The bakfiets is an incredible machine.  I was turned onto these bikes by Josh Muir of Francis Cycles.  It is the ultimate for every day errands, grocery store trips, and hauling children around.  It fits in the bike lane, it is nimble and quick, and is a pleasure to pedal.  I am loving it and seriously think a car free society will rely on these puppies in addition to normal bicycles.

After trying a trailer, backpack, and rear seat, I think the bakfiets is the best way to transport children. Although there are some concerns...(see step 6 for some ideas on the safer ways of placing children in the box).

This instructable is all about how to design and build a bakfiets style cargo bike.  The design tips apply to any bakfiets style cargo bike and there is no need to build it out of bamboo.  I like the ride quality and uniqueness of bamboo.  However, if I do it all over again I might use steel... Building a bakfiets is like building three normal bikes.  The amount of epoxy and sanding seemed to add up.  I think my next bike may be fillet brazed steel.

Here is the breakdown:

Cost: $600 (including components - mostly used)
Time Frame: 4 months

Useful links:
Larry vs. Harry Bullit
the dimensions of the bullit
Francis Cycles
Tom's Cargo Bikes
My Instructable
Bamboo Bike Blog

Sources for materials:
Epoxy: West Marine (I used West Systems but I think I should have tried this: http://www.entropyresins.com/products/super-sap-clr - half the price of West System 105)
Bamboo: local bamboo nursery
Drop Outs and Tube: Nova Cycle Supply : http://www.cycle-frames.com/bicycle-frame-tubing/home.php

The art of building bamboo bikes has really come a long way.  I have realized that my technique from 2008 is probably not worth emulating.  I strongly recommend that you look at the Bamboo Bike Blog and other instructables for the next level of building with bamboo. I particularly like this instructable by kentdvm:

So let's get started!

Step 1: Design Geometry

In designing a bakfiets there are few constraints when it comes to size and shape.  There are however some real constraints - you don't want the pedals to hit the road when you go over a small bump or turn the corner.  You also don't want the basket to hit the road when you turn the corner.  Width is another issue.  I went with much the same width and geometry as the bullit.  Steering is another big design consideration/constraint.

The design concept of the bakfiets is that you have two wheels (which makes the bike nimble and easy to steer and ride) and a low center of gravity which makes it very stable.

Wheel size - smaller theoretically means more stability.  I went with a 20" wheel in the front and a 26" wheel in the back.  I have heard of some people using a 20" rear wheel, although I have never seen this.  There are a few different sizes that are all called 20".  The front wheel I used is a 406 mm rim diameter. This seems to be the most common 20" size and there are a lot of bmx tires and recumbent tires readily available.

Bottom Bracket Height - 265 mm - this should probably be 30 to 50 mm higher.  When I drew the bike out I had this as 290 mm but somehow in building the bottom bracket came down.  This may have something to do with skinny tires I ended up using.  I do get pedal strike when turning corners sharply or pedaling over speed bumps.

The basket is pretty low (150 mm).  The lowest point however is the bottom of the steering tube (120 mm)  I am pretty sure this has never struck a bump in the road.

The bike is 580 mm wide.  This is no wider than many mountain bike handle bars (600-700mm).

Below is the geometry of my bike as it is built.  So far the only issue with the geometry is the bottom bracket height - this really not too big a deal and I subconsciously keep my pedals up when going over speed bumps.  The bike may be unnecessarily long.  There seems to be a bit of spare room between my knees and the basket.

Another thing I did was slope the seat tube back to allow me to keep my butt on the seat and still have my feet reach the road.  This makes stopping and starting much more comfortable. 

I have long chain stays which are not really necessary.  This was a half baked idea to get more tire clearance by moving the wheel back.  (I ended up messing up a bit and don't have the tire clearance I would like.

I would design the bike to accept big tires even if you end up riding skinny tires. 

The bike is surprisingly upright in the turns and unlike a normal bike the bakfiets is steered with the front wheel and not by leaning over.  Because of this you almost always have to have at least one hand on the bars at all time and really need to to have your butt on the seat for stability.

It is slower but I am enjoying learning to take my time on the rides.  One big advantage has been the added effort required to get around.  My daily commute on my road bike is not much of a work out anymore.  Now on the bakfiets I am getting a workout again.  My 5 mile trip to work takes me just under half an hour on the road bike and just under 40 minutes on the bakfiets.

The attached pictures show the geometry of the bike and some ideas on design changes you can make if you go with cable steering instead of rod steering.  I chose rod steering and a very rectilinear design - this works particularly well with bamboo.  If I used steel I would definetly added some curves because curves are pretty.  Josh Muir's bikes are works of art.

Steering is discussed in more detail in step 3.
Ayasbek, i am in the proceed of replicating your design and have got to the point of drive testing it. There seems to be a wobble in the front wheel at low speeds, coasting. I was wondering if you had this problem too and how you corrected it? Any comments would be appreciated!<br>Thanks, Rob
<p>Hi Rob, I am so impressed you replicated the design. Well done! I am starting to think that the steering is the trickiest part of the whole design. I made a new box bike (out of steel this time) and changed the head tube angle to 80 degrees (almost vertical) and used a rake of about 45-50 mm. I think the steering is vastly improved but there is still wobble at low speeds (at least this is the feedback from other people I have asked to try the bike). I have noticed that steering at high speed is super stable and safe feeling. There appears to be a trade off between stability at high speed and stability at low speed. To make matters worse the steering response is going to change depending on the load in the bike. I think it gets much smoother with more weight. So here is what I think you should try:</p><p>1. Get used to it. I am not being sarcastic. It is amazing what your body and muscle memory can adapt to. Ride it for a week and see if you are still thinking about the wobble all the time.</p><p>2. Add a spring or damper to the fork. I believe the Yuba Mundo has a spring attached to the fork for this reason. The Larry v. Harry Bullitt has a small shock absorber (damper) as an optional add on to the fork. You might find the right thing from McMaster Carr or similar industrial catalog.</p><p>3. Change the fork to have less rake. This is a big step and will require some welding, etc. I would also research everything you can find on steering geometry and rake before doing this. The best option is to build a fork with adjustable rake so that you can find experimentally the rake that works best. Lots of work...</p><p>here is a blog where multiple forks were made:</p><p><a href="http://drewsminiblog.blogspot.com/2010/09/making-cargo-bike.html" rel="nofollow">http://drewsminiblog.blogspot.com/2010/09/making-c...</a></p><p>There is one more thing you should check - make sure your bamboo is not flexing and that the head tube is rigid in the frame. Frame flex might be a contributing factor...</p><p>Good luck and please let us know how you ended up dealing with this issue.</p><p>-Alex</p>
Alex,<br>Thanks for the reply. I will try it for a while as you say. I am planning to put up my own instructable in a couple months when I have the majority of the project finished. I will let you know here when it goes up if you want to take a peek.<br>Thanks, Rob!
I weighed the bike - 59 lbs. That includes the box.
that's great! mine (same desig, but made of steel: http://www.instructables.com/id/build-a-2-wheel-cargo-bike/ ) is approx. 10 lbs heavier and i bet it's not as strong as yours.
wow, congrats to this great project. somehow i don't dare to do all this epoxy-work and build my bikes from steel (see http://www.instructables.com/member/carkat?show=INSTRUCTABLES ). i guess the bike is much lighter than steel ones, which would make it definitely worth to learn to do it that way. anyway, thanks a lot for sharing!
Fun design! <br /> <br />I keep thinking of this as a wheelbarrow powered by a bike, not a bike with shopping cart sized basket on the front. Somewhat different purposes there, after all, it doesn't have mountain bike tires on it.... <br /> <br />I would have still gone with a pair of front wheels (which still control direction) as it would have been much better for stability all around. The turning radius should be very similar, with only a slight change in overall width. As they say, YMMV. A high-speed cargo bike seems a bit like a oxymoron. <br /> <br />I would also suggest to make at least one side panel easily removable or open like a door. Then you don't have to lift items (like rocks, firewood, grocery bags., etc.) back &quot;out&quot; of the basket, just take off the panel and dump it out. Much easier to sweep out the basket later too. <br />
You could also instead of just adding the reflective tape, add some small LED lighting on the bike. I have been I have been looking at small batteries from old Standby power supplies for computer and the battery in that is a great size to add to a bike like this. Also you could put a small solar panel on the bike to keep it charged while you are not needing the power.
Yes, Yes ans Yes! The top of the box is perfect for a solar panel. I thought about a solar panel lid so that when the bike is parked outside the cover keeps whatever is in the box safe and charges up the battery.
I don't see the advantage over a trailer. However, I see numerous disadvantages.
Well for one if your hauling kids you don't have to look over your shoulder to see what they are doing or know what they are pointing at when they say look at that. Plus it would be a whole lot more interactive. As for cargo I imagine it would be a matter of preference. I think in the end a cargo bike is shorter than a bike/trailer combo. Besides backing up would be a whole lot easier.
Awesome job.
I have long advocated for bambo for an engineering material..I once built myself a bambo leg brace that was almost weightless and performed flawlessly...This is where all things need to head..grow your own building materials!!...
Not the best Design but a realy cool idea. <br> <br>Thanks for the instruction

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