"It's alright for runners, it's only on your shoes, but with us it's on your wheels and on your gloves. It happened to me once before and it just ruined my day," he said.
Robbie plays for the Waikato wheelchair rugby team and the national team, the Wheel Blacks.
He said his own team would be taking part in the 5km and hoped to rope some of the Wheel Blacks in from Auckland.
He said others should not be afraid to sign up.
"Just take your time and have fun - for us it's more of an inclusive thing than a race."
Despite this, he said his teammates would be racing for bragging rights.
Robbie has been in a wheelchair following a bad tackle during a rugby game six years ago, when he was 24.
He said he had taken part in Around The Bridges previously but he had not heard of any other wheelchair marathon events before.
Event organiser Lyn Harris said the event was quite unique, having heard of only one other wheelchair marathon event in New Plymouth.
She said the race would run from Flagstaff Park, around Discovery and Resolution Drives, and end in the park.
"It's all on the footpath, and we're going to have a lead cyclist for safety from cars backing out of driveways and that kind of thing," she said.
The race will be timed so wheelchair racers will come in after those on foot.
Lyn said she had one piece of advice for those thinking of entering: "Don't think about it, just do it."
The events will be held on October 4 at Flagstaff Park. Other events include a half marathon run/walk, a 10km run/walk, a 5km run/walk and an obstacle course for kids.
For more information or to sign up see www.hamiltonhalfmarathon.org.nz