Progress is being made. Last night I extended a Bike Friday 20″ fork to have a very long steerer. I might end up redoing it, I”m not very happy with how my brazing went.

I encountered your blog post here, and the project looks awesome.

I still haven”t finished the updates to my cargo bike that I”ve been planning, but it should be done in the next couple of weeks. Since you are working on this, I”ll give you the advance word on a product I found and a theory I”ve been pondering.

First, this pizza delivery bag is super cheap and should be very effective as a rack-top bag for the cycle truck:

http://www.deliverybags.com/product_large-pizza-jacket.htm

It is made of a kind of synthetic canvas treated with something to make it at least somewhat water repellant; it has 1″ thick insulation fill on all panels which acts as a cushion; it can be folded down when empty, or compressed with straps around the load; and it looks fine.

Second, I have a theory that connecting cargo loads with too much rigidity contributes to shimmy. I experienced the worst shimmy ever on the cargo bike when I strapped 35 pounds of newspapers to it very tightly. The unbraced cantilever seemed to find a nice oscillation that made it shimmy crazily even with both hands on the bars.

I suspect that similar loads attached less rigidly, that is, with the ability to slide a bit to avoid resonant effects, could eliminate this problem. I look forward to trying it once I have tailored the pizza bag to fit on the rack.

I came to this theory after carrying a giant cardboard box home on the cargo bike with a bunch of weight in it loosely, and found that it did not shimmy at all.

I suspect that engineering in some looseness with cargo carrying could benefit a lot of bicycles that have this problem, although one wants to avoid designing things that are subject to fatigue failure.

Cheers,

James Black

Although the picture doesn”t show it, the other half of the old downtube would probably be left in place butted into the top side of the “cargo” tube? Without another triangle there, the joint in the middle of the cargo tube would be under a lot of stress.

The schwinn cycletruck is a great place to update I think.

Back in my past I had decent luck with angle iron and 2×4 fixturing so when in doubt, do.

Adam — This will still be smaller than most of the bikes that you mentioned. Those are some of my favorite types of cargo bikes though. At one point David Wilson was talking about getting the James Black Cargo Bike built as a production item. It would be really cool if that happened.

The U-brake is going, I”m going to braze on canti studs and use V-brakes. Actually, the U-brake studs will probably stay there, but I doubt that the brake will. Maybe I”ll turn it into a parking brake.

What’’s the reason for not building the main rack tube horizontal? Or, will the rack itself be horizontal, just this support tube is not? I”m guessing most loads don”t care if they”re carried on an angle, and it helps keep stuff on the rack, are there other reasons?

Oh -are you keeping the U brake on the chainstays?

My original plans also were simpler and kept the downtube in place. However I thought more about it and thought that it would be good to cantilever the rack off of the frame. This is the simplest way to build a James Black/David Wilson style cargo bike that I could think of.

Even for a simple design I think you”d want to replace the head tube. Mountain bikes typically have slack 71 degree head tube angles that aren”t going to be ideal for large loads. I also wouldn”t want to sleeve and extend such a crucial tube on the frame.