Instructables
Picture of build a 2-wheel cargo bike
as promised in my last instructable, here's my attempt to build a 2-wheeler. why? i got infected by the bike-building virus. especially cargo bikes are just awesome vehicles: you meet lots of new people ("hey, what's this?"), you can transport nearly everything you need on a regular basis and it's better than a car if you live in a city like me (no parking fees, no searching for space to park a car, no insurances, taxes, gasoline, healthier & better for the environment,...). so go on and build your own, it's not that hard ;-)
 
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Step 1: Donor frames

(sorry no pic) i got myself two donor frames from the local dump: an old 26'' mountainbike (hardtail) and a 20'' kids bike. the kids bike is just needed for the front fork and wheel, so if you find one where everything else is rusty and broken - take it! the other bike is used as a whole.

Step 2: Bulding the frame pt.I

Picture of bulding the frame pt.I
after disassembling the bikes completely i took the bigger one and welded two tubes (construction steel, 34x2mm) to it as shown in the picture.

Step 3: Frame construction

now it's time to decide how long your bike should be. after that i suggest to draw the front construction 1:1 on some paper and put the rear part beneath it. it helps a lot to see if everything fits together. after that use it to weld the pieces together.
some technical notes:
- be careful to have the main tube to the front parallel to the ground. this means to measure exactly as possible the dimensions of the front wheel and fork and the center of the back wheel (see drawing)
- for the steering angle of the front wheel i used 75°

Step 4: Steering

take the fork from the bigger donor bike and cut it in three pieces as shown above. then weld the top two pieces to another steel tube (something that fits inside the head tube (by the way, a good source to learn bikeframe vocabulary is here: http://aarline.info/hotaar/wp-content/uploads/2011/09/BicycleTypogram_mini_Black2.png )) and extend the bottom with a piece of steel.
mawwwk3 months ago

What was the angle of the tube that meets the fork steer tube?

carkat (author)  mawwwk3 months ago

hi, that angle depends on a few factors. i don't know the angle anymore, sorry. but i would recommend to draw the front in 1:1 scale to get that angle. the fork angle should be somewhere between 73 and 75 degrees (the more degrees the more stiff is the steering). then add the tube going down so that it doesn't interfere with the wheel (or the fender if you have one).

hope thathelps!

mawwwk carkat3 months ago

Yeah, I figured it depends on the rake of the fork. My plans of 73 degree angle, but I haven't been able to find any specs on cargo bikes to verify that this is anywhere close.

rwoudenberg8 months ago

If you can get a donor cheap mountain bike with a dual crown fork the tubes slide into the steerer! So by cutting the steerer you can braze the stanchion tube form the shock and braze the rest of the steere to the top. The rest of the bikes tubes can finish the external parts.Ill post a photo soon. Do you have your plans for the box?

carkat (author)  rwoudenberg8 months ago

sounds good, though i'm not sure i got everything what you wrote :-) a photo would be great! re. the box: unfortunately not. it was a build on the go - i took material i had lying around and built without planning. sorry!

Hahob 1 year ago
Beautiful! Im considering trying this build, I will post it here if I do:-)
carkat (author)  Hahob 1 year ago
yeah, please do so! thanks!
fvega31 year ago
this is very good i would like to build a few and pass them around.
carkat (author)  fvega31 year ago
thanks! passing them on would be a great idea - so people could actually experience on their own how it is to live a less car-centric life without having to make an investment beforehand :-)
Neander1 year ago
That is cool! I plan on making one like this but from a 3-wheel bike, so I have front and rear cargo space!
carkat (author)  Neander1 year ago
sounds great! if you're done with it a pic of your work would be highly appreciated. thanks!
Neander carkat1 year ago
Definately!
bpurcell22 years ago
Brakes--The weakest point of the two bakfiets I've built are the brakes. I'm one use a cantilever on the rear and a BMX side-pull for the front. The other uses old MAFAC racers front and rear--I've found that with a full load and going down a hill brakes are weak. On the next build I hope to use discs, especially on the the front.

Rap
carkat (author)  bpurcell22 years ago
yes, i can confirm that. though my cantilevers at the back are good enough, but the ones in the front are definitely too weak. the best solution would be disk brakes i guess.
Hey, so I'm pretty far along with my bike, coming along pretty well, and I'm going to attempt to go with disc brakes!! My biggest question for anyone out there is: how did you all engineer the kickstand to stay up when not in use? I'm assuming that professionally built bikes have some kind of spring mechanism, but not sure how I could build this?
carkat (author)  nthomas121 year ago

Thank you very much, that's exactly what I was needing!!
bainslie2 years ago
Fantastic build dude. I knocked one up myself recently with the help of a marine engineer mate who himself had made one first. Here's some stuff we learned.

Rod end bearings for both ends of the steering rod offer superior resistance in hard knocks [running into curbs/walls under load, etc]

a variation on the bucket style cargo area is the "deck" or "tray" style area with sides that fold down to make a totally flat tray for awkward loads [like old bike frames that have been chucked out ^_^] which can be more versatile. We were initially worried that without sides loads would slide out in corners, but the strange property [and vastly superior nature] of two wheeled cargo bikes is that they'll lean in the corners and most loads, if not really light, will stay right where they are. Of course if you have young children then that all goes out the window.

We also found that using a ladies mountain bike frame meant that in the [no doubt extremely unlikely] event of falling over sideways, the top tube of the frame doesn't tend to take you with it.

On the notion of moving the steering mount point higher on the front fork, it *does* allows your hard lock left to be a lot further left but we needed to do SO much readjusting and fine tuning to make sure that it would clear all the various bits that are so close together in there [we ended up cutting a groove roughly the circumference of a tennis ball into the front of the cargo deck] having said that, I've never ridden a bike without the clearance, and I would imagine it's pretty constricting.

Anyway, as I said, awesome build, it looks really schmick and it's always great to see another nutter on the cargo bike convoy.

Well done.
I'd love a pic of what you did for the steering problems you mentioned!! I just started building one of my own!!!
carkat (author)  nthomas121 year ago
a maybe better solution would be a cable/chain steering as done here: http://flic.kr/p/a6ackh
btw.: have a look at the other pics there. this guy is a genius. i only discovered his work recently.
Thank you for helping me kill a good bit of a morning when I went to his flickr site. You are right - some very clever solutions he has come up with and some interesting designs. I found most enlightening that he uses "girl's bike" frames when possible because of the lack of obstruction bar for getting on and off.
Sure thing! It's actually just a frame at the moment as I'm going to get it powder coated to try and give it a good shot at rust protection, so when its all back together I'll snap a few.
carkat (author)  bainslie2 years ago
hey, thanks a lot for sharing your experiences!
guruji12 years ago
Very good idea. Regards for this project. I think would be better if one can attach same type of carrier to a normal bike. So that it can be removed when not in need. The worst part to make the two front wheels syncronisation.
Anyway thanks to share.
carkat (author)  guruji12 years ago
thanks! sync'ing the front wheels should be quite easy (it just would need two steering-rods) but mounting the front part in a way that it works even for heavier loads will be hard to do, i guess. though... why not try? would be a good idea for a nice project :-)
http://www.myzigo.com
So this is the bike I saw that converts from Bike to Cargo bike, to stroller. It's not really much of a cargo bike, just a child carrier. Of course sometimes when you have something so convertible, none of the individual functions work as well. I have no idea with this product. It does look like you can't cary very much weight with it.
carkat (author)  nthomas121 year ago
thanks for the link!
I've seen this, it's very High Tech because of how the cargo box attaches to the bikes fork. I think it was a 3 wheeled version. I think they cost upwards of $5000.00 and probably would be difficult to engineer to build yourself. :)
carkat (author)  nthomas121 year ago
wow, that sounds interesting. any chance you could dig out a link to that? or some other hint? thanks!
really nice!! im planning on building one next month, already gathered everything except for the steel.
I was wondering how you've put the outer cups from the headset in the long headtube? (or did you find a tube with the exact diameter?)
I was thinking to get a tube with a bigger diameter than the original headtube, cutting the headtube in half and weld it to the tube with the bigger diameter...
or is there an easier solution??

:-)
I had the same question, but my headtube wasn't long enough to cut in half, so I luckily had a 3rd frame, cut it's headtube off and will weld it to the bottom of the steerer tube.

BTW don't know if anyone has advice, but I'm brazing everything because I don't have a working TIG welder at my disposal. Seems to work ok, what do you think?
carkat (author)  nthomas121 year ago
i don't use a tig either. there should be no problems with brazing.
carkat (author)  theboatdriver2 years ago
yep, i had a tube with the exact diameter for the headset (34 mm. steel was 36x2 mm), but i think your idea will definitely work. though i guess if you spend some time to find the right diameter for a bigger tube to enclose the headtube you maybe could find a tube with the measurements of the headtube, too.
good luck with your project!
nthomas121 year ago
Thanks for this project, I've started work on it myself. A couple logistical questions though... For the headtube extension, did you have tubing that had the correct ID for the lower bearing race to fit? I'm taking a 3rd donor bike's headtube and welding it to the bottom because my extension tube has the wrong inner diameter.

2nd, how long is your box? I'm just trying to get a good sense, I can figure out a good length, just wondering what you used so I have something to go on? Thanks again, I'm really excited to get this thing going.
carkat (author)  nthomas121 year ago
yes, i had a tubing with the correct inner diameter for the headtube extension. luckily.

box length at the bottom is 80 cm. though in the meantime i've come to the conclusion i should have meade it shorter. all in all the bike has a very long wheelbase which makes turning not easy sometimes. i would recommend to build it just as long as you really need it. if in doubt build a cardboard model in scale 1:1. holding it to the bike gives you a good guess.
bpurcell22 years ago
Nice Build BTW--you've given me some ideas.

Rap
carkat (author)  bpurcell22 years ago
thanks!
Nice.
Where do you store it?
This is mine:-
http://www.instructables.com/id/Long-John-Cargo-Bike/
and I have had to build a small lean to to keep it in...
Interesting that we both went with Orange...
carkat (author)  gsport george2 years ago
thanks. of course i know your instructable ;-) was a great inspiration, though well above my capabilities (welding aluminium!). both of my cargobikes and my road bike are stored in the inner courtyard of the house we live in. in winter it gets a simple plastic foil as garage.
greybear2k53 years ago
Saw a lot like this in Amsterdam, not sure if they were homebrew or if someone actually sells cargo bikes there.
carkat (author)  greybear2k53 years ago
colinus3 years ago
Wow, nice!
Figure I've made exactly the same thing two years ago. But someone has stolen the bike! Too sad.
Did you experience stiffness problems? Mine was like a chewing-gum frame, and really heavy (25 kilograms).
I'd be happy to see a video of the bike in use!
Great work.
carkat (author)  colinus3 years ago
stiffness is fine. the only thing one has get used to is the long wheelbase (more than two meters). and, yes, it is heavy. but it's a lorry not a porsche, so i'm fine with it. i'm just a bit slow when it gets hilly but that's ok. a video will be made next time i don't forget the camera, promised!
carlitos3 years ago
Nice idea. You can add seatbelts for transporting humans.
The mechanism for steering the front wheel reminds me
of Olli Erkkila's forkless cruiser bike.
http://www.ollierkkila.com/Site/?page_id=4&album=11&gallery=70
http://www.youtube.com/watch?v=7qiR7E3dpjk
carkat (author)  carlitos3 years ago
thanks! the cruiser bike looks quite funny. i wonder how it rides - if it's bouncy or hard to steer...
carkat (author)  carkat3 years ago
by the way: seatbelts were already mounted, but my kids didn't like to ride in it. they said it's going too fast... probably they're just used to sit in my other cargo bike which is a bit heavier to pedal and is not tilting in curves.
zazenergy3 years ago
Wow, such a great job!
carkat (author)  zazenergy3 years ago
thanks a lot!
RayKenn3 years ago
Excellent project ! Thanks for sharing the details.
carkat (author)  RayKenn3 years ago
:-)
thx!
rimar20003 years ago
Good work, but I have the feeling that the cargo compartment is a bit weak.
carkat (author)  rimar20003 years ago
thanks a lot! recently i was sitting in the box (75 kg) and all went well, so i think the load capacity is enough for my purposes (small kids, groceries, bag with laptop). of course one could bild it stronger, but then it would be heavier, too.