I read on your site that bikes with low trail are better for carrying weight on the front. It didn't really sink in until I built my shopping bike. I guess I had to learn the hard way.

http://cgi.ebay.fr/ancien-porte-baga...item3361d04244

Check out this one

There are a couple of those same racks on US ebay currently.

Not the prettiest rack. It looks like a medieval torture device.

I think you'd need a fair bit of force to snap an m5 bolt... one calculator gave me 11345 newtons which seems like a lot. It's a hard unit to translate into "everyman" terms. I've carried a few ridiculously large items on my bike and it was hard. I've done heavy things too, about 25kg tops, but as everyone else mentions handling of the bike is a far greater concern.

Very cool rack. It looks like it'd be easy to build if you have a bench vice and an adjustable wrench and some good drill bits.