Fairings for commuting

Discussion in 'Commuting and Road Safety' started by Grant-53, Oct 1, 2012.

  1. Grant-53

    Grant-53 New Member

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    For years I have been experimenting with fairings on upright bikes and found they give me a boost in speed on the order of 4 mph. I mount them to the frame rather than the handlebars and have no trouble with crosswinds. For some reason most people assume fairings are not useful until I show them how one works. Then they ask if I plan to patent my fairing. If you use a fairing please share photos and your experiences.
     
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  2. maydog

    maydog Well-Known Member

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    Are you seriously using the faring shown in your profile pic? If so, I have several questions.

    How fast do you average when using the faring?

    Are cross winds a problem, how about rain?

    To me it seems that such a device would not be good for commuting. It obstructs the view immediately in front of you. It looks to make steering limited as well. Obstacles such as debris, pedestrians and small animals would be hard to avoid. Wind would make steering difficult. The faring itself would prevent you from getting low so your head will always be sticking out. Plus it may attract a lot of unwanted attention, it may lead drivers to target fixation.

    In a crash the results may not be pretty, is that a large skewer I see holding up the bottom of the front cone?

    Have you instead considered using aerobars and/or an aero helmet? How about a recumbent, the aero benefits are much greater with or without farings.
     
  3. Grant-53

    Grant-53 New Member

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    This fairing was built in 2006 and allowed me to cruise comfortably improving my speed from 10 mph to 14 mph as I am an older rider. The bike as pictured has areobars set 10 in. apart. Since the shape is a cone and attached to the frame, I have had NO trouble with crosswinds even in stiff winds. This is the problem with most fairings on the market or in the patent files - they attach to the handlebars and forks ahead of the steering axis. The material is plastic and waterproof, covering the shoulders, arms, and thighs. I use either a rain jacket and chaps or a LeMond rain suit depending on the length of trip.
    The view forward is quite adequate as the nose tapers to a 4 in. diameter at the 6v PAR-36 headlamp. There is enough room for steering while riding and the aluminum support arm does not go all the way to the front. The wire mesh would absorb energy in a crash and the arm is easily made of two pieces with shear bolts or plastic fasteners to avoid the skewer effects. The design for commuting is to have full vision left, right, and a rear view mirror. A face shield is in the works for the next version and the tail box will be higher.
    A recumbent is heavier and has the same drag as an upright on aerobars. My basement stairs would not allow a LWB recumbent to make the turns. In short, well designed fairings can be safe and effective.
     
  4. Volnix

    Volnix Well-Known Member

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    Hmmm, they would look nice if the commute was in Neverland from the magic tree to the rainbow falls but really I am not using that anywhere near people... /img/vbsmilies/smilies/biggrin.gif
     
  5. Grant-53

    Grant-53 New Member

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    I have a more conventional motorcycle style piece that gets similar results. People complain about headwinds and rain but this is the simplest solution I have seen in decades. Hey, if you want to paint purple ponies on yours that's up to you. All kidding aside, this practice of reducing aero drag means the speed differential in urban traffic is greatly reduced. A younger cyclist would have little trouble going 25-30 mph and the visual impact makes a cyclist more substantial looking. I have not been harrassed by irate motorists when riding with a fairing nor have I noticed any "target fixation". Maybe the fact that we have a high tech helicopter plant in the area has accustomed people to streamlined shapes. Bottom line is that the side wind issue has successfully been mastered and there are real gains to be had from a device a 12 yr old can put together in an afternoon. Log a couple hundred miles with a fairing before you try to tell me it can't work!
     
  6. maydog

    maydog Well-Known Member

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    Farings are cool when done right and used in the right applications.

    Aerodynamic drag at those speeds is pretty low (20% of your total?). I bet the actual benefit of having these farings is due to changing the way you ride or mental / placebo boost. At 10mph, you are better off to tackle rolling resistance.

    Any obstruction to your forward field of view is a problem, most cyclists like to ride around hazards - not through them. Without a serious redesign, I not would advocate that anyone use such a setup out on the streets. Its a neat science project, maybe - but not practical.
     
  7. Grant-53

    Grant-53 New Member

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    Look at the technical literature and you will get a surprise. Aero drag is much greater than rolling resistance. I use a cyclometer to record speed data and do coast down tests to eliminate rider input. I repeat that the tapered nose cone is not a problem for the sight line anymore than a front handle bar bag. I don't have a problem with wheel placement or running through trash. If you don't see an object until you're 3 feet away, do you have enough reaction time to avoid it? A newer design that lets me see the front tire is just as effective and even easier to build. I've done the math and done the road work including city traffic. Maybe some different pictures will help make the point. Commuter riding is where a fairing will have the most improvement for the most people. We just need to get over the future shock and deal with the issues realistically. More to come.
     
  8. alienator

    alienator Well-Known Member

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    Unfortunately, cost downs and a cyclometer aren't sufficient to pull out aerodynamic data. You need to be able to also quantify slope and wind. I think most people here are aware of how drag varies with velocity (as the square of the velocity) and how rolling resistance varies with velocity (linearly with velocity). Certainly cross winds are a concern with fairings, and just mounting the fairing to the frame does not null the effect of crosswinds. I'll bet a number of people on this forum have dealt with gusty mountain winds on descents that have pushed us across our lanes. Likewise, one downside to time trial frames and aero road frames (different than TT frames) is their handling in crosswinds. Heck, anyone who's piloted a sport bike (motorcycle) on a windy enough day can vouch for the effect of cross winds on the large, presented area of the fairing sides. Simply put if the center of pressure (from the crosswind) isn't coincident with the CG of the bike rider system, it will introduce a moment about the CG, and if that moment is large enough, it will impact handling. Keep us apprised of what your work. Experimenting is fun.
     
  9. Volnix

    Volnix Well-Known Member

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    lololol /img/vbsmilies/smilies/biggrin.gif
     
  10. Grant-53

    Grant-53 New Member

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    [​IMG]

    To put your minds at ease, I have worked as a mechanical engineering technician for a number of years. I grew up around gliders and sailplanes so I have a thorough understanding of aerodynamics and fluid mechanics. I pictured an older fairing design to gauge consumer responses. All the issues you all have been so kind to mention have been dealt with in detail. The result is a simpler front fairing for commuters made from a single piece of 4mm coroplast quarter sheet (24" x 48"). A number of correspondents from ecomodder.com and recumbents.com including Vetter Challenge competitors have been building motorcycle and upright bicycles with efficient fairings.
    [​IMG]
     
  11. Grant-53

    Grant-53 New Member

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    [​IMG]

    This is the latest version and it works very well. I use the hill at the end of my street for coast down tests. It is sheltered from winds and I use the same distance each time. Yes, any vehicle is going register some input from crosswinds and I test all fairings in windy conditions. The difference is between 'barely noticeable' to 'unmanageable' steering input when the fairing is mounted to the frame rather than handle bars or forks. This frame has fairly neutral steering geometry so I don't use full aero bars or heavy front panniers. My education included fluid mechanics and mechanical engineering courses. Stability is improved when the center of mass is ahead of the center of pressure. We are fortunate here to have the Glenn Curtiss Museum and the National Sairplane Museum nearby for examples of streamlined forms. The WISIL and IHPVA articles are available at recumbents.com and many great pictures can be found by using Google Images searching for "upright bicycle fairings".
     
  12. wphamilton

    wphamilton New Member

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    Kindred spirit here, and I'd like to encourage you in experimenting and improving your designs.

    I've commuted the past three winters using a faired upright, and let me say that all the standard objections that have been brought up in this thread can be overcome.
    [​IMG]


    I'd average about 20-22 mph with this one above

    [​IMG]
     
  13. Grant-53

    Grant-53 New Member

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    Thank you for the pictures. Do you have any pics of the side and tail? You can follow another discussion at recmbents.com/ technical/ upright.
     
  14. pinkride

    pinkride New Member

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    Does that really improve your speed per 4 mph? If that is true then that's awesome! Ok, it does look a bit awkward, but the additional speed is always welcome.
     
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