A Practical HPV and recumbent bike Fairing
A Practical(and inexpensive)HPV fairing
By Warren Beauchamp
Winter 1998
Riding in the Midwest is always exciting. You can never tell from one week to the other what the weather will be like. And to top it all off, from mid October to around May, you can bet it will be unpleasant (yes, there are better words to describe it...). Because I would like to be able to stay in shape during the nasty bits of weather, and life on the trainer can get somewhat monotonous, I decided to build a fairing for my ATP Vision R-40 ASS HPV Bentmobile. Ed Gin had given a seminar at a WISIL meeting about a year ago, and showed us how he had constructed an inexpensive fairing out of Coroplast (that plastic sheeting that looks like corrugated cardboard). This seemed like the best bet. In the past year Ed discovered that a non-Coroplast nose cone was more aerodynamic, and began using one that he purchased from Rick Wianecke (who has been cranking out one or two very nice fiberglass nosecones with mounting brackets every month or so). As we have been experimenting with blowing large plastic bubbles, I decided to make my nosecone out of Vivak. We had made bubbles out of various thicknesses and it seems that anything under about 60 mils is too thin, and tends to deform under stress (like that of breaking the wind at 35 MPH!)

Vivak is available at your local plastic supply house, and costs about $28 for a 4'x8' sheet. I used a 2'x4' section to make my bubble. To form it you first need a rather large oven, which can heat up to a uniform 250 F. You then make a flat template of whatever shape you want the outer edge of your bubble to be out of 3/8" or thicker plywood. See the How to make blown HPV fairings page for more information. Once everything is in place, and the oven is up to the proper temperature. Air pressure is applied behind the flat sheet of plastic, and it balloons outward. Once the proper shape is attained, the oven door is opened (while maintaining the shape with small spurts of air) and the bubble cools. Remove it from the form, trim the flanges and Wala! Instant fairing!(comparatively speaking)

Coroplast is also available at your local plastic supply house, and costs about $10 for a 4'x8' sheet. I used two for this project.

Basic Construction technique involves cutting the Coroplast with a knife, and then attaching the separate Coroplast parts with plastic wire ties. Support bracketry and reinforcements are attached with pop-rivets. The Vivak nosecone is attached to the Coroplast body with pop rivets. You can cover the seams with electrical tape for a more uniform look (If you can find tape to match your Coroplast). See Russel Dwarshuis Coroplast fairing page for info on building Coroplast nosecones.
 

You can make good mounting brackets from PVC pipe, which has been hose-clamped to your bike frame. This photo shows the "top" bracket mounting. Don't glue the tube into the "T" as you will want to be able to remove the fairing. I put some self-stick foam padding under the hose-clamps on the bottom of the tube to prevent the tube from getting scratched up. I also added a removable pin to fasten the tube to the modified "T" bracket to prevent the tube from bouncing out of the "T" when encountering large bumps.
This photo shows the front mounting bracket. You may have to trim the hoseclamp to get everything to clear properly. Ed Gin uses a metal "T" bracket here due to multiple failures of the PVC one. I haven't had that problem yet. The PVC pipe is just stuck into the bracket. It stays in without a problem.
This shows the front boom, which is attached to another PVC "T". This PVC "T" is attached to a bent 1/8"x1" piece of aluminum strap, and the nosecone bubble with pop rivets. The Coroplast is also attached to the nosecone with pop rivets. Be sure to use pop rivet washers as a backing when pop riveting through Coroplast. This boom gets lots of bouncing motion. I ended up using large wire-ties to fasten the "T" to the aluminum strap/vivak bubble, as the aluminum pop rivets failed. Ed Gin says steel pop rivets work better than aluminum ones here.
The photo below shows how the top boom is mounted to the sides of the fairing. The PVC tubing is all glued together using stinky PVC cement. Once again, pop rivets were used, through the nosecone, and Coroplast, into the PVC "T". In the background you can see the PVC mounting holding the tailcone on, as well as another aluminum strap which keeps the rounded contour of the top of the fairing stable.

The PVC pipes in that back of the fairing are attached to the seat tubes with large wire-ties.

Note that if you use this method to mount a windshield without the rest of the body, your front mounting bracketry will have to be a lot stronger. The rigidity of the Coroplast body prevents a lot of the motion that causes fatigue in nose-cone only or non-rigid body applications. I recently found that the top PVC "T" is not strong enough for cold weather use (gets brittle), as it failed on a bumpy road on a 20F day. On warmer days it had no problems. I made a new spiffy aluminum top boom which has held up much better (not pictured).

Here's the other side with the door open. The door is held on with with small hinges to make it easy to open and close. The back of the door is held in place with Velcro. Note: make the door lower than I did, it is a real contortionist act to get in and out.

Here's what the bike looked like on the road shortly after I built it. I added another chunk of plastic between the windshield and my head to keep me warmer and to improve aerodynamics. With this extra part on I can't reach outside the bike to close the door, so it hangs open a little. I'll have to work on that one... This picture was before I remodeled the tail to raise it to the height of my shoulders.  Thanks to my neighbor Norm for the photo...
3/28/1998
I decided that the footwell was a rather large hole, and that closing it in would help the aerodynamics considerably. As I really do need to put my feet down on occasion, it needed to be something that would move out of the way when I slam my feet down it an emergency. I decided on Spandex. I found a remnant of black Spandex at the local cloth shop ($0.90), and sewed some Velcro onto it to hold it in place. I also reinforced some of the weak points in the Spandex. I used the stick-on Velcro on the fairing side of things. My wife was nice enough to let me use her sewing machine for this little project. The Spandex fills in the entire footwell, except for a slot for the wheel. I just push the material out of the way when I put my feet down. No picture, I took one, but all you can see is a black hole in the bottom of the bike.  In testing (63 mile ride) I found that it does not cause any problems. As far as speed increases go it's hard to tell...
1/15/1999
Here's a shot of the "completed" fairing. Note that the fairing comes apart in a front and back section, which are held together by Velcro. The windshield and the lower faired area are parts of previously rejected bubbles. The seams have been covered with yellow electrical tape to provide slightly better aerodynamics, and better looks. Wheel covers should help the aerodynamics and looks as well. The photo shows the tail section modifications. I modified it to be the same height as my shoulders. Bill Murphy and I built an aluminum T bracket to replace the PVC one that breaks when riding in sub 30 degree temperatures I also painted the outside of the blown nose screaming zonker yellow to match the Coroplast.
pfairing14.jpg (8447 bytes)
pfairing10.jpg (5820 bytes) In order to transport the fairing, as I have a "compact" car, it was necessary to construct it so that it would come apart in two sections. It was also necessary to make them nest together (one half fits inside the othe). This picture shows the two halves, which are held together with Velcro (that's that white stripe in the middle of the fairing).
Here are the two halves, separated. pfairing11.jpg (6572 bytes)
pfairing12.jpg (7713 bytes) Here are the two halves, nested together.
The fairing just barely fits in the back of my Corolla, and the bike itself fits on a bike rack which rests on the rear window of the car. The rack pictured was made by Enflite, who was purchased by or changed their name to Draftmaster. The rack is now called "SportFlite". pfairing13.jpg (11771 bytes)
practical99.jpg (7970 bytes) 11/01/1999
This shows the final incarnation of the practical fairing, after I made a modification to the lower rear of the fairing to improve aerodynamics. Picture taken by Wendy Toy. This is the last shot of the fairing mounted on the ATP Vision R40. It will be reincarnated onto the new Street Barracuda in the spring of 2000.

Conclusions:
The Fairing weighs about 10 pounds, on top of a 30 pound bike. It has increased the average speed on my short in-suburb training runs by about 15-20%! It has increased top speeds to 40MPH+ (mild downhill).

Total costs -   $79 (for revision "A")
2 - sheets of screaming yellow Coroplast at $20 each
1/2 of a 4x8 sheet Vivak (2 nosecones, 1 mis-formed) - $14
2 bags of small wire ties - $2
1 bag of large wire ties - $2
1 bag PVC "T"s for $2
1 - 10ft chunk of 1" OD PVC pipe - $1
2 - 2" to 1.5" PVC "T" adapter - $3
2 - 1.5" to 1" adapter - $1
3 - 4' sections of 1/8"x1" aluminum strap - $9
1 box of 100 "long" aluminum pop-rivets - $5
1 box of 100 "medium" aluminum pop rivets - $5
3 boxes of 20 aluminum back up washers - $3
4 hose clamps - $4
Roll of self-stick Velcro - $8

Total time -
I didn't really record the time... I'd estimate about 30-35 hours total build time to complete the original fairing, and then a lot more time tinkering around with it.

Blatherings -
I recently rode a metric century (The "Chili" ride) with the new fairing and finished the 72 miles in about 4 hours. I rode a number of extra miles because I missed some turns (It's hard to see dark red markings on the side of the road at 25mph!). The most fun part about it was blowing by the roadies who were all drafting each other. Nobody passed me. The wind picked up about half way through the ride, and I found that though riding in a stiff side wind at 25 to 30mph can get interesting, I was able to stay safely in control by leaning into the wind. Strong gusts on the other hand were scary at first, but you get used to them. Uphill climbs seemed to be unaffected by the extra weight and I was able to pass roadies going up the hills too. Who says recumbents can't climb? I did find that the bumps are a lot worse at 25 to 30mph than they felt at 20 to 25mph, especially on a (very)short wheelbase bike like my ATP Vision.

I rode a 20 mile loop in the country, on a very windy day, and averaged 22mph. Cool.

This fairing was trashed after I sold the ATP Vision in 2000.

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