He reckons it costs about $10,000 a year to maintain and insure a vehicle of a reasonable standard - too much for someone on minimum wage.
"I felt like I was going to work to pay for a vehicle so I could go to work."
He's got lots of other reasons for using a bicycle. One is exercise.
"I just think of it as gym time."
Another is to avoid burning fossil fuel and preserve the environment.
He says you see more when travelling a slower pace, and you hear more than people in cars. It's also more social - he's often stopping to talk.
"You are deliberately living life at a slower pace, in a way."
He doesn't ride just for pleasure, but gets a lot of pleasure out of riding - especially on the path through Kowhai Park and the cycleway to North Mole.
He rides a mountainbike because they are studier. He used to buy $100 ones, and accept that one or two a year would get stolen.
Then someone gave him a good women's bike. He swapped it for the good man's bike he is riding now. It has about 20 gears, but he still walks up the steepest hills.
He has expensive rain gear to get out in all weathers, and doesn't like wearing a helmet. He used to carry everything on his back in a heavy pack, but now uses a carrier and saddlebag instead.
"It's made life so much easier and I wish I had done it a long time ago."
He'll sometimes sling large heavy objects over the frame and push his bike along to carry them. His first television got up the hill that way.
If he has to go out of town Mr Hewson uses public transport, or hires a car.
There are places he doesn't like to cycle. He won't ride Victoria Ave when it's busy, because it's narrow and cars can't see cyclists as they back out. He'll only cross the Town Bridge by biking on the footpath. He wears a high-vis vest if he has to bike in 100kph zones.
In general he'll avoid cycling in traffic. He prefers Whanganui's shared pathways through parks and reserves, with water and trees.
"People and bikes are a better mix than bikes and vehicles."
Cycling silently up behind people, Mr Hewson will give a little cough or say "Excuse me" - to avoid giving them a fright. When cycling on footpaths he gives pedestrians the right of way.
"I don't want to do things that make a sensible way of getting ourselves around have a whole heap of rules around it. The more courtesy you show the less likely it is that that's going to happen," he said.