I'm looking to build up a utility bike and was wondering whether anyone has any numbers at their fingertips. Two specs I am looking at right now, are the spacing on an Xtracycle into which the "rack" parts fit. I am thinking of the two horizontal tubes that carry the running boards. Any other fittings that are key. I am not thinking of a copy of the Big Dummy, but that format is probably as close to a new industry spec as one can get for that kind of bike. Seems like it would make sense to provide compatibility to Xtracycle parts.

The other spec I am looking for is for the tubing diameter in a cargo bike. Many of the small shop versions use a built up truss, and I might also. I have a bender than can bend 4130 up to 2" so I figured it would at least be worth while knowing what size the main tube is. Anyone have a Bakfiets and know what the dimension of the large frame tube is. I'm guessing a 2" .035" would work, might have to be.049 for a real workhorse. I'm a little leery of doing a freehand bend on that scale, because it is very difficult to correct if anything goes wrong. That is one reason the truss looks like an easier option.

I built a longtail for myself in the spring just to see what all the fuss was about. The whole thing is in steel and is completely integrated, including the "wings" for carrying heavy stuff low and beside the rack.

First, let me say that there is almost no such thing as too big. In fact, at 57" wheelbase and 38" long rack, I think the bike is far too small for some of the stuff I have personally hauled around... which at one point was at least 250 lbs of steel tubing, tent poles, lawn chair frames and angle iron for building more bikes with.

In hindsight I should have gone with an even longer wheelbase... approaching 70" so that most of the load becomes centered ahead of the rear axle. The reason I know this works is because I built a 94" wheelbase longtail to carry 12 rubbermaid tubs for a local delivery service. Because 8 of the tubs actually sit ahead of the rear axle, fully loaded, the handling is actually slightly better than when it is unloaded.

:)ensen.

Here are the Xtracycle frame specs: https://www.xtracycle.com/longtailtec...meStandard.pdf

And the spacing: https://www.xtracycle.com/longtailtec...ail_Dimensions

And all the other tech info you need to make a bike compliant to the Open Source Long Tail Technology: https://www.xtracycle.com/longtailtec....php/Main_Page