Five-time Olympic cycling champion Sir Bradley Wigginssays he will be back rowing next year after his debut ended in disappointment.
The 37-year-old, who retired from cycling in December 2016, was competing in the elite men's two-kilometres event at the British Rowing Indoor Championships at the LeeValley Velodrome.
Wiggins has previously floated the possibility of going to a sixth Olympics, but this time as a rower at Tokyo 2020, when he will be 40.
But his inexperience in the event on rowing machines, such as those found in most gyms, was apparent as he paused early on, thinking he had false started.
He recovered his rhythm but shook his head at finishing in six minutes 22.5 seconds as Adam Neill won for a second successive year.
"Huge disappointment today!" he wrote on Instagram.
"Upon hearing a call in the background, I thought the race had false started so I put my oar down. School boy error but hey we live & learn as my plan was 6.02. Fantastic experience racing with everyone, will come back 12 months stronger next year!"
Neill finished in 5mins 48.2secs as members of the Great Britain rowing team filled the top five.
Wiggins was a respectable 21st out of 99 entrants, but left the competition area swiftly before leaving the velodrome soon afterwards.
He had set himself a target time of 6:05, said two-time Olympic rowing champion James Cracknell, who has been acting as a mentor.
"He'll be hurting a lot, but he won't leave it like that. He doesn't want to go out on failure," Cracknell said.
"He'll regard that as failing to achieve his target and he'll make sure he comes back and does it better."
It was all so familiar, except the result.
Wiggins arrived accompanied by his wife, Cath. The beard grown since the Rio Olympics, where he won his fifth gold in August 2016, was bushy and Wiggins appeared relaxed.
There are images of Wiggins throughout the venue, where he set the hour record in June 2015 and won the world Madison title with Mark Cavendish in March 2016.
One image of Wiggins and Cavendish was on a column next to the UK Anti-Doping stand which is present at events like this across all sports to promote clean sport. It was merely coincidence.
Wiggins railed at a "malicious witch-hunt" after UKAD last month ended a 14-month investigation into the contents of a jiffy bag delivered to him and Team Sky at the 2011 Criterium du Dauphine race without bringing charges. Team Sky and Wiggins deny wrongdoing.
But the episode - plus seeking and receiving permission to use a powerful corticosteroid before three major races, including his Tour triumph - heightened scrutiny on him.
The cameras of the assembled media were just two metres and a barrier away fromWiggins as he took his place on ergo 12 in heat four.
The physical strain of the effort was evident on his face and the hesitation showed Wiggins' focus was affected.
He had hoped to show his potential, albeit the discipline is a far cry from competing in a boat.
And he may be running out of time if Tokyo is really in his sights. Sir Steve Redgrave was 38 when he won his fifth gold in Sydney, but had a sporting lifetime of rowing behind him.
Wiggins has also missed the British Rowing open trials for 2018.
British Rowing chief executive Andy Parkinson told Press Association Sport: "It's not quite as simple as pulling some good ergo times and dropping yourself in a boat.
"Our trials process tries to be as democratic or fair as possible. We don't prejudice anyone coming into the system, but we don't provide any favouritism either."
Parkinson was formerly the UKAD chief executive, but would not wade into the recent controversies involving Wiggins.