My 16 year old son has no fine motor movements in is right hand. All road bikes today have dual action brake levers as my son's bike does. We would like the left lever to control the rear dérailleur and the right lever to control the front derailleur. We can't switch the levers because then the thumb control will be on the wrong side of the lever. Does anyone know of a manufacturers that has the rear dérailleur controlled from the left or have any other suggestions?