I don't have the numbers with me (maybe someone else knows them, or knows where they can be found?), but higher and higher percentages of a cyclist's energy go into overcoming air resistance as speeds increase. I've seen charts for this, and it is dramatic. Especially at higher speeds, the limiting factor -- and the factor that is really slowing you down -- is air.

One reason fairings are not more often seen or used is that they were outlawed long ago (for many sorts of races), because of their clear advantages.

But commuters are not necessary 'beneficiaries' or recipients of these policies -- most commuters are perfectly free to use fairings if they choose.

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Does anyone know of sources or plans for fairings?, especially fairings for DF bikes?

(Partial fairings seem the most practical, but some full fairing designs might also be worth a look?)

Dig the drops

Don't have any solutions on your fairing problem, but the equations I've seen are that air resistance for bikers increases with the square of the speed at slower speeds and the cube of the speed at faster speeds. This is dramatically unsatisfactory, as it doesn't define fast vs. slow, and is discontinuous. Nevertheless, that's the rule of thumb. I just got a copy of Bicycling Science, and surely somewhere in there is the true equation :-). I'll let you know when I find it.

Best,
Ari

Theres a guy on my commute on a road bike with a big plexiglass fairing. I cruise by him at nearly twice his speed each time.

I also pass a guy on a faired folder many mornings. I can't tell how much he's using the fairing for aerodynamics vs protecting his suit and tie, though.

It's so flippinn windy here lately that all I need is someting to act as a sail. What happens with those faired bikes in a big crosswind gust?

A common error when discussing aerodynamics is that most people don't realize its how you leave the air, rather than how you meet it. i.e. that teardrop finish you see on some streamliners.
The other thing is, you have to minimize cross sectional area as well as reducing the friction co-efficient.
This is one of the reasons recumbents are faster on the flat. See this pic.
https://www.recumbentblog.com/images/frontal.jpg
Recumbents are often easier to mount fairings to.
A very simple change you can make is going to race style clothing, if your jacket is flapping, its wasting energy. I know one downhill section of my commute has a 2-4 kph difference if I'm wearing a flappy jacket.

That too ... but some folk are not willing or able to wear spandex "(I do)

Why on earth not?

Sometimes is not convenient for some folk (not me ... I am a luky spandex clad lad), sometimes ... mmm ... they know they rather not ... harrassement (happens to me, but I pity the imbecile that gives me a hard time) , and many other reasons.

Spandex is wonderful and i wear unpadded sometimes, even at home.

I also saw recently, somewhere around here, a recumbent w/ an aero ... trunk type thing behind the seat, a wedge-shaped framework, that was pretty cool. Should have definitely done something to keep the air flow laminar, not turbulent, behind the rider.

Random points....
--Full HARD fairings on two-wheel bikes are extremely difficult to handle in crosswinds; most people experienced with them feel that such devices are NOT useful for a bicycle used on the street--just because of the crosswind danger (-a "hard" fairing is one made of essentially rigid material-).

--The two "main" recumbent fairing companies are Zzipper and Windwrap. Both companies products offer roughly comparable products, and both will sell the bits and pieces separately if you're doing a D.I.Y. job. These are polycarbonate plastic sheeting heated in ovens and blown. ....You see on the Zzipper home page, a fairing for the RANS Zenetic, which is a semi-recumbent. Some of these fairings could probably be fit onto upright bikes the same way.

--What many recumbent riders do to cut wind drag is use a front fairing (from Zzipper or Windwrap) and then use a body sock. A special rear rack is attached to the bike, and a lycra sleeve is stretched between the edges of the front fairing and the rear rack. Although these look kinda silly, they can have almost as low drag as a hard fairing, and have some "give" so they're not so dangerous in crosswinds. They are also lightweight, and relatively cheap and easy to make if you've already got the front fairing.

--Front fairings do cut drag, typical is they ad 1 to 1.5 mph onto a 16-18 mph cruising speed but they also add weight. People do use them in hot climates, but it seems like most people who buy them do so partly because they live and ride in cold weather, and using a front fairing drastically cuts wind chill that the rider feels.

--Regarding tailboxes, there's a few upper-end companies that offer them for their bikes (recumbents costing $3000-$4000+) but a lot of people make them out of corrugated plastic (often used for cheap small signs). Search Google or Google images for the terms "recumbent coroplast", and you'll get pages of people who have done home-made fairings. Some look cheap and silly, some look impressive, most are in-between.

--It is true that drag happens behind objects and not in front of them--but even so--informal experiments generally show that adding a FRONT fairing helps more than adding just a tailbox. The one exception to this is that lowracer recumbents (like the Velokraft NoCom) generally aren't fitted with front fairings, because for the fairing to be effective the rider's body must be placed relatively close to it, and with the stretched-out designs of lowracers this isn't possible--so such bikes like the Optima Baron (another lowracer) are commonly seen fitted with tailboxes, but rarely ever are used with front fairings.
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I don't wear spandex/lycra because I don't have Brad Pitt Abs.

ive got great abs "a 8 pack even" just cant see it under all the belly fat

I have read this too. Friction, which is where weight comes into effect, is a linear function. Air resistance is a cube function of the air speed. Apparently cyclists should be more concerned about aerodynamics than weight, especially if you ride in the wind a lot like I do.

I was thinking the same thing about a year or two ago. I came across a thread (can't remember which forum) where a guy who tried a partial fairing claimed it only gained him about an extra 1 mph. I figured it wasn't worth it for only 1 mph.

The most practical way for better aerodynamics seems to be reducing your frontal area. Which workingbike's picture illustrates.

When I go back to recumbents I'll just use the tail box. I had a full rigid fairing once and got into serious heat stress problems twice during a California spring tour. I'll accept the reduced efficiency if it means I stay cool.

I converted workingbike's picture to a silhouette where maybe it's esier to see the differences in frontal area.

Thanks to both for these pictures -- they are good ones.

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How much difference would it make to have a good rear fairing (or tailbox) to clean up the air flow? (I know it would depend on a variety of factors, but I would still be interested to find out -- both for uprights and for recumbents.)

You could try a highracer recumbent. The rider position is more aerodynamic overall, and the general effort required to ride is considerably lower as well (it takes considerable effort to balance on a bicycle saddle, but you don't know that until you ride a bicycle that doesn't require it).

Particularly I'm thinking of the RANS Force 5 Enduro, because it's got 26" wheels and enough frame room for moderatly fat tires (comes with 1.95's) and costs only around $1500. The Bachetta and Volae bikes are possibilities too, though most of them have frames that lack room for anything but skinny road-bike tires. If suspension is your desire then there's bikes like the Grasshopper, but the prices go north quickly.

Most of the drag on a bicycle is from the rider themselves--so the greatest practical advantage to be gained is to switch to a bike that has a better rider-aero position--and that is comfortable enough to use that position all the time. Aerobars are nifty for TT's but you can't stare at your axle when you're dancing with cars--and holding your head up is h3ll on yer neck.
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