Step 3: Sizing Things Up

So; have you got your trike all set up and ready to go?  GREAT.  You'll need to take a few key measurements so that the velo shell can be designed to fit around the trike (with YOU on it!) If you are 6'4" and already have a Catrike Expedition, you can skip this step.

Gather up a bunch of scrap cardboard and lay it on the ground under the trike.  It should extend past all the corners of the trike.  Tape or otherwise secure the trike to the cardboard, so it doesn't move while you are taking measurements.

Using a carpenter's square and a level, marked out the following dimensions of your trike.  I simply drew the "outline" on the cardboard, then measured them later with a tape measure. 
  • The very rear edge of the back wheel
  • The front edge of the rear wheel
  • The center of the rear wheel
  • The furthest forward that the pedals will extend
  • The center of the BB/pedals
  • The very outside edges of the front wheels
  • The front and rear of the front wheels
  • The maximum and minimum outside extension of the front wheels when fully turned
  • The width of the seat
  • The height of the seat
  • The lowest point on the trike (frame, chain, chain hanger, etc)
  • The maximum possible height of your knee when seated, with feet on pedals
  • The height of your shoulders when seated
  • The height of your eyes when seated
  • The top of your head when seated
  • The width of your shoulders
Draw a line between the two front wheel axes, and another intersecting line between the center of the BB and the center of the rear wheel.  The intersection point may be considered the "origin," and you can take all your measurements based on this point.

Based on these measurements, you can determine how wide the velomobile needs to be, where the cutouts for the wheels should go, how tall it needs to be, and how long.  If you don't want to design from scratch, you can easily resize, stretch or move various parts of the model I made to suit your trike.  For instance, if you are shorter than I am, you could lower the hood and pull in the nose a bit.  You may end up with a few extra folds here and there, however.

Hi all! <br> <br>I'm glad to see my design come to life in an entirely different corner of the planet and many years after publication (2004!). <br> <br> It was sort of orphaned when we started making the carbon/kevlar WAW velomobile professionally and I lost interest in covering my trike. The Bratmobile (a word play on my name and the looks of the shell) was a design exercise driven by a curiosity how efficient a faceted approach would be. As it turns out it confirms my presumption that, at real world traffic speeds, a low resolution approach of a decent form factor could yield 80% of the efficiency for 20% of the price. <br> <br>The subsequent versions narrowed the frontal area making the sides flush with the wheels, then eliminated the ridges in the transverse direction. A few alterations on the latter design were constructed. Funnily enough the builders came to the same conclusions and stepped up to a purpose built velomobile. Go and proselytize! <br> <br>The design, design principles and drawings are open source as long as credit and some much needed publicity is given to www.fietser.be. <br> <br>Regards, and thanks to the Instructables community and Jeff-o. <br>Brecht Vandeputte arch
Hi Brecht, welcome to Instructables!<br> <br> Thanks very much for filling in some backstory on your design. For all this time I felt the bratmobile was too cool to simply fade into the ether, so I am proud to finally give it the attention it deserves.<br> <br> To everyone reading this, do take a moment and check out the amazing work Fietser is doing with its legendary <a href="http://sites.google.com/site/mobilitylabbe/Home/waw" rel="nofollow">WAW velomobile.</a>&nbsp; Oh, how I'd love one of them parked in my driveway!
<p>Thanks so much for sharing your fastening tests. <br>Did you try bending the superglue? That one is pretty brittle. I've been thinking of testing out pure silicone from a caulking gun. I suspect that will require another mechanical fastener like zip ties to keep it together. Being water tight is a requirement of mine.<br>Thanks again!</p>
<p>Jeff, that's a really awesome shell you've created! I would love to create this shell for my Catrike 700. I'm not sure I could build something like this, but do you think you could give some pointers or help in any way to modify this plan for the Catrike 700?</p>
For a lighting idea I wonder how much cooler it would look with ELwire
This is a slick design! That being said, my wife has a (two wheel) recumbent, and I'll make the same observation here that I did to her: recumbent bikes put your head at exactly the right elevation to be struck by the bumper of a car. (And having been hit by a car while riding a bicycle, I can tell you this isn't a trivial consideration.) They may be more comfortable, or (in the case of a three-wheeler) easier to ride, but I prefer having my head up high where I can see more, and where it's less likely to get mushed in the event of an accident. <br> <br>You might also consider adding a flag on a stick (or some other attention-getter) that would add some height to your riding profile and make you more readily seen under certain circumstances, such as to a driver who is several cars back, or over the crest of a hill.
I agree with the need for a (fluorescent) flag-on-a-stick like these <a href="https://www.google.nl/search?hl=nl&client=firefox-a&hs=uvS&rls=org.mozilla:nl:official&q=fiets+veiligheidsvlag&bav=on.2,or.r_gc.r_pw.r_qf.,cf.osb&biw=1343&bih=841&um=1&ie=UTF-8&tbm=isch&source=og&sa=N&tab=wi&ei=Lf-4T9LfCuWm0QXVvaDRBw" rel="nofollow">https://www.google.nl/search?hl=nl&amp;client=firefox-a&amp;hs=uvS&amp;rls=org.mozilla:nl:official&amp;q=fiets+veiligheidsvlag&amp;bav=on.2,or.r_gc.r_pw.r_qf.,cf.osb&amp;biw=1343&amp;bih=841&amp;um=1&amp;ie=UTF-8&amp;tbm=isch&amp;source=og&amp;sa=N&amp;tab=wi&amp;ei=Lf-4T9LfCuWm0QXVvaDRBw</a><br> <br> You might even want to make your entire vehicle fluorescent!<br> <br> When there are enough bikers in your area, maybe it's time to start lobbying for bike lanes, like we have in the Netherlands.
<p>Bike lanes are the stupidest thing ever devised by man. It lulls cyclists into a false sense of security and complacency. </p><p>A bit of paint on the road is utterly meaningless. They do not repeal the laws of physics. The tiniest bit of moisture or loose materal on the roadway can and will cause vehicles to skid. When that happens they will happily slid over the paint and mash the oblivious cyclist secure in the knowledge that they're safe because they're safely in a bike lane.</p><p>A bicycle is a vehicle. If you can't ride it on the road with the same concentration you'd would in any other vehicle, then you have no business operating it at all. </p>
<p>I'm talking about real bike lanes (like we have in the Netherlands). Bitumen/asphalt with a different color, not just paint. Not a piece of road that's been stolen from the cars, but an actual, separate bike lane. If you're going to copy something, you better do it right when safety is an issue.</p>
<p>Is there any two wheel forward trike designs with an upright seat position? My back would never tolerate a seat angled back like that.</p>
<p>hi lokisgodhi. After being hit by a bus and having spinal surgery I now ride/drive a velomobile. The last thing I need to worry about is my back because of the semi reclined position. You must try it! Much better than a normal bike, you just lay back and relax and put your efforts into pedalling, steering and those around you. </p>
I realy love this one :) <br>Do you have a photo of what there is inside?
Sure! Just check out any of the pictures of my trike without the shell. That's pretty much all there is inside. ;)
Thanks for this very interesting instructable. Today I bought some Coroplast and glue to try out your method. Have I understood it right that you do NOT put glue onto the tabs, just in the seam? I tried it, and the area that is glued is so small that it was not strong at all. Did I misunderstand?
Me again, there's a CAD program called freecad. Its free and it works great once you get the hang of it. And i have been able to export a solid mesh (.obj) to Pepakura. I just had to isolate and remove the unwanted inside panel. <br> <br>Thanks again jeff.
Thanks, I have been looking for months for a program that converts 3d to 2d.
Oh man. Luke Skywalker's landspeeder. I've gotta do it now.
Love it! <br> <br>Sorry to be a worry-wart, but if you accidentally bumped into even a bush you would be thrust into your coroplast like a guillotine. I have a friend who went through multiple surgeries to his face and neck after being sliced by cardboard that hit him on edge with some mass behind it. <br> <br>It would be great if you could at least wrap some of that grey foam pipe insulation from Home Depot around the inside of the sharp edge of your cockpit maybe with something even stronger underneath it so that in a crash the coroplast collapses like a crumple zone of a car rather than just chops you in two. <br> <br>Again, sorry to be Debbie-Downer, but I've seen this injury in the flesh, so to speak. <br> <br>Awesome work. I will borrow some of your gluing research for a project of mine.
A valid concern! My mom worried about the same thing. And I know what a coroplast &quot;paper cut&quot; feels like - I received a few when I was doing the modifications in the last step. Nothing serious though. <br> <br>I'd suggest wrapping any of the exposed cut edges in vinyl tape, such as electricians tape or floor marking tape. That should blunt the sharp edge pretty well. You could also wrap thin foam around the edges to be extra cautious.
Your Mom and I are on the same page. But it isn't the paper-cut I am worried about, it is the blunt force trauma that does the real damage. In my friend's case it was a broken jaw and crushed windpipe, in addition to lots of blood.<br><br>The problem is that all the energy from your momentum will be concentrated on the thin 1/4 inch edge of coroplast. lt is the thinness that creates the danger, not the just the sharpness. It's the same issue when snowmobilers accidentally hit a barb-wire fence at speed. The barb doesn't kill them, it is the rounded wire slicing through that gets them. Or the same issue with the steering column on older cars that used to kill people by spearing them even in fairly minor accidents until they made them super padded and collapsible.<br><br>You did great gluing experiments. The same could be done for this risk factor. Duct tape a steak or chicken leg to concrete block and then drop it from a step ladder from 10 feet in the air onto a well supported piece of coroplast on edge and see if it doesn't just chop the meat in half.<br><br>So the vinyl tape is a good start, but then you've got to do something to widen out the edge so that the force is dissipated across a broader area, that is why the foam suggestion, but I worry the foam itself isn't very strong so maybe you need something quite strong like a split rubber hose to go from the 1/4 inch coroplast out to 3/4 of an inch or so and then the foam on top of that.<br><br>Sorry to have scary visions, but your mom and I want you to live to do more cool projects.
Hmmm, the next time I visit the hardware store I'll be sure to see what they have. I'll update the Instructable with more photos when I can.
How about fitting the seat with a five point harness (they aren't crazy expensive or all that heavy - check SummitRacing.com**)? Then you aren't running anything vital into the coroplast. <br> <br>** http://www.summitracing.com/parts/BOB-30298-19-238/
Actually your idea isn't a bad one but IMO the harness you linked is in fact &quot;crazy expensive&quot; at $141, and way overkill for the forces involved. I took your idea in a more reasonable direction and Googled for &quot;Go Kart Safety Equipment&quot;. For a little over $20 you can get a three point harness that will do everything the professional five point harness does.
All I can say is.... WOW! and Well Done. :-)
Well, I just found my summer project. now to get a recumbant bike and materials... <br> <br> <br>I also had an idea of just making a frame and covering it with a large sheet(s) of heat-shrink plastic. Would this be any cheaper or more expensive/ harder to do?
I'm not sure it would be an improvement. <br> <br>Chances are, the flexible plastic would act as a parachute, trapping air or making it roll turbulently across the surface of the shell. That's not what you want! <br> <br>As for the frame, what would you make it from? Depending on what you choose it could be difficult. But, a suitable frame could make a good foundation for a fiberglass shell... <br> <br>I'm fairly sure that coroplast is just about the least expensive material you can use to build a shell from, especially if you use discarded election signs and zip ties.
You need to change your username to Jeff O'Fabulous! Congrats!!!!
Thanks, bajablue!
You need to change your username to Jeff O'Fabulous! Congrats!!!!
You need to change your username to Jeff O'Fabulous! Congrats!!!!
Amazing! While I can't stand recumbents for any other purpose, this is pretty snazzy if I say so myself. And this Instructable was incredibly thorough, kudos to you for that too. <br>The ride looks incredibly fast, and in the video, my computer just started to play the william tell overture as you pulled out of the driveway, so it only added to the effect.
I sing a little bit of it myself, every time I leave the driveway.
Absolutely amazing!!
Do you have a picture of the whole thing lit up?
Soon; once the lights are finished! There will be a separate instructable documenting the lights.
I am very fond of this. I am also very fond of the pictures at various locations. They bear a strong resemblance to &quot;Garden Gnome Liberation&quot; photos I've seen.
Thanks, I appreciate it. It was fun taking those photos; people would come up and chat about the velo or just stand and ogle. I imagine I'll have to get used to that from now on...
I really want to make one, but I just need a base vehicle. Can anyone recommend a trike or recumbent that is much more affordable than the 2500$ one in the Ible'? <br>
Check out AtomicZombie.com for quite an array of beginner-oriented plans (including various recumbents and trikes). Even if you are not up to it, my guess is that you know of someone with sufficient welding and fabrication skills to do it for you.
Yeah, I think I might just buy one. I have seen lightweight recumbent trikes in the 500$ range, but I was just wondering if anyone can reccommend a good model for a cheaper trike, based on the durability. I just don't want to shell out the money for a cheaper trike (still a lot of money on my student budget), along with the cab materials, and then have it break.
It's unlikely that even a cheap trike will flat out break. The cheaper ones will just be heavier, and will be equipped with cheaper components. You can swap out the components for better ones as they wear out or as you can afford them.
I think I might do that... this looks pretty amazing! I was a bit confused about one part though- your head sticks up out of this thing, right? It isn't a fully enclosed cab. If I make one it will have a fully enclosed cab.
Yup, it's a head-out design. Windscreens tend to fog up, especially in the winter. That's why I decided not to include one. But it should be easy enough to add one if you want it!
Yeah, my design will probably be like yours in it's geometric aerodynamics, but open from the side and have an almost bubble like clear canopy. Obviously, this &quot;Bubble&quot; would be made with flat faces, not curved, as I have no tools to curve large pieces of plastic. <br> <br>Also, it would be cool to make a miniature mock-up of your design and run it though some wind tunnel tests. It looks quite aerodynamic from either end, but how does it do with gusts from the side, or buffeting winds from passing vehicles?
Look into the history of custom cars, particularly Ed Roth, as he used a lot of bubble tops. I don't think that making an &quot;almost bubble&quot; is by any means beyond the means of a motivated hobbyist. <br> <br>Just make sure to take lots of pictures - it would make a great Instructable!
I think I will just use sheets of acrylic framed together, nothing overly fancy.
You could probably form one piece of plexiglass over a glass salad bowl or something like that. In fact, I wouldn't be at all surprised if there's at least one 'ible on it. <br> <br>Or I could see wither inside or outside the bottom and sides of a glass baking dish, and then cutting the sides to a triangle shape - voila' windshield!
Well, maybe I could, but I am lazy. Also, I think the windshield would be a bit larger than a salad bowl. <br>
A punch bowl? :)

About This Instructable




Bio: By day, Jeff is the Jack of All Robots at Clearpath Robotics. By night, a mad scientist / hacker / artist / industrial designer wannabe!
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