here http://www.sudibe.de/articles/wheandhub.html is the classic formula for wheel strenght by Bill McCready of santana. I read about the benifits of reduced dish in articles by Frank Berto in the 70's In 1980 I stopped in the bicycle shop run by Ron Boi in chicago who was also a custom builder. His personal bike had an 18 spoke back wheel built with a crowsfoot pattern with campagnolo hubs and a special order 130mm over locknut campagnolo axle. The wheel had no dish and a suntour ultra six freewheel with an extra gear welded to the back of the largest cog. Mr Boi was an amature racer who weighed about 175 pounds. He reported no problems with that wheel. I tell people this and am accused of being a troll. Since then I have built all of my wheels with zero dish here http://share.ovi.com/media/currentre...resident.10016 is one. For full disclosure I am a tourist not a tandemist the back wheels carried 150 to 165 pounds. One the other hand I have put 70000 miles on these wheels and my beta testers have done an additional 10000 miles. I have broken one spoke the one with the N stamped on the head and cracked one rim a syncros XLT. I do however bend a lot of solid axles. I understand basic strenght of materials and I think I know where Mr McCready is comming from with his formula. First the easy part if you have a flange that is 22mm from the center line of the wheel and you usa a 10mm wider axle so that the flange is now 27 mm from the centerline of the wheel it will make the wheel stronger by a factor of 27/22 due to the sideways pull on the rim this is not the correct formula the correct formula involves vectors and trig but it is a good approximation. If you have a hub with 22mm from one flange to the centerline and the other is 32 mm from the flange this reduces the tension on one side of the spokes by a factor of 22/32 again this is not the correct formula but it is a good approximation. A few spokes on the bottom of the wheel loosten under a load you can actually see this on a highwheeler bike. If one half of your spokes have one half tension of the other half it effectively reduces your wheel strenght by one half. Use both of these formulas together (22/27)*(22/32)=.5601 this is the calculation for Mr Boi's wheel a standard wheel was only .5601 times as strong as his wheel with the wider dropouts letting him use only half as many spokes. The formula works for me it seems to work for tandemist.