how to build a cargo bike

Step 15 Final assembly

box to transport kids and things with the bike. that's it :-)
further improvements will be some cat eyes and other security stuff.

Comments

[bigbunyip]

wicked bike dude, i've sen them being used on tv, in asian countrys, now i've seen how u made ur's i'm gonna have a go at makin 1, thanks 4 all the exelent details and pics. some good info in the forum 2, gonna try that caster angle bit, thanks

[sweavo]

great job! very inspiring. How is the steering now? I imagine if you power the pedals too hard when it's empty it tries to jacknife? If you build another vehicle, check out "castor angle" when it comes to bikes. I'm not sure how that translates to a beast like this though. I assume the box, when laden, is so heavy that it becomes the main consideration when riding and keeps it all stable. Wish I'd taken more detailed photos of the ice-cream bikes I have seen on my vacations now!

[carkat]

powering the pedals too hard isn't really a problem, it's the speed that makes the jackknife behaviour. yeah, the castor angle... i had a look at this before building but didn't know how to apply it to this trike, too... so i just kept it straight (means 90 degree) after my unsuccessful angle experiments.

[sillywilly]

carkat,
What about adding a couple trunk cartridges. You know, the ones that have a little gas shock in them? It might make it a little harder to turn but should stabilize the thing at higher speeds like little shock absorbers.
Silly Willy

[sweavo]

Yes. I see the problem. Forgive me if I repeat stuff you already know, but I want to be clear so that my point is not lost due to different terminology, etc. In bikes, you draw a line through the center of the headstock to the ground. The angle between this line and the vertical is the caster angle. The key point about this is that this line through the headstock hits the ground IN FRONT of the point where the tire touches the ground. That's what causes the wheel to pull itself straight when the body of the bike is travelling forwards. So "angle" is really a bad name for it. On your cargo bike, as you've discovered, the caster angle must be zero or it tries to lift one wheel off the ground to turn. So given a caster angle of zero, it follows that you must put the pivot ahead of the wheels in order to get the "pulling straight" effect. I think it would only need to be about an inch or two in front. Why do bikes not do this? I guess it's economics and ergonomics --- you'd need quite a lot of extra metal to bring the headstock up and in front of the front wheel. So that's my theory! If the details of your construction make it easy to do so, you could try shuffling the wheels backwards a little or moving the pivot forward a little on your cargo frame. Or both. No guarantees, but would be interesting :-)

[kb18951452]

I see what you saying about trying to lift a wheel up while turning. Looking at it from another perspective,couldn't that tilt in the headstock actually result in the rear of the bike leaning? If you turn right, for instance, don't you want to lean a little to the right(and into the turn)? If the headstock is tilted, then when turning, the front will stay level (cause of the two wheels) but the rear will lean into the turn (or out of the turn, depending on the angle of the tilt) Maybe the angle you used before was a little too much? Also, I am acquiring parts for this build as well, and my hope is to put the wheels behind the pivot (So it will tend to turn back strait, as opposed to tending to jackknife. I think i might keep the head tilted. Other than causing the rear of the bike to lean into the turn, can anyone see, or know of another reason why it is there?

[sillywilly]

I would think having the head stock in a straight up/down position would be best for a front cargo bike like this. That way no leaning over. If you leave the top tilted back like in a bicycle, the bike portion will lean to the outside of the turn. Turn it upside down then the bike portion leans to the inside which is better but not necessary. Dampening the turn with small hydraulic struts like the gas shocks that hold up a trunk lid or perhaps a pair of screen door closers without the springs might be better. It will make the turn a little harder but stabilize at higher speeds.
SW

[sweavo]

Unfortunately no, it wouldn't make the back portion lean. As the back portion rotates relative to the front portion, the angle of the headstock rotates with the back portion, so it always tilts straight away from the rider, trying to lift either the back wheel or the ouside front wheel off the ground. Mock it up in LEGO or something if you can't visualise this. It'll be a lot quicker than building the trike first then having to pull it all apart again!

[sweavo]

oops I mean "always tilts straight TOWARDS the rider" but all the rest of it applies.

[kb18951452]

I dont have legos, but i did have my Sons bike. Its constructed with the OPPOSITE angle, well, when its upside down atleast. So i turned it over, and used the handlebars like 2 wheels, to see how it would lean when the 2 "wheels" were being turned. When its got the opposite angle from your original construction, you get the rear leaning to the outside of the turn, lending that, if it were as you had originally constructed, it would cause the rear to lean INTO the turn. However, after doing this, it would seem that if you made the cart/basket where when it turned, it would be trying to lean forward a bit, and at the same time, the rear would be moving "Closer" to the back/bottom of the basket. This means that your probably need to raise the back of the basket, to prevent it from rubbing the rear/front connecting bar. I think i have noticed the baskets in these European bikes to be slightly raised in the rear to accommodate this.

[carkat]

right, makes sense. now i wish i would have kept that tilt. maybe the angle even wasn't too big since i tested it without load (even without the box). steering is always a problem if there's no weight in the front - leaning just a little to one side then causes one wheel to be lifted. the box is heavy enough to correct this but a bike leaning to the side when turning should definitely result in a better steering behaviour.

[sweavo]

It really doesn't make sense! Try it in lego or meccano or using cardboard and cocktail sticks.

[carkat]

ok, got it, thanks! maybe i'll try to improve everything next winter, when it's too cold for using the bike.

[burpinator]

great job looks sweet !! i have to make one look like fun

[carkat]

hey, thanks! in the meantime i started to make some improvements. will update this instructable when they're finished...

[burpinator]

looking foward to seeing it

[cararta]

Is there a track attached to the bottom of the box to fit the projection coming up from the frame? If so this would seem to stabalize the steering, maybe? Would have to half circle? maybe include a roller on top of projection in case weight in box tries to constrict movement?

[carkat]

no track. and i think it wouldn't stabilize it since it's not a problem of the load... steering is even more smooth when there's heavy load in the box. in the meantime i really think it might be the position of the wheels.

[onlylooklikepackrat]

I think the cargo box looks pretty classy. It is, in fact, why I opened your instructable, to find out the material and construction. So..tell me about the box. Thanks.

[carkat]

um, hard to say what the material might be in english. in german it's called something like "screenprint board". basically it's some kind of more expensive plywood - it's the same as the stuff used for building flight cases for musicians. thickness is 12 mm (0.47 inch), the parts are simply screwed together (holes are drilled in the upper part of the two boards to be connected, screwheads are sunk in [is that english? hope you get what i mean...]). if you want to get deeper into constructing such boxes you should talk to someone who produces flightcases. they have some really nice solutions (aluminium edges) to connect the boards, though they are a bit more expensive. or maybe someone is out there who wants to write an instructable on how to build flightcases?

[onlylooklikepackrat]

Thank you for the explanation. By the way, your English is excellent. Sometimes 'counter' precedes the word sunk as in "countersink" or "countersunk" but it is no more correct than yours. Nice workmanship on the box as well as the bike.

[Pothuset]

Well, it looks good, but I am the lazy type, so I think buying a Christiania bike is the right solution for me.

[Junkyard Dawg]

I think I may do something like this. However, I may look to another source for insperation: On a cruise a few years ago, they had "Taxis" on the dock, that were 3-wheeled bicycles in the traditional Tri-cycle configuration.I'm definately going to use what you learned in my designing and planing. Thank you for posting this instructable

[Quoniam]

Looks great. I go to try to make one like this in my vacation

[carkat]

let us know how it worked out :-)