Bicycle Teardrop

Teardrop shaped bicycle travel trailers & related information

Aerodynamics 101

Postby angib » Fri May 28, 2004 5:44 pm

(Disclaimer: I am an engineer, but just a well-read amateur on road vehicle aerodynamics - if anyone knows better, please speak up)

Teardrops look aerodynamic, but they're not really - most would probably have lower drag without (yes, without) the rear curve. The rounding of the top-to-front joint is nice, but the squareness of the side-to-front joint is not.

First rule is concentrate on the tail, not the front and, yes, ideally you want the full teardrop shape.

But to give space for your feet inside, you're not going to taper to a point so simply cut the body off square at the relevant point (ref, Dr Kamm, sometime in the 1930s).

Here is a sketch of something reasonably acceptable - but I would love to round off the front corners if I could see a way to do it that wasn't really difficult to build.

Image
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Just bought a used bike trailer

Postby Mike Viger » Mon May 31, 2004 4:28 pm

I was able to pick up a used Bell 2 passenger kids trailer for $75. Aluminum frame, 26" inside measure. 16" bicycle wheels. I found a site that shows how to use electrical cunduit to make a frame. Sounds good.
http://drumbent.com/trailer.html
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Postby Ron Dickey » Tue Jun 08, 2004 12:08 am

Mike,

I have not biked for a long time now gave up about 15 years ago .. but still have my 16 speed mountain bike.

at times I think the bike came before the horse.

If you spend time looking at old National Geographic mags you will see peddlers peddling very heavy things on backs and
fronts of bikes

below are several sits including a search image site offering photo's of all kinds of bike trailers and it would give one an
idea of what is now offered and to be copied .


http://images.google.com/images?hl=en&l ... tnG=Search

below offers different bike trailer mfg.'s and compares them.

http://www.bikeroute.com/WhyTrailer.htm

cab bikes are another example of weight that can be pulled.

www.hiwheel.com/ pedicabs_main.htm

Bikefix is from England and offers different bikes mainly the new low type on 3 or 4 wheels.

www.bikefix.co.uk/ spokesfest.html

Ultimate Bicycle book by Richard Balantine $50

Book offers many pictures of different types of bikes.

might be in Library otherwise a bike shop owner might have one..

it also shows a type of human chain of sit down low bikes offering much more pulling power and rest time in turns.

The human train type could pull a larger trailer and will also depend on the gearing offered on the Bike.

This should help give people an idea of what you can pull with a bike and when you are up to speed it is much easier.

Good luck .... sounds like a healthy project.

Ron D.
Los Osos, CA
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both side walls are up...cabinet needs stain.......ongoing 2.5 yr bld build as i find time..... Cross Bow in Build Journals....viewtopic.php?f=50&t=54108
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Postby Mike Viger » Tue Jun 08, 2004 7:16 pm

Thanks Ron,

Here's one of the companies that sells the Evox 140 that I own.

http://www.triketrails.com/evox.htm

It's 73" long and low to the ground. Great riding comfort, especially with the lumbar support. I don't see building a tear trailer with any great weight. I've been hauling over 100 lbs with the used Bell trailer that I bought and it's been no problem going up steep hills.

I do appreciate the good tips that I've been getting here and you are right about the amount of weight that can be pulled. I've seen cargo trailers here in Ottawa hauling wood planks and furniture! "Green" enviro people.

Thanks for now.
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Postby tdthinker » Wed Jun 09, 2004 10:27 pm

Hey guys, why dont you just get one of those trikes and make it longer( If you can weld) and put your bed compartment on it? The two wheels in the back will give you more traction, be more stable, and be easier to peddle. Just an idea. I will try to get a pic on tomarrow, night
Ryan
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aerodynamics

Postby Mike Viger » Sat Jun 12, 2004 2:55 pm

Angib,

I believe you are right as far as the shape is concerned. Bikes with full body fairings give a good indication of this shape. Bikes with a clear front fairing are contoured (like a Motorcyle windshield). A rear box mounted on behind the passanger is usually square in the front and shaped similiar to your diagram.

In regards to trikes, it seams like a good idea, however they can be on the heavy side. Also are difficult to turn in a tight spot. The bike that I have was selected with the idea of comfort, low and long wheel base. I will be making a clear front fairing too. From what I understand this can add about 15% speed efficienty as well a warmer ride.

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shape

Postby jay » Sun Jun 13, 2004 8:48 am

consider an upside down canoe shape? like a Bowlus...how strong are your legs and how many gears does your bike have??
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Bowlus shape

Postby Mike Viger » Sun Jun 13, 2004 9:17 am

Jay,
I checked out the Bowlus. Looks interesting. My bike is 21 speed. As mentioned before I can easily tow 100+ lbs with the trailer I bought. With light weight materials I believe that I can keep the weight down. The area that I travel in is in the Otawa Valley. Very flat roads. Few hills, but they are gently sloped.

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Postby mikeschn » Mon Jun 14, 2004 7:54 am

Hey Mike,

Now you've got me interested in a recumbent... :?

I have a new 21 speed, so my old 10 speed could be chopped up...

I've also got the book, "Bicycle Builder's Bonanza" as shown here... http://www.atomiczombie.com/

So where is a good recumbent forum?

Mike...

P.S. Are we getting too off topic? Should I move this thread somewhere?
The quality is remembered long after the price is forgotten, so build your teardrop with the best materials...
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Postby Chip » Mon Jun 14, 2004 8:30 am

I am not a cycle'r but what about grafting the front of a bike to a lightweight rear frame with two wheels,,,sort of a 21 speed tri-cycle, your feet could tuck in just behind peddles and head to the rear,,waaa-laaa ,,,Tri-cycle,,Ric-shaw,,Tiny-trailer,,,

just killing time and brain cells,,,ya'll think bout it,,,

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Postby DANL » Mon Jun 14, 2004 4:02 pm

Here's a thought. Check out this folding cot/tent. You could just add wheels and a tongue. Maybe put a tear shaped cover over the folded package. The frame is probably steel rather than aluminum and that might be heavy. Could be aluminum though...

http://www.popuptimes.com/miva/merchant ... _Code=Camp

Another recumbent rider here -- EZ-1 Lite. I plan to carry both of our recumbents in the cargo-camper I'm working on.
The tiny trailer in the avatar is designed to carry our recumbents and sometimes sleep in. We LOVE having a kitchen in the woods and a place for most of our gear.
Dan Jones http://sunsetlanding.com/teardrop/teardrop_intro.html
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Bicycle Teardrop

Postby Jim Lewis » Mon Jun 14, 2004 8:26 pm

[Mike,
I would think you might want to make your frame from aluminum tubing (kinda expensive, but small amount needed). On that size of bed, just add a couple of cross members (which are needed anyhow), all you need to hold the mattress, is a piece of paneling (just like what might be on someone's living room wall). I like to use an air mattress, for foldability, and weight, and is very comfortable. On an area that small, you don't need even 1/2" plywood (way too heavy). I made a double bed in my enclosed motorcycle hauling trailer, by placing six small plastic buckets, up-side-down, on the floor (for height), then laid on a 4x8 piece of paneling, and used a double sized air mattress, and it sleeps much better than my Scamp ever did. My wife and I both sleep on it with no problems. You could build a light weight box, the size of a twin bed matt, and you could even leave it pumped up, and just let down the tent part, and RIDE. When folded, it would be only 6-8" high (much less likely to be affected by the wind (from front or rear). Of coarse, you could make it deeper if you want to, for more storage, or hauling pillows or whatever. I believe the air matt. would be lighter, and a lot more comfortable than foam rubber. Maybe you could use your bicycle tire pump to inflate the bed. Just a thought, gotta keep that weight down...LOL.

Jim Lewis
N. Carolina [/quote]
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Postby jimqpublic » Fri Jun 18, 2004 1:01 pm

Just stumbled across this site, and here are other (great minds or fools, you chose) discussing a bike trailer for camping/sleeping. I first considered this topic when I was about 8 years old. Then later when I met a guy touring the USA with a total of 200 pounds of bike, trailer and luggage. I asked why so much stuff and he simply said it was a yearlong journey so why not bring a bunch of stuff. He figured that he put the same effort going 60 miles with the full load as an unladen rider would do for 100, but he had an 8'x10' tent, ice chest, and cot.

So on to the design details.

No solid floor. Just look at most old style camping cots. They're a "trampoline" of a single piece of fabric held by an exterior framework. Do the same with coated nylon cordura and you're set. You would need to be able to have enough tension but otherwise it's light and weatherproof. Maybe just buy a cot to get started, then waterproof it with a layer of light coated ripstop underneath.

For walls and a roof I also have a suggestion- I've seen several applications of basically "plastic cardboard". Built just like the corrugated cardboard that boxes are made of, but plastic instead of paper. Stiff yet flexible in one direction, translucent for light, and provides decent insulation- probably about R-2. Aluminum tubing would be needed for a framework and then rivet and glue the panels on.

If the whole goal is just a quick-setting, bugproof and rainproof place to sleep off the ground, how about the Kamp-Rite Tent Cot from http://www.pahaque.com ? I have two of their products (TePee and Screen Room) and their designs and quality are the best I've seen in the tent industry.

Slap the Kamp-Rite down on top of a Burley cargo trailer and you're set. (Folded I mean)
Jim
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Kamp-Rite

Postby Mike Viger » Fri Jun 18, 2004 4:16 pm

Looks like an ideal solution. It weights 18 lbs., which is not alot. As mentioned before I bought a Bell double kids trailer. It is rated to hold 100lbs. I have carried that much hauling stuff and have not had any problem at all. The outside wheel measurement is 32". It should be possible to extend the existing aluminum frame to carry the Kamp-Rite. Something like a cartop carrier. Just place the cot on the ground for camping. This would allow a fair amount of room in the trailer itself for gear. The trailer is waterproof. This would also make the trailer and cot quite short, only about 36" long plus the tongue. A couple of cots could be easily placed on top. I guess I'll have to go out and make a friend now!

Thanks for all the suggestions.
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Kamp_rite follow-up

Postby Mike Viger » Fri Jun 18, 2004 4:18 pm

Does anyone know a Canadian supplier? If the cot is made in the US there will not be any import duty.
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