Simon Gould was found unconscious at the bottom of a very steep trail in the conservation park about 8am on Monday.

He suffered a critical but "isolated" head injury, a Queensland Ambulance spokeswoman said.

It is understood he was riding with friends when he crashed.

Mr Gould, from Wellington Point, was taken to the Princess Alexandra Hospital by ambulance but died about 9pm.

His teenage daughter Andrea, who sat by her father's hospital bed on Monday night, has paid tribute to her father on Facebook.

"I sat by your side for nearly 12 hours and even that wasn't enough time to say goodbye," she wrote.

"I love you so much dad and I don't know how I am going to cope without you In [sic] my life.

"I'll always be your little princess and I'm going to grow up to be the girl you wanted me to be and were proud of. I promise to look after Aaron and make sure he also grows up to be the man you would of been proud of."

Friends also paid tribute to Mr Gould, describing the sports enthusiast, who spent his weekends hiking, camping and running, as a lovely man.

"He was riding with a couple of other friends who tried all they could to help him," one friend wrote on an online mountain bike riding forum.

"I understand the response time from the ambos [sic] was very good in the circumstances. Unfortunately he was too badly injured and passed away last night.

"Simon was a lovely man who will be sadly missed by friends and family."

Police said it appeared Mr Gould had lost control of his bike while riding but authorities would continue to investigate the circumstances surrounding the incident.

Daisy Hill Conservation Park is considered one of Australia's premier mountain bike riding areas. It is frequented by riders, particularly on weekends.

The park includes at least seven designated mountain bike trails, as well as fire trails which are open to horse riders and trail runners.

Anyone with information is asked to contact Crime Stoppers on 1800 333 000.