A duathlon due to take place this weekend in aid of the #TeamGeorge campaign has had to be postponed.
Organisers of the event said this was due to operational issues that could not be overcome.
It is postponed indefinitely but organiser Tom Avery said he was hopeful of setting a new date in 2017.
Those who had signed up were due to be refunded their registration costs this week.
The event would have taken place on Saturday and included a 5k run, followed by a 25k bike ride and then a final 2.5k run.
The aim was to raise funds for the #TeamGeorge campaign, which helps Stamford teenager George Robinson.
The 18-year-old suffered a life-changing injury while playing rugby with his classmates in South Africa last year and is in a wheelchair.
But he has not let it affect his positive attitude to life and this week, he returned to Stamford School with younger brother Eddie to complete his final year. He hopes to go to university afterwards.