Hoy, who has been undergoing chemotherapy, took the step of having a cold cap in an attempt to save his hair after his son Callum asked him if that would be a side effect of the treatment.
He said it was like your head “being in a vice”, during all six rounds over 18 weeks and said it was the most painful procedure he had ever been through.
“And I’ve got a very high pain threshold,” he said.
He said he suffered such a bad allergic reaction to the chemo in round two that the session went from two hours long to four.
The impact of the treatment left him “absolutely broken by the end of it”.
Back in February Hoy said on social media that he had been diagnosed with cancer and that his treatment was “thankfully going really well”.
He added then: “I’m optimistic, positive.”
Sir Chris Hoy training on the track with the British team in 2010.Credit: Wayne Taylor
The father of two, whose children are 10 and seven said he originally went to the doctor in September last year.
He thought he had suffered a shoulder strain because he was “getting a bit old for lifting heavy weights”.
It was discovered he had a tumour in his shoulder and a further scan uncovered that the primary cancer was in his prostate, which had spread to his bones.
There were tumours in his shoulder, pelvis, hip, spine and rib.
Hoy, in a memoir which he has written in the past year, said: “[You are told] one sentence that some person you’ve never met before has just told you.
“And in the space of one sentence, just a collection of words, your whole world has fallen apart.”
His memoir is due to be published next month.
Reveals his wife has been diagnosed with multiple sclerosis
He also told how his wife Sarra has also had to deal with the diagnosis that she has a “very active and aggressive” type of multiple sclerosis following a scan last November.
She made the devastating discovery after she started to suffer a curious tingling sensation in her face and tongue.
Hoy said the biggest challenge was having to tell their children Callum and Chloe but he was able to find perspective and positivity.
“I’m not trying to pretend that every day is amazing. But I have genuine moments of joy… I’m back to my old self,” he said.
Chris Hoy after winning the Men’s Sprint at the 2008 World Championships.Credit: AP
Sir Chris told The Sunday Times: “As unnatural as it feels, this is nature.”
He added: “You know, we were all born and we all die, and this is just part of the process.
“You remind yourself, aren’t I lucky that there is medicine I can take that will fend this off for as long as possible.”
Hoy, who was a pundit for the BBC covering the Paris 2024 Olympics in the summer, was such a dominant force in sprint cycling that he had won six Olympic, 11 world and 34 World Cup titles by the time he retired from competitive racing in 2013.
He is the third most-decorated British Olympian of all time, with six career golds and one silver medal.
Sir Chris said the diagnosis came as a “huge shock”.
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He wrote: “I have a bit of news. Last year I was diagnosed with cancer, which came as a huge shock, having had no symptoms up to that point.”
Sir Chris extended his “sincere gratitude” to medical professionals for their “amazing help and care”.
The Scot said: “While I’m thankful for any support, I’d like to deal with this privately.
“My heart goes out to the many others who are also going through similar challenges right now.
“I’m optimistic, positive and surrounded by love for which I’m truly grateful. As you might imagine, the last few months have been incredibly difficult. However, I currently feel fine.”
