Patrick was racing in the Cycling Rotorua criterium race at Eastgate opposite the Rotorua Airport on Tuesday afternoon, which the club held every Tuesday. Soon after, he fell from his bike.
"Patrick and [his older brother] Clinton were known to turn up just about every week and just ride with their mates," Mr Clark said.
He said Patrick was riding in the front bunch with two laps to go. When he crossed the first finish line witnesses saw Patrick veer off and fall from his bike, which looked like he was having a heart attack, Mr Clark said. He said there were about 35 people at the race.
Mr Clark said nursing staff were at the scene and those at the National Fire Training Centre also came to try to resuscitate Patrick until the ambulance arrived 40 minutes later. Paramedics then spent a further 30 minutes before transporting him in a critical condition to Rotorua Hospital, where he later died.
Mr Clark knew Patrick quite well through mountain biking and having come from a high-profile cycling family. His brother Clinton is a professional cyclist, his sister Monique is an Xterra champion and his parents, Murray and Maryann Avery, are keen mountain bikers.
"I knew Patrick through mountain biking with my son, and when [my son] started mountain biking he looked up to [Patrick].
"He would be one of the fastest guys on a bike on a short sprint out of anyone I've seen, even his brother."
Mr Clark said Patrick would work for him cleaning vehicles in his school holidays and was "a great kid".
"He was just a fantastic young man, he was so very easy going ... he was just so friendly and everyone got on with him.
"He just had a fantastic personality."
At such a young age Patrick, who was affectionately known as Paddy, had achieved so much.
He had been a Waiariki Academy of Sport athlete, was an XC MTB athlete, had studied welding and fabrication, was a winner/podium NZ XC MTB U17, an NZ MTB Cup winner 2010 and had been part of the NZ MTB Team.
Sam Thompson, who was the academy's physical conditioner and responsible for the bike squad, said Patrick started there in 2009 as a cross-country mountain biker.
He was part of the academy until 2012 "but still very much what we call the WAOS [Waiariki Academy of Sport] family which is a close bunch of Rotorua athletes that stick together".
"I knew Patrick for the last three years where I took care of all his physical testing on the bike and gym training, he still has all the records in my bike-testing lab for any academy athlete and was one of the most talented and gifted riders I know."
Mr Thompson said Patrick had held the records for the past two years and he couldn't see anyone breaking them anytime soon.
"Patrick is known as the guy who was mates with everyone, who loved to have a good time and a laugh and everyone enjoyed being around.
"I will truly miss him and my heart goes out to his family."
A post on the Rotorua Mountain Bike Club Facebook page said all of this week's club races had been cancelled but "I am sure that we will be having a big race for Paddy in the near future".