I'm sure it is hard for your wife to trust the boy will be safe after your accident, but riding on roads and riding on a cycle path are very different. I think you may need to take it in baby steps if you are to keep her on board. Its easier where I live because half the population cycle, everyone takes toddlers and babies on bikes, trailers, trikes etc. If its any help, the only accidents I know of here were to a child trailer behind a bike (terrible for visibility, we never used them) and a friend who caught something in his wheel and they went over: child was wearing a helmet and was fine. Generally road users are much more considerate to bikes and trikes with kids on, they used to stop on main roads and let me out when I had a tricycle. Up front child seats look safer to non cyclists because you have your arms round them. Also a nice stable hybrid or mountain bike will look better...can you fit a child seat on a road bike?..never fitted mine well and gave terrible wheel judder when starting, horrible