Canadian-based Gerard Louis Robert, 67, who had won 24 world masters titles during his career, captured four gold medals at the 2016 UCI Masters Track Cycling World Championships in Manchester last October, winning the sprint, scratch race, points race and team sprint events, along with a silver medal in time trial.
In the sprint, he relegated Claxton to second, the sixth time Robert had beaten the Kiwi for gold since 2014.
But soon afterwards, he was notified of a positive drugs test taken five weeks earlier during the Quebec track championships in Canada. Robert had too much testosterone in his body - his test had returned seven times his natural level.
Initially, Robert received a four-year suspension, but when he appealed, it transpired that this was not his first offence - he had also been sanctioned in 2009 - so his penalty was doubled.
These events have left Claxton, who manages a South Auckland real estate company, more than a little stunned by the intrigue of international sport, even at his advanced age.
"I met Robert for the first time in 2014 and he won everything. There are five events in our category and he won them all, including all four sprints in the points race, and broke two world records.
"I remember thinking this guy was amazing, just astonishingly good. A few of the other guys who knew him well ... there was like a nodding of the head and I wondered if there was something I didn't know.
"Honestly, I just didn't want to believe that he was anything other than an astonishingly good athlete."
Drug-taking is obviously not confined to just aspiring Olympic-level athletes. Drug Free Sport NZ and the World Anti-Doping Agency conducted a testing programme during the recent World Masters Games in Auckland.
The age-group ranks are filled with former high-performance competitors who have made a lifestyle out of success and sometimes still make a living from their continuing achievements. Ironically, Robert's masters exploits were subsidised by his work as a role model for healthy living.
"It's surprising, it's alarming ... I was shocked and dismayed," says Claxton. "I went through a whole range of emotions when I found out.
"I thought of all the time, all the money, all the effort I had put into competing at the world championships over the years.
"I had a couple of dark days when I found out about Robert and wondered why I was doing it."
When he learned of his rival's plight, Claxton began a process to claim his rightful rewards - he will also collect a bronze medal from the points race. Official notification from the Union Cycliste Internationale arrived last week.
"[Robert] has messaged me, saying he is a man of integrity and protesting his innocence, but my honest feeling is that he has probably been training dirty and racing 'clean'. I suspect he's been on the juice and just didn't expect to be tested at that event."
Claxton, who took up cycling for his health in 2004, has a previous world title to his name - he won the individual pursuit in his first championship race in 2013 - and now has a second. These latest revelations suggest he probably should have had many more in the intervening years.
With this year's world championships scheduled for Los Angeles in October, Claxton is now training to defend his new crown and perhaps add a couple more.
At least, this time, he will have one less obstacle in his path to the top of the podium.
