A man was found cycling on the M25 in Surrey after an app on his phone sent him there by mistake, police said.
Drivers saw the man on the hard shoulder near the junction with the M3 during rush hour on Tuesday morning.
Hannah Leonard tweeted: "My usual 40 minute commute to work took an hour and a half due to a cyclist on the m25!"
Surrey Roads Police tweeted: "Cyclist stopped and after a long conversation he has been safely removed with his copy of his ticket for £50."
The force tweeted that the man, who cycled "several miles" on the motorway, had been looking for a shorter route to cycle home from work.
"Phone app sent him on motorway so thought it ok," it added.
Further tweets from the force read: "Genuine mistake I'm sure but could have stopped at bottom of slip road! Most children know not to stray onto a motorway.
"Nice chap but unaware of the rules of the road, believed it ok to ride/walk on hard shoulder, struggled to see why not.
'Merrily cycling along'
Ben Newman saw the cyclist, who was wearing a black rain jacket and was on a white bicycle, between junctions 12 and 13 as he was driving to work at Heathrow.
"I was keeping an eye out for him, because I heard it on the radio," he said.
"You didn't notice him until you were right up close to him. He came out of nowhere.
"No-one could react to him until you were almost on his backside.
"He was merrily cycling along, like he was taking in the sights.
"I've worked at Heathrow for 10 years, I've seen some crazy stuff but nothing as crazy as this," he added.
Later, Sgt Phil Dix, from the roads policing unit, said: "It is extremely fortunate that there was a safe outcome and that the cyclist was not injured or worse - especially as he had crossed several slip roads coming off the motorway."
He said it showed why motorists needed to be alert and vigilant and added: "You never know what you may come across."
He urged all road users to use a common sense approach when using satnav, whether they were on foot, or on two wheels or more.
Dez Leach, Highways Agency operations manager, said: "Thankfully, this was a rare event."