home built Bakfiets

[artur elias]

Think about my idea of making a fork with long horizontal dropouts so you can easily experiment with trail changes

I gues that means kevbo and Facebook Kevin are the same person? ;-)

6. Be mindful of your handlebar height as compared to your front passenger's head. Some bike provide way more space than others for this.

That would be a definite advantage of Design 1 - handlebars farther back and away from the passengers heads.

What do you guys say?

60mm trail seems very high

I have no clear opinion on that. There is at least one bike, the Monark Lon John, that appears to have zero (or almost zero) trail due to the fork with very procunciated rake. Others have positive trail in varying degrees. I already have a good fork, so if less trail is desirable, I should go for a wider head tube angle. Or try your idea wich would be a nice way of getting to know the effect of different amounts of trail on the same bike, through direct experience.

[artur elias]

Artur, the CETMA is 8 1/2 feet or so, so they didn't do much to cut down on size (or weight) compared to regular bakfiets. I agree that once you are on the bike, length doesn't matter. It only is an issue for me when I try and lock it up at a regular bike rack.

Let me see, 8 1/2 feet is almost 2,6 m, right? I think that puts the CETMA in exactly the same league as Balfiets.nl, lenghtwise.

With Design 2 I get about that same figure (2,58 m). But, with Design 1, wich does no major alteration to the donnor frame, I get almost 20 cm "lost length/area" that are added to overall length wich turns to be over 2,7 m even with a slightly shorter cargo bay area. Design 2 carries more cargo despite been shorter.

I think all manufacturers opt to make the cockpit short (even more so than Design 2) so they get the biggest cargo space with shortest possible overall length. I guess that's also the reason for the tilted seat post you see on most box bikes - so the rider has enough space to pedal and steer.

I would say however that the longer your runs of steel tubing are, the more flex you'll have on your bike. I think flex is a bigger issue than weight or total length.

I think you're right. I intend to minder that flex with the braces that come from the box "frame" and bond it to the steering column and head tube.

I also think flex is not so bad when it happens far away from the drive train.

[MossHops]

If I recall correctly, most cargo bikes out there, use a design closer to #2 with a vertical steering tube. I assume this makes it easier to work with the steering linkage. It seems like the exception to this is Tom's who probably angles his steering tube to accommodate the "conversion" of an existing bike. If building from the ground up, I bet the vertical steerer tube would be the way to go.

[artur elias]

I've found this interesting comment on bikeportland.com regarding CETMA's steering geometry:

"steering geometry/feel with bikes in this format is a subject near my heart. trail isn't the only important factor. but i'm firmly of the opinion that very low trail, in the 20-30mm range, is more appropriate than higher values, and this bike has that" http://bikeportland.org/2009/01/26/a...n-eugene-13881

Then I finally found a picture of the CETMA Cargo (I think it is one of your, MossHops!) that suited itself for inferring angles and some dimensions. I'm really not good in math, so I did my calculations several times with 2 different reference values.

Trail would be nothing less than 50 mm, more likely 55.

Questions:

- is my math/guess/whatever wrong? (no surprise if it is)

- did Lane modify the trail after that first prototype?

[artur elias]

While I'm still at it:

I said before that head tube angle varies a lot among well known box bikes.

It does, but also I found out that MOST of them are in the upper range (give or take one degree less or more):



Monark Long John, the classic - 74-75º (and ZERO trail!)

Bakfiets.nl - 74º

Long Harry - 71º (that one is a not so well known, apparently very sturdy and well engineered cargo bike from Germany)

CETMA - 75º

Metrofiets - 72º

I've found just two bikes with less than 70º (both with 68º), the Gezelle and the Urban Arrow (which is "just" a prototype, although a very beautiful one).

[MossHops]

Yeah, my picks have a pretty good side profile, so figuring out trail should be sort of easy: https://picasaweb.google.com/1053853...t=embedwebsite

That said, the headset was a little loose when I took these pics, so trail could be a little off. I know CETMA made changes throughout their run (threadless vs. threaded headset, different fork diameters, different stem diameters, addition of eccentric bottom bracket) so it isn't out of the realm of possibility that they switched up rake as well.

[artur elias]

Those are very nice photos. Not only for analysing purposes!

I've found one bike with some rather strange feature - negative trail:

http://www.defietsfabriek.nl/nl/nl/147/model_am/19/995

I wonder how does that steer and feel?

[tedi k wardhana]

I would love to make a 16" cargobike (front loader) that can be separated like the cetma. so it can be easily transported in the taxi trunk.

anyone done it already?

[artur elias]

I've been very busy about the project. I've made a couple more drawings and made all major decisions regarding dimensions, geometry and material. Mild steel tubing through out it will be.

I've also finally made up my mind about building some sort of jig. I got a lot of inspiration from many home builders who post their acomplishments everywhere on the net, plus one very informative article on jigs for motorcycle frames. My jig has a little from all. Let's see if it can really do some good to the alignement of my coming Bakfiets.

I've been reading, learning and practising lots of stuff on metal working. Mostly from Atomic Zombie (tutorials, blog and forum). Incredibly rich source of highly usefull info. Frame chopping for parts recycling, tubing preparation (fish mouth cutting and the like). I even bought some plans for future projects.

http://www.atomiczombie.com/aztv/

Tube notching can get a lot easier with this (among ohters) online software for calculating and printing a paper template for cutting fish mouth in every conceivable diameter/angle/off set combination. Great stuff.

http://www.cycle-frames.com/bicycle-...e-Notcher.html

I'll up load pictures whenever I have time - for that.

[artur elias]

The Brazilian Bakfiets is a reality!

Frame has been completed and bike test ridden on saturday night - without brakes or derailers - just in time for a presentation on Utility Cycling at the I World Bike Forum which was an amazing event (the forum - presentation was not bad either).

http://forummundialdabici.com/home-en/

http://www.facebook.com/pages/Forum-...57698500962118


It rides very well. Steering works perfectly. It's a lot of fun.

Almost couldn't believe it at first. A couple months ago I knew so little about how to reach my goal. I felt like giving up a couple times when things got tuff. But I had already invested too much time and energy so I sort of had to find a way to go on each time. Welding technician Rubimar "Solda Tudo Toda Hora" has done so much more than just delivering his service as a welder. He embraced the project like it was his own. He allowed me to use his shop and all his tools while he was working for someone else. The picture was taken there.

IMG_2248.jpg

Right now I'm working on a flat aluminum platform for the cargo bay while I figure out how to build a nice box for the kids.

[artur elias]

There has been a lot of talk about steering geometry on this thread.

I'd like to share a picture - it shows the exact moment when I reached the planned 74º head angle and a nice tube match (working with angle grinder and file and checking with a template). A joyfull moment!

That angle has probably been changed a little bit while test riding these days - there is way too much vertical flex in the front frame which may have caused some twisting to the joints. One reinforcement is already in place and more are coming.

IMG_2068.jpg

[MossHops]

Great job. The bike looks like it will serve you well! I think you thought though the design issues clearly and will end up with a great kid hauler. Cheers!

[artur elias]

Great job. The bike looks like it will serve you well! I think you thought though the design issues clearly and will end up with a great kid hauler. Cheers!

Thanks MH! My Bici-Caixa is never going to be as nice as your CETMA, but I hope it'll do the job well.

Right now I'm a little concerned about vertical flex in the front frame (cargo bay). It doesn't feel right yet, even after adding one big V-shape conecting the cargo frame to steering tube and top tube (yes, everything together). I'm sure the bike still need some kind of "spine" under the main big tube, but I'm uncertain about the exact shape and dimensions. Right now I'm leaning towards the Metrofiets design. CETMA doesn't need that, because the frame has quite another conception (which I think looks perfect but was a little too complex for me to emulate).

Meanwhile I've added a flat platform and made a lot of testing:

- hauling up to 3 small kids over short distances
- riding about 40 km in one day including one mass protest ride with another 1000 cyclists (a lot of fun)
- getting groceries from my favourite organic shop (yes, that is a water melon! and that's one BIG curb which barely took half of the available space)

http://www.flickr.com/photos/2376346...2261/lightbox/

(can't get picture embedded for some myterious reason)

[artur elias]

The Bici-Caixa (=bakfiets in Portuguese) is getting better all the time. All reinforcements in place and tested. Vertical flex reduced to an acceptable level.

(I'd love to compare it flex-wise to professionally produced bikes, but that's not possible, unfortunately)

There were a couple mechanical bugs that have been solved. Both head sets working flawlessly now. Steering is very smooth. Good brakes and derailers.

I found an old rack that fitted perfectly. I'm planing to add a front axle so I can tow another (my son's) bike.

I believe the bike is fully tested and ready for a paint job.

I build, sanded and painted the box (with some big help from my 5 year old daugher - no kidding).

I took the bike for a spin and pictures while the box paint was drying.

[artur elias]

IMG_2753.jpg

[Juankixote]

Hey everyone, check out this cargo bike i just built in Detroit. i'm gonna put an electric motor on it soon!

[artur elias]

Hey everyone, check out this cargo bike i just built in Detroit. i'm gonna put an electric motor on it soon!

That looks NICE!

Do you have any pictures of the building process?

We could get this thread going at last.

[kalliergo]

Yes! What Artur said.

Tell us/show us how you built it, please.

[Juankixote]

Yes! What Artur said.

Tell us/show us how you built it, please.

I'd be happy to do that. I'm building 4 of them at once right now. I only get to work on it sometimes because I work on them when I'm not working at one of my 4 jobs. I will send regular updates with photos that describe how I build them.

more soon...

-Juan

[randomgear]

Artur, Impressive and inspiring!
It looks like your next job is building a super heavy-duty kickstand.
I hope you get it painted up, it's going to look fabulous!
You and Juan might be in a race to finish.

[artur elias]

Wow! You working on 4 jobs and building 4 Long Johns? Don't tell me you have 4 wives too! ;-)

[artur elias]

Artur, Impressive and inspiring!
It looks like your next job is building a super heavy-duty kickstand.
I hope you get it painted up, it's going to look fabulous!
You and Juan might be in a race to finish.

Thanks!

I may loose the race for the paint job, but I already (more like finally actually) have a decent flickr album on the build of the box bike.

http://www.flickr.com/photos/2376346...th/7262603888/

I'm in the process of up loading more pics and adding descriptions - both Portuguese and English text!

It's not a tutorial; that would be too complex to put together. But it should give folks a good insight in the process of designing and building.

I really hope it serves of inspiration to many others.

If I did it, anyone can do it. I mean it.

http://www.flickr.com/photos/2376346...th/7262603888/

[artur elias]

This is unbelieveble.

The flickr album with over 70 carefully selected photos and bilingual text is GONE.

There is something VERY weird about the way the iPhoto editing software interacts with the flickr page. I did something while working on iPhoto that I'm not even sure what it was - now I've lost several hours of work. Oh my, I should go to bed.

[n609mike]

I recently started building my own Cargo bike. Mostly based off Tom's design and the Cetma bike. Instead of the typical mounted box I plan to use the chassis from a kids trailer. I hope to be riding by the spring. The goal is to end up with something like this.
http://www.longjohn.org/galerie/img/...din_640_01.jpg

[MrRickyReno]

What materials (metal) are you guys using for these bikes? Just whatever is available at the local steel distributor or ordering tube sets like Nova Cycle has?

I built a cargo bike in the past based on Tom's Cargo bike designs. His instructions definitely work but I found it to be a bit too flexible until I built the cargo area into a steel framed box. I will try and dig up some pics sometime and put them on here.

MrRickyReno