so another issue, continuing a bit the line opened up vincentny, the pressure on the wheels must be humongous. How long can those wheels last in this application? Of course, you could always turn to steel, but you might be damaging the surface you'd be moving on. Myself, I have no direct familiarity with either a-bike or carry-me and there is a chance that they satisfy impulse buying needs and not those of long-term use. Otherwise, clearly, congratulations on the design! Even if it works partially, it is a serious accomplishment. This balance is an interesting issue. Skaters don't e.g. continue on one skate only for too long, but then they need also to balance the forward-backward direction.
Why would it be any worse than what a regular bicycle wheel is subjected to? Except these aren't made out of thin branches (ie spokes) asymmetrically stretched (dished) several feet across.
Not to be rude, but I find it very strange how people's intuitions about things like small wheels, recumbents, etc are often so irrational. What could possibly make you think the smaller wheel would be weaker? Reality check: larger wheels are the ones that have to turn to steel
because they are weaker, but since small wheels are so strong they can get by just fine with polyurethane.