The spotlight at the Paralympic Games in London has not been on the athletes alone but also on the remarkable technology that helps them compete. In London, engineers, volunteering for a charity called Remap
, are developing Olympic technology right in their own backyard.
In the garage of his home just outside London, David Sheffield is working on the prototype for a wheelchair suitable for Paralympic athletes. Working with him is former engineer Doug Watt.
They are among some 1,000 people who volunteer for the charity Remap, designing technology that helps disabled people. They do it in their own garages, for free, and usually using their own materials.
The wheelchair they are working on now is designed to fit shot put thrower Shaun Sewell. It is also adjustable and will be used as a template for future athletes, as David Sheffield explains.
"We were asked to make a chair that was totally adjustable in every way so that we can use it not just for Shaun but also for other athletes. And then we can find the exact positions for the way they sit, the way they hold the pole, the way they lean back and so on. And then once that is all set up we will then make them a chair just for them with those dimensions and those features," said Sheffield.
Now in his 30s, Sewell has been using a wheelchair since he lost the use of his legs in a motorcycle accident 13 years ago.
He almost made it to the 2008 Beijing Paralympics but his plans were disrupted when he contracted life-threatening septicemia. He says the past years have been a challenge.
"The journey that I have had as a competitive athlete has not been easy at all," he said. "Trying to find a coach, trying to find a gym that can help you in the way that you need help, because there are certain things that I am unable to actually do by myself. If you want to get into throwing as a disabled thrower, you find a welder's yard. And you and that welder come up with an idea for a frame, and it's quite bog standard."
That is a world away from the new wheelchair Sheffield and Watt are designing for him. They have carefully taken all his measurements so the chair is the right fit for his body. They have also spent time watching him throw, so they know how his body moves and where extra support is most needed.
Sewell says he is intent on making the Paralympic Games in Rio de Janeiro four years from now. The new chair, he says, will help him get there.
"I believe it's going to make a huge difference," he said. "I'm throwing really well with the frame I've got now which is not right for me, so having something that is right will only improve my distance."
Peter Parry, chairman of trustees at Remap, says its volunteers have built devices for three athletes competing in this year's Paralympics.
He says it is not like the other work the volunteers do - not least because there's a large book of rules about what technology is allowed.
"We can help them support themselves," he said. "We can provide them with the pole - as you saw - to help them balance their body. But what we cannot do is have things like springs or hydraulics, which would give them an unfair advantage. Because then it becomes a battle of who can make the best device rather than who can be the best athlete."
Parry says with technology there can be the temptation to cheat - as with performance-enhancing drugs. But luckily, he says, with wheelchairs, spotting any unfair advantage is easy.
"It is relatively easy to check," he said. "For instance, the pole that Shaun holds has got to be rigid. It's not allowed to bend and give him any spring. Similarly, the back of his seat has got to be rigid. These are fairly objective tests, which you can put on. Really where the problem is likely to come is in things like the running blades, where the amount of force on those is enormous and the use of composite laminates is both expensive and give the advantage by using different materials for a different person."
And, he adds, with technology advancing it could become a more difficult terrain to monitor.