Josh Quigley, 27, shared a picture of himself in hospital after breaking several bones and suffering a brain injury.
The motivational speaker, known as the Tartan Explorer, went viral on social media for speaking out on mental health issues after turning to cycling as a way of managing his own well-being following a suicide attempt in 2015.
The former Deans Community High School pupil embarked on his current world cycling attempt to beat depression and mark 365 days of sobriety in October.He wrote: "I got hit by a car in America. Got flown to hospital via helicopter. Fractured ankle, fractured heel bone, fractured pelvis, fractured ribs, pierced lung, fractured skull Issue with artery to brain, tube in my chest to stop my lung collapsing. Another obstacle to overcome."
His followers were quick to offer words of support and encouragement. Jo Shepherd tweeted: "Oh Josh I am gutted this has happened to you. You've done incredible things over the last few months, and have been an inspiration to follow. So glad you're alive and will recover. Best wishes."
Sandy Moir wrote: "That is quite a bump, I'm sure you have a tough head, take it easy, have a speedy recovery, and don't forget you are an inspiration to us all, and we are all thinking of you."
iJake added: "Devastating news, Josh. My very best wishes for your recovery. Not quite the end to the year anyone could ever have imagined. Stay strong. Get well."