No gas pump for this car! A Three Wheel Bike Car, with panniers, a cargo platform, 16 speeds, and a canopy. This project allows for worthwhile grocery trips, pleasurable joy rides, drive-through coffee or bank drive-ups, and the ability to carry what you need, whether that be croquet mallets, warm clothing, a load of groceries, you name it.
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This was an idea bubbling at the back of this bike mechanic's head for several years.To be honest, a recumbent or sit-down design never had appeal for me unless the extra bulk of such a machine could earn its keep by carrying loads. The three wheel design differs from a "long bike" with two wheels, by proving to be awesome on snowy or muddy pavement; there's no fear of laying the bike down in inclement weather. Sketching, collecting cast-off parts, measuring bike path widths, assessing what needed carrying, these went into formulating a somewhat unique design. 30 years of professional wrenching experience made technical issues like drivetrain design and general bike part selection and set up easy. Welding was required; my skills are rudimentary as to prettiness of the welds. This partly owing to using a basic flux-cored electric welder. But destructive testing showed that the joints have integrity. Mechanical ethics of good joint preparation and careful fabrication essential. Accuracy in measuring and cutting, and so on. The final step of painting the frame is waiting until I'm sure I don't have any more last minute add-ons to weld. I've been riding the machine since January.
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It would be nice to think you could forego welding to build this bike car. However the main concern would be having enough strength at critical points if using PVC.
1. This frame is long by trike standards. In carbon steel, it has a degree of flex as built. This is desireable for comfort reasons. The length allows for more cargo capacity as well. If you just copied the frame in PVC it would certainly flex too much. In steel, the degree of flex is within what I expect it can tolerate for many cycles of use. This allowed me to have a fairly spare and uncluttered frame.
2. The use of quality bike industry parts creates the need to accomodate their inherent design requirements:
-Robust dropouts or other fixtures to firmly secure wheels. (Bolt-on axles, or quick release axles, would crush plastic fittings.)
-Firm places to accurately bolt on disc brake calipers; they have very narrow tolerances and will certainly rub if not precisely mounted. (rubbing is an issue even as delivered on industry bicycles.)
The are other considerations, but I'm not saying they aren't solvable...
I would guess that a PVC frame would need to be designed differently from the ground up. Instead of a few long frame tubes, I picture a truss-type frame for rigidity. Think of a box beam made up of triangulated angles meeting each other to effectively resist bending forces. This will be bulky; room for the rider and for key components will need careful planning.
In one iteration I would consider large-diameter tubing for rigidity. Go big. It does create bulk and space considerations but careful design might overcome that. I'd use 4" in early drawings. If that wasn't going well on paper, such as when trying to accomodate tolerances for the bike components, then revert to many small tubes in a truss frame. (I think this second idea more likely to succeed but no guarantee.) This takes more careful layout, more joints to prepare and construct. The weight would be similar, you'd need more tubes and more joints if using small diameter. Try building up a 7' length in whatever design you conceive, then place it over two supports. Sit on the beam. Is it flexing too much? This is not a very rigorous test but will reveal the obvious "fails" in early experiments. If it bends so much your bottom drags the ground, you know it won't work. However less bending may still be too much for bike part tolerances.
A way to unite the PVC to metal dropouts for wheels would be needed, say by using 1/4" aluminum plate. The dissimilar materials of plastic-to-metal call for a large joint area, I wouldn't make the plates too small. It would be hard to keep joints from loosening unless a good overlap of plastic-to-aluminum was made. I'd think about slotted tubes epoxied to large tangs of metal extending well past the wheel attachment area. (Note that slots for axles cut into aluminum will be more vulnerable than same cut into steel.)
My front wheels are attached with one-sided wheelchair axles and sockets. This puts a lot of load on a single attachment point, but is met by the steel knuckles I made. I don't know how it would go using plastic. I picture the wheels flexing and angling inward at their tops if the left-to-right frame in front isn't made very stiff. And whatever plate is created to unite the PVC frame here to a front wheel would be tricky to keep bonded & rigid. It has to hold wheel for rolling action, and be robust enough for turning forces at the same time. Any flex would lead to rubbing and scraping between wheel and frame. PVC is not built to endure cycles of flex. It has the job of resisting internal pressures on pipe walls, and in house plumbing it must be supported at intervals. So it lacks many qualities that efficient frame-building demands.
I think long-term durability will be lacking using PVC. It may be in the "disposable" bike car category. But it could still be a fun project!
See my comment about my bike car being 100% human powered. (my reply to you was posted as a separate comment instead of as a reply.)
Just to clarify, my three-wheel bikecar is 100% human pedal-power. There is no motor.
(I did once think of eventually adding an electric motor after recent knee surgery, but have since found I can get by without it.)
lf you look at other photos in the instructible you can see the pedals, cranks, chain, and transaxle. The bulky rear wheel hub is an internal-shifting 8-speed device by Sturmey Archer, allowing me to change gear ratios and make my pedaling effort match the terrain or desired speed. But all motion is produced by muscle power.
The only external power on board is a small solar panel on the rear rack, that can recharge my 5v music device, or else charge AA batteries for my headlamps and taillight.
Check out this instructable, might be helpful...
Good luck!
thanks
Sorry I didn't answer right away. I don't have any experience with fabricating a-arms... But someone here at the site submitted a project that had a front end idea that I think they took from the front end of a quad..it had suspension that I think might be what you have in mind. I'll search here and reply again with name of that project. One thing I would say, if it will be self propelled, you will want to think hard about how to keep the assembly light weight. Even car manufacturer's list the weight of a-arm suspension as a factor. If you plan to scavenge parts from heavier motorized units remember that the weight was acceptable for that use, and that suspension was designed for motorized speeds and kinetic behavior.
You don't have to think too hard about that, except to try and spec frame member material that isn't overbuilt for weight of a self-propelled contraption. Thinner wall tubing, lighter spring assembly, things like that. The weight of a motor is a significant part of load you are trying to damp and control. Otherwise rider weight is main load if framework is appropriately lightweight. I don't know if you are going self propelled.
In bicycle industry, and even on some light weight cargo trailers, elastomer 'springs' have been used, no hydraulic shock, with coil-over springs if travel (length of up and down movement) is noticeable--sometimes no coil spring if travel is short. But a-arm weight I think wouldn't be worth having if only used for short travel..not enough suspension benefit to pay its way?
Sorry I didn't answer right away. I don't have any experience with fabricating a-arms... But someone here at the site submitted a project that had a front end idea that I think they took from the front end of a quad..it had suspension that I think might be what you have in mind. I'll search here and reply again with name of that project. One thing I would say, if it will be self propelled, you will want to think hard about how to keep the assembly light weight. Even car manufacturer's list the weight of a-arm suspension as a factor. If you plan to scavenge parts from heavier motorized units remember that the weight was acceptable for that use, and that suspension was designed for motorized speeds and kinetic behavior.
You don't have to think too hard about that, except to try and spec frame member material that isn't overbuilt for weight of a self-propelled contraption. Thinner wall tubing, lighter spring assembly, things like that. The weight of a motor is a significant part of load you are trying to damp and control. Otherwise rider weight is main load if framework is appropriately lightweight. I don't know if you are going self propelled.
In bicycle industry, and even on some light weight cargo trailers, elastomer 'springs' have been used, no hydraulic shock, with coil-over springs if travel (length of up and down movement) is noticeable--sometimes no coil spring if travel is short. But a-arm weight I think wouldn't be worth having if only used for short travel..not enough suspension benefit to pay its way?
That aside, FANTASTIC Job!!
How much is the overall weight of your Bike Car? :)
However, definitely stay away from trying to directly bolt one side of an ordinary front wheel's axle nut onto any kind of steering knuckle. That set up is not right for a cantilevered attachment. What I discussed was modifying a front hub by removing it's factory axle, pressing in cartridge bearings with a large enough I.D. to insert a continuous long through bolt, with a bolt head on the outboard side of hub, and the threaded end going to steering knuckle. With a lockwasher and a Nylock nut to secure it.
Good question, the wheel attachment is something many folks wonder about. Lacking special wheelchair or cart hubs, many builders try to fashion a fork type arrangement so they can use ordinary front wheel hubs. I don't like the way that forces you to use a caliper brake, is flexy, and it also makes for slower flat fixes. (with open-wheel attachment such as on a wheelchair, you don't even have to remove the wheel in order to change a flat because no fork blade is in the way of pulling the tire off to the outside.)
The system I used was from a set of quick release wheelchair hubs. I actually modified a pair of front disc brake mountain bike hubs, by converting them to accept sealed bearing cartridges and the solid, side-attach wheelchair axles. I got lucky and the aluminum disc hub's machined recess that came with steel press-in cup races for ball bearings, happened to be the same press-fit dimension to accept the catridge bearings. This lets the heavy steel rods from the wheelchair hubs fit into the disc brake hubs, giving me a clean and powerful set up. I laced the hubs to mountain bike rims.
So the support for the hub is all on one side, with a release coupler that bolts onto the steering knuckle I fabricated. This coupler has a chrome release sleeve that can be moved to release the solid axle for wheel removal. It works similarly to a fitting on a compressed air hose for a nail gun or such, you push the outer knurled sleeve aside and a captured, spring loaded ring of ball bearings retracts, releasing the axle from the sleeve.
However, there are cart hubs that bolt on from one side, instead of being this fancy quick release method. That would be less expensive. I've had the wheelchair hub parts for 20 yrs or so and so can't give you current prices, but retail would have been over $100. If I hadn't had QR axles on hand I would have pressed in some cartridge bearings to a pair of front mtn bike disc brake hubs and then fitted a high strength bolt through the I.D. of the bearings. The largest I.D. possible, to allow a large diameter bolt. Getting bicycle industry hubs ideal so you can use bicycle brake parts. A pure hardware store cart hub or wheel could work but you wouldn't be able to mount disc brakes to that.
When I get a chance, I'll make a sketch of the hubs, axle, and steering knuckle design.
As for the weight of the bike car, too unwieldy to weigh on a bathroom scale, but I'm guessing around 65 to 70lbs total weight.
As a regular mtb-er I do know that there are axles with 20mm diameters for mountainbikes, there also are 14mm ones. I may look into those a little more to find out if I can modify them, or simply use a wheelchair axle IF they are the same diameter... I can already see, this Project is not something to start without proper research, and preparation.
Thank you for your thorough answer!!
I really want one, and if you add an engine on the back, you have an easy dune buggy!
keep up the good work, and good luck for the competition!
It would certainly be possible to put a motor of some kind on this bike car.
I think I would favor a battery type, and probably would run it to drive the jackshaft with an accessory sprocket. I would try to locate related hardware away from the back wheel, maybe set up the battery at least under cargo platform that is made of expanded metal mesh. But as it is, I am enjoying the freedom of just pedal power. Electric motors, and especially batteries definitely add weight.
Now here is what I had set up on my bicycle a while ago and it may work for you. The problem was on my bicycle I couldn't really add a whole lot of weight so the battery was only 36 volt (2 miles range at max speed :( .)
try hub motors they work well:
http://www.electricrider.com/crystalyte/
You're right, the weight esp. of battery is considerable, and unless handicapped in some way, to my mind not worth it. Pedaling isn't that hard with this gear range. Might only gain speed--but for only a short range as you said. And then rider is stuck pedaling the weight of motor/battery home without assistance if battery dies. I am a fan already of hub motors. Good weight distribution, decent torque, etc. My desire to emphasize human power, and my specific desire to be able to use the lovely 8- speed internal hub in the rear drove my design in the direction I took. And I'm pretty happy with it.
If I was compelled to build same project with a motor, I would select a hub motor, with a freewheel on it or else a freewheel on the jackshaft. This would accommodate multiple speeds well enough. But I can't overstate the elegance and high function of the wide gear range Sturmey Archer internal 8 speed hub. Over 300% ratio. Better than most plain freewheel/chainwheel stock arrangements.
Aren't the many possibilities fun, anyway. Thanks for your comments.
I prefer gas powered bicycles because you can add a very hard to pedal gear, so that when you reach 35mph with the gas engine you can still get exercise from peddaling.
Thats what I would do :)
Thanks for asking, I'll get a photo or two in close-up posted here for you, maybe a sketch of the tensioner assembly, too.
Keep in mind this isn't the only way I could have done this. There's such a thing as a two-pulley wheel tensioner= more chain wrap-up, instead of the single one made by Simple that I used; there's also a tensioner that fits under the right side, fixed cup of the crank bearings. This has an arm and a urethane wheel that puts tension on the chain very near the chainrings. (instead of back at the jackshaft sprocket.) I had several parts lying around already and went with what you see here.
FYI. when you examine the photo showing jackshaft before it's mounting washers were welded onto the frame, you'll see a freewheel instead of single cog mounted. In the end I decided that wasn't necessary, what with multiple chainwheels, plus the 8 internal speeds of the rear Sturmey Archer hub. A rear derailler talking to a freewheel, versus just a tensioner under a single sprocket, would mean one more shift lever in the cockpit, and more complexity. Not hard to do, but as I said, not really needed.
Couldn't you just add 6-8" to the frame rails where the seat is mounted, and make provisions for an adjustable seat? This seems to me to be a much simpler method of accomodating different sized riders than adding & removing chainlinks, etc.
For a faster top speed, you might consider a 2nd chain/gear set mounted 'reversed' to normal IE: The pedaled chain drives the small side of the set, then the larger side drives the final gear set (just something to mul over next winter).
I like your ideas, great I'ble! ;)
I'm slightly splitting hairs in the case of my bike car; it's not as if the handling becomes awful with these small changes, not at all. But as someone who has spent years riding, including more than a decade competitively, and who is interested in the handling subtleties, I've set this thing up with that in mind.
That said, there truly is the ability to just do the adjustments at the seat-end of things: but funnily enough, even that takes time, because you need to unclip the kayak seat, move it forward or aft, then slide the back pillar as well after loosening the clamp bolts. (not hard to do, but just saying, for comparison.)
The issue now becomes, are the steering bars still in a good position for the taller or shorter rider? They can live with it I'm sure, but it's true that the steering does not move with the seat, it is separate system of a bar and cables. (which would have to be lengthened or shortened if new rider was fussy.)
Meanwhile, for my purposes, there's nothing slow or hard about removing or adding links to the chain after quickly sliding the crank mast. Especially if "quick links" are used, such as made by SRAM or others. These have a keyhole fastening, for tool-less assembly/disassembly. This means you aren't having to drive out any chain pins which on most modern chains require the use of a special bullet-shaped leader to keep from gouging out the hardened side plates. These are consumable items, known as "hyperglide pins" in Shimano-speak. (some folks don't know you can't drive existing chain pins in and out willy-nilly anymore. The hardened side plates will shed fingernail-shaped crescents of metal, enlarging the holes and weakening the chain. The increased side-loading of modern shift patterns requires that chains be hardened, with robust pin design.)
About your high gear comment: I don't get a clear idea of your design, would love to see a diagram--even though my high gear needs will be easily served by changing chainwheel and/or rear sprockets.
Thanks again, stay tuned I'll be posting more pics of cable steer for someone who asked earlier.
This is a video of a snowy spring ride on the bike car. Winter just hung on here in the Rockies. This was before the canopy was installed. The camera couldn't take a wider view than from the pedals forward, but you'll get the idea. Paste this into your address bar, it'll go straight to the vid, includes some fun "ride" music.
http://video.ak.fbcdn.net/cfs-ak-snc6/79204/258/1753904280501_61622.mp4?oh=af718f3da5bec4e1c39efbed347b39d5&oe=4DCDA600&__gda__=1305323008_942dc4172f7ae06c83e13aae465cbcd4