aiiii. Egypt is ok, Northern Sudan fine. But the run through Ethiopia to Kenya is a dodgy to say the least. Once you are away from the border with Ethiopia and Kenya the rest of the trip would be fine.
Maybe you could skip the Sudan-Ethiopia section. Uganda would be a cool detour but can you climb hills?
Just spent a month travelling with a landrover (landy) through east africa. several times i thought about cycling, but the roads in africa are a death trap.