the mast broke and the sail fell dragging behind the bike. I think the wood was old and brittle.

(photo credits: Jackie Leach)

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