I built an inexpensive fairing out of coroplast for my m5 lowracer recumbent bicycle. This page has some pictures of the fairing while under construction and has some advice that I hope someone finds useful. Let me know if it was of value to you. email to rjd@merit.edu and tell me of your successes (and failures).

First, start with the bare bike Consider where you want to attach cross brace members. I put one between the front wheel and the frame, and another underneath the frame directly behind the seat. Sit on the bike and make measurements at your shoulders to determine how wide the bike needs to be. Also make measurements to determine how much room you need for your feet to clear the fairing at all points in the revolution of the crank arms.

Make the fairing as narrow as possible! Don't worry about making it just a little too narrow since the coroplast and brace material will give a little. Ideally, you want to have to actually push the fairing material out of the way with your shoulders. However, it is annoying having your feet brush against the fairing, so design in at least 1-2 centimeters clearance by your feet.

The trickiest part of building a fairing this way is building it without bumps and buldges. To prevent this, draw an outline of the support members and make a jig. Nail a bunch of nails into a piece of plywood you placed the drawing you made on. I use PVC tubing for the support members. It is flexible enough to allow some 'give' when you hit potholes and sections can be attached together using plumbing fittings and special glue. It can be bent using a heat gun; heat small sections and use a jig or it won't turn out right.

I built a front boom to attach the fairing to. I cut a plumbing tee in half and clamped it to the bottom bracket using radiator hose clamps. I then attached a section of tubing to that and drilled a hole near the end to pass the other tube through. You'll probably need to extend the tubing with some plumbing fittings. Glue in a cross brace using a plumbing tee. You might also need to apply the heat gun to the cross brace so that it's square to both plumbing tees. I just used cable ties to secure the cross brace to the bike.

Now use aluminum clothes line wire and make some more supports. I used wire rope clamps to secure the ends of the aluminum wire to make a hoop. I didn't use a jig to make the hoops and later wished I had. Drill a hole in the PVC tubing and pass the wire through it. Don't worry if everything seems like it flops around too much; the structure will become stiffer when the skin is attached. Now cut the first strip and attach it to the supports. I used small cable ties to attach the coroplast. Pierce two holes a little less than a centimeter apart through the holes so that the aluminum wire runs between and run a cable tie through the holes and around the wire.

By the way, use 2mm coroplast. Most coroplast is 4mm. The 4mm will work, but it is more difficult to work with and weighs more. It is also more difficult to bend. The 2mm can be hard to find, but it's worth the effort. In the yellow pages, look under plastics. The 2mm is also known as "fine flute" coroplast. I found that a scissors works well for cutting the stuff. Use a permanent ink pen or a grease pen to mark where you want to cut. Unless you have someone who can do atlas' job handy, hang the bike from your ceiling using wires. This saves a lot of wear and tear on your back!

Now add a whole BUNCH of thin coroplast strips to the frame work to make the front. Cut the ends so that they're flush with the other pieces and use adhesive backed tape (like that used to reinforce and seal cardboard boxes) on the outside to attach the strips together. The more strips you have on the front the more closely it will resemble a curved surface.

Here's a picture from the driver's seat of the partially completed front fairing.

If you need to make the fairing wider or narrower, modify the first strip that you attached so that you can maintain symmetry. Now that the front is done, trim all the front fairing pieces so that it will be easy to add a flat piece for the sides and bottom. The flat sections go quickly since you don't have to do much trimming to make the edges of the flat sections flush with other pieces.

Now finish up the back. I was in a hurry so I didn't spend a lot of time making it look good. The rear of the bike isn't as aerodynamically important as the front, so if you're going to cut corners, cut them on the back.

Trim all the ends of the cable ties and add the odd piece of tape here and there and you'll be ready for a test ride! Be careful when first taking it out. Resist the urge to bomb down the first hill you come to. Find a bumpy road and give it -literally- a shakedown cruise to see if anything falls off or loosens up and starts rubbing the wheel or pedals. Re-do any cable ties that scrape you or you'll wind up looking like you tried to force feed a cat some medicine it didn't want to take. Make sure you can safely steer and brake. Figure out how you'll get into and out of the contraption you just made without somebody's assistance.

Naturally I ignored my own advice the first time out. I was going down a hill at around 40 mph (65 kph) when part of my fairing decided to get friendly with the spokes in the rear wheel. A small piece had folded over and made quite a racket, which caused some exciting moments while I quickly came to a stop. After I stopped I (at first) couldn't figure out how to exit! I managed to get out without resorting to falling over first at least. You should also probably bring along a few tools in case you need to make some adjustments.

After building the fairing I also discovered that I couldn't see over the top of it as well as I had hoped. I decided to modify the fairing so that I could see through it. I had a large Zzipper fairing on my Tour Easy that had seen better days and was ready for retirement anyways, so I put it on the M5. It is very easy to modify the fairing after the fact to make these types of changes. I used the stock mounting holes at the bottom of the fairing and merely bolted it to the coroplast. I used tape to attach the edge to the coroplast.

I still want to do some more work on the fairing. I'd like to use some stretch fabric to cover the hole where the front wheel is. I'd also like to clean up the back of the fairing a bit and make some sort of top so that the bike can be fully enclosed. I think it will have to wait until spring 1997, though. Check this page then for updates!

I didn't weigh the fairing, but I suspect it weighs about 8 pounds (4 kg). It increases my time-trial-on-level-ground speed from about 23 to 29 mph (37 to 46 kph). It really rockets downhills; I can get it going 35 mph (56 kph) down modest hills very easily. The fairing was made to meet the requirements for the modified class of the HPV races I go to and so was not optomized for street use. None the less, the bicycle is still (barely) streetable. Cross winds are not a problem because the fairing gives a little when hit by sideways gusts. It will get pushed around a bit but this is not a problem until I'm going over 25 mph (40 kph) and the winds are gusting over 25 mph (40 kph). I do have problems at stop lights because the fairing restricts my foot and so makes releasing from my clipless pedals more difficult. It also makes it more difficult for me to put my hand down on the ground (the prefered method on a low-racer). A door could easily be built to eliminate the latter problem and I'll probably add one at a later date.

References:
Zzip designs bicycle fairings home page
Coroplast home page.
Bill Volk's Coroplast Faring and Fun Page


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