Bakfiets Cargobike -- "Long John"

Tomscargobikes.com/BUILD_YOUR_OWN

 

On his website, Tom, tells how to make a simplified two-wheeled, Long John style, cargo bike.  So, while I am waiting around to get the metal to make the cargobox for the other bike ... I cut up a couple of spares and started making this bakfiet cargobike.

 

 This is from a little girls 20" bike.  The two tubes connected to the headset are cut off just short of the seat tube.  Then a wedge is taken out of the underside of the top tube so that it bends down parallel with the bottom tube ... narrower than 3/4" EMT tubing.

 

 5 ft. lengths of EMT are bent at a 45 degree angle ... on my bender that looks closer to 60 degrees ... but according to the compass that I compared the tubes against, it was only 45 degrees.  Maybe I need to re-check that and bend them some more ... hmmm??

 

 Anyway, they are placed in the gap alongside the tubes connected to the headset ... and the whole thing will be welded (at least tacked) together.  Now I need some 1-1/2" tubing to extend the headset on the rear frame.

Rear Section

Needing a rear section, I cut this out of a cheap mountain bike.

I think that I will use it at about this angle.

My concern is the angle of the seat tube.

Now I need tubing to make the box.

Cargotrike Plans = Cargo Trike Plans

All of the above measurements are in centimeters (cm)

The approximate inch (") measurements are: 

88 cm = 34-5/8"  (35)

127 cm = 50"

208 cm = 74"

50 cm = 19-11/19"  (20)

36 cm = 14-3/16"  (14)

62 cm = 24-7/16"  (25)

85 cm = 33-1/2"  (34)

The numbers to the right i.e. (35), are what I'd probably round the inch measurements off to.   That's what happens when you don't have a nice metric tape measure ...

 

Here's another view of a cargo-trike frame without the box

Of course this is a modern one with 20mm axles ...

it takes something heavy-duty like that to only support the axle on one end. 

To build one of these, the simplest would be to use a single-speed bike (donor, trash, or thriftstore) with a Bendix brake on the rear.  Cut off everything in front of the Bottom Bracket (BB) -- that's the part where the crank connecting the pedals goes through the frame.  And everything in front of the seat tube.  That leaves you with a rear triangle, seat tube, and bottom bracket all in one piece.  The cargo box and new main tube (which you will make) will connect to the front of the BB.

I decided to start on a cargo trike.  I needed something for the box out front to pivot on ... I looked at headset bearings and decided they were just too small.  So I cut a large bottom bracket off a bicycle that has a single-piece steel crank.  I cut most of the crank off on the side with the sprocket gear ... leaving just enough to hold the gear in place.  I figure to tack a thin metal plate to the single gear.  And that will then bolt to the frame of the box.  (see 6/17/11) Once I'm done welding the plate to the gear, I'll cut off the left-side crank leaving just a nub.  That should give me a good sized bearing.  And it will be serviceable ... to re-grease the bearings and change bearings & cups.

This unit will be the pivot base of the cargo box.

The box frame will bolt to the gear unit.

The steel tubing will be welded to it ...

the other end of the tubing will be welded to the BB on the rear of the bicycle.

Christiana Cargo Trike - Other projects have had priority ...

Most bike builders do their work in the summer.  Mine has actually been moved to the winter when it is too rainy to work on outside projects.  DMV has grounded my wife for awhile, so I am considering making a cargo trike that she can ride to the local store.  Something along the lines of a Christiana trike.

I'm thinking of using a bottom bracket from a single-piece crank as the pivotal foundation for the cargo box.  And attach that to the end of of a large square tube running from the BB that the rider pedals.  Although that round handle is nice, if you had more than one-speed, how would you replace a broken twist-grip shifter?  I'll have to think about that when I get to that point.  I think I'll start with the box frame and the rear frame and see what I have to do to connect them together.  :)