Originally Posted by
merlinextraligh
IIRC, one of Psimet's team mates races with one arm. I'd PM Psimet, and see if he can put you in touch. Likely a good source of both ideas and inspiration for your son.
+1 on this. I'm pretty sure I saw photos of this guy on PSIMET's team page, but it looks like that page is down right now. I remember trying to look at the guy's bike to see how it was set up and I think the brakes were tied together to one brifter, but not sure. I'm sure PSIMET would point you in the right direction, he's pretty active here.
Also, reaching out to Shimano on the DI2 sounds like a good idea also, but I could see them hesitating because of liability issues (that kind of stuff really sucks in situations like this).