Working in Albuquerque, New Mexico, Claire and Rory Flemmer saw a woman in a wheelchair trying to get up a ramp.
She was struggling and they stopped to help. Rory remembers thinking why did this woman have to struggle so much.
"It occurred to me then that this was actually wicked."
While the motor car has undergone many advances since it was invented, the wheelchair design is identical to that of 1900, he says.
The Flemmers now live in Palmerston North - Rory is a chemical and mechanical engineer and Claire is a mechanical and aerospace engineer. Claire is a senior lecturer at Massey University while Rory has retired from lecturing. They both have PhDs.
In 1988, while living in West Virginia, they started developing an improved manual wheelchair. Rory says the brakes have been rebuilt four times, and other parts rebuilt 10 times.
They are now seeking wheelchair users to test the patented chair. The next step is production and sales.
Claire says a standard wheelchair is very inefficient as you only have a quarter-cycle push, the rest of the action is wasted time getting your hands back to the starting position.
Using the same muscle over and over can also lead to repetitive stress injuries.
Claire says people in a wheelchair are in an absolute trajectory of dismal circumstances. Their world can shrink to their house as it is too hard and painful to move around and they also end up not getting enough exercise.
"It's just so hard for wheelchair users to go on outdoor paths that we very rarely see them."
Enter the Flemmer wheelchair which allows people to use their full arm stroke; it's like a gym for the upper body in a chair as users are exercising while driving the wheelchair.
While their hands are on a handle, that is not cold to the touch, users push forward, then pull back, using their full range of arm motion. However, while pulling back the chair continues to move forward.
Claire says this exercise encourages the muscles to grow and is using arm muscles in a balanced way.
"Your joints are happy, that is how they were designed to work."
Rory says using the chair burns more calories than walking, plus wheelchair users experience getting out of the house.
The chair has three gears - first to go uphill, second for travelling, and third on smooth paths. It can go the same pace as a reasonable jogger and has an anti roll-back system. The Flemmer chair is heavier and wider then a standard chair. Users can push a button to compensate for the camber of the footpath.
Its durability has been tested in the lab using a pneumatic cylinder. The Flemmers are also taking the chair around the block themselves as lab tests don't take into account factors such as footpaths with tree roots coming through, hitting a kerb or rock, or going through puddles.
The Flemmers are seeking 10 wheelchair users to try the chair and provide feedback. Ideally, they are after users who want to exercise and go outside. They expect the test will take 15 minutes with another 45 minutes giving feedback. Each tester will receive $100.
The Flemmers' design work has received funding from Callaghan Innovation, New Zealand's innovation agency.
The Flemmers are originally from South Africa. They moved to the United States, before settling in Palmerston North in 2005.
For more information about testing the wheelchair email email@example.com.