Nayna.

At half past five in the morning, when Nairobi hasn't yet decided what it's going to be today, Nayna is already on the road. The Honda CB125 sounds the way an old bike sounds when someone has looked after it well: steady, a little hoarse, without complaining. She's heading to Wakulima market. Not to buy fruit. She's going for flowers.

She buys whatever there is. Red if she can. A small bunch, 150 shillings, sometimes 200 if the man at the stall reads on her face that she needs them more today. She carries them in her left hand, pressed against the handlebar, while she weaves through empty matatus along Haile Selassie Avenue. By a quarter past six she's on Lunga Lunga Road, the industrial part of South B, opening the workshop's blue gate with her free hand. The first thing she does is put the flowers in an empty oil can on the workbench. Then, chai.

She started doing this three years ago, shortly after her grandmother died. She didn't plan it. She was passing through the market, saw a bunch of carnations, stopped. She bought them without knowing what for. She put them in the workshop. The next day she went back. Three years later she still doesn't know exactly why, and she's stopped asking herself. If anyone asks, she says: "Because I like it." If they ask why she likes it: nothing. Silence. The flowers are there and the workshop has flowers and that's all.

Nayna doesn't shout. She doesn't argue by raising her voice. She doesn't slam doors. When a customer tries to haggle after the work is already done, she lowers the volume. She speaks more slowly. Shorter sentences. "The price is the one I said." Silence. "That's it." The customer pays.

There's a sound she makes when something goes well — an engine that starts up clean, a gasket that fits first time, the mid-morning light coming in through the workshop door on a Tuesday in July. It's a low hum, almost a purr, that comes out of her chest without her deciding it. Mwangi, the apprentice, calls it "Nayna's engine". She doesn't know he calls it that. Or she knows and says nothing. With Nayna you're never sure how much she knows about what's going on around her. The answer is usually: more than you think.

And there's another sound, rarer: a click of the tongue, dry and quick, just before she delivers a technical verdict. After the click, the solution.

The workshop is called NAYNA MOTORS. A hand-painted sign over the blue gate. The name has no logo or design: it's white paint on sheet metal, the letters slightly uneven because she painted them herself one Saturday morning with a hardware-shop brush. Inside: a long workbench, tools hung on wooden boards, a compressor she bought before a fan, a ficus in one corner and a cat that sleeps on the rags. The cat belongs to no one. It turned up five months ago. Mwangi calls it Boss. Nayna puts water out for it and hasn't given it a name.

South B is like that: workshops, hardware shops, food stalls, red dust when it doesn't rain and red mud when it does. Lunga Lunga Road is the industrial artery. Fifty metres away is Njoroge's workshop, where he repairs trucks and sometimes brings her ugali from his wife. Three doors along, Mama Amina's chai stall, where Nayna has breakfast every morning: a cup of chai, a mandazi, 50 shillings, standing, no conversation. Mama Amina doesn't ask. She serves. Nayna drinks. They both know that if one day Nayna doesn't show up, something is wrong.

Eight to twelve bikes a week. Most are boda-boda — the 125 cc motorbike-taxis that move half of Nairobi and break the way anything breaks when it works 14 hours a day. Punctures, brakes, chains, clutches. And every two or three months, something better: an old bike someone wants to bring back, or a crashed one Nayna buys at auction to rebuild and resell. She works on those projects at the end of the day, between half past four and six, when the light still comes in through the door but the customers have stopped coming. It's the part of the day she likes most.

She was born in Athi River, a dormitory town south-east of Nairobi that has spent twenty years undecided about whether it wants to be a city or stay a stopover. Her mother sewed in a textile factory. Her father repaired trucks on the Nairobi-Mombasa road, the A109, and spent more time under a chassis than at home.

He didn't teach her mechanics. What he did was not stop her. Nayna would sit beside the truck while he worked and pass him tools before he asked for them. By ten she could tell a diesel from a petrol engine by the sound of the start. At fourteen, a tanker truck ran over her father's left foot. He didn't lose it, but he could no longer work under a chassis. Her mother started doing double shifts. The money changed.

At fifteen, Nayna was repairing the neighbourhood's bicycles. At sixteen, boda-boda bikes. At the front door of the house, with her father's tools, which he no longer used. He watched her from the window. One day he said to her: "Learn to do things properly or don't do them." It's the longest thing he has ever said to her about mechanics.

At eighteen she finished secondary school and left for Nairobi. She worked 14 months in the workshop of a man called Kamau, in South B. Kamau was competent but unfair. He docked 3,000 shillings from her pay for a socket wrench he himself had put away in his own drawer. Nayna finished the shift. She didn't come back the next day. Or the day after.

The three months that followed were the worst. She repaired bikes on the pavement, with no workshop, with four wrenches and a screwdriver. The boda-boda riders paid her in cash, sometimes in kind: a helmet, half a tank of petrol, a lunch. She didn't eat every day. But every night she wrote down what she'd earned in a squared notebook.

A boda-boda rider called Ochieng sold her a wrecked 2008 Honda CB125. Eight thousand shillings — everything she had. Bent frame, dead engine, pitted tank. She rebuilt it in two months, at night, on the pavement, with a torch clamped between her teeth. When it started, it was the first time she heard herself make the purr.

With the money from the second rebuilt and resold bike she bought the leather jacket. In Gikomba, the second-hand market. A black biker, a size too big, the zip a bit stiff. She fixed it herself. She hasn't taken it off since. There's a tear in the inner lining, at the level of her left side, that's been there for two years. Nayna knows how to sew leather. She hasn't repaired it.

Her grandmother's name was Wanjiku. She sold chai and mandazi from a stall of tin and wood beside Syokimau station, every morning from half past four. The stall smelled of cardamom, boiled milk and dust from the road. Nayna went after school. Wanjiku taught her two things: to tie a scarf around her neck —"for the dust and so they know you work"— and not to speak unless she had something to say.

Wanjiku died on a Tuesday in August, at 74, while preparing the morning chai. A heart attack. Nayna arrived twenty minutes later. The first thing she did was close the stall. The second was take the scarf from her neck. Red with black spots. She tied it around her own. She hasn't taken it off since.

Sometimes, when she isn't expecting it, a hit of cardamom reaches her — someone cooking at a nearby stall, a chai somewhere that isn't the usual place — and her throat closes for half a second. Then she carries on.

She works the way a cheetah hunts, though she would never use that comparison. Well, not hunts — repairs. But the pattern is the same. Bursts. She can spend four hours straight on an engine without lifting her head, without eating, without speaking, her hands moving with a precision that looks rehearsed but is accumulated instinct. And then she switches off. She sits on the workshop's red stool, drinks half a litre of water in one go, stares into space for five minutes. If it's been a long day —three bikes finished, a tricky diagnosis— she's capable of closing the workshop at midday, taking a matatu to Naivasha and sitting by the lake for three hours watching flamingos. On Monday she comes back as if nothing had happened.

Those who don't know her think she's erratic. Those who do know that's how she works: first she burns, then she cools down. If she doesn't cool down, her hands shake. And if her hands shake, she doesn't work. Not because she can't — because she refuses to do something badly.

Mwangi learned that fast. He's been at the workshop eight months and already diagnoses punctures and brakes on his own. He's nineteen, quiet, and watches the way Nayna watched at that age. She doesn't tell him "good job". She keeps giving him better tools. He understands.

She lives in Syokimau, the southern edge of Nairobi. One room in a three-storey building: bedroom, kitchen-corridor, bathroom. The shower takes forty seconds to bring hot water. Nayna counts them. What matters about Syokimau is what lies beyond it: the motorway, and then the plain. From the building's rooftop, if you go up with the neighbour's chair (Nayna doesn't have a chair of her own), you can see the whole horizon. A sky of a width that doesn't exist in central Nairobi.

When she needs to really disappear, she takes the CB125 south. Past Athi River, past the petrol station, turning where the road ends and open land begins. There's nothing. Grass, acacias, sky. Sometimes zebras. Nayna parks the bike, sits on the ground and looks. An hour, sometimes two. She doesn't think about the workshop or the rent or the Yamaha. She doesn't think. She looks.

The Yamaha is a 1985 SR400 she bought at an auction of crashed bikes. Seized engine, straight frame, incredible chrome under the dirt. It's been stripped down at the back of the workshop for eight months. Each part cleaned, photographed, catalogued. Some she's had made to measure. She's in no hurry. It isn't for sale. It's the first bike she's restoring for herself.

The workshop has a problem Nayna doesn't look at head-on: the land isn't hers. The owner raises the rent every year. The area is going up in value. One day he'll come to tell her he's going to build apartments, and the blue sheet-metal shed will cease to exist. Nayna saves, but buying land in Nairobi costs what it costs, and she bills in boda-boda repairs.

Her father is still in Athi River. He walks with a cane. He spends his days at the front door watching traffic go by on the A109. Nayna sends him money every month and calls him on Sundays. Short conversations: "Are you all right?" "Yes." "Are you eating?" "Yes." She should go more. She knows it. She doesn't go.

Kamau is still 800 metres away, in another workshop on Lunga Lunga Road. They pass each other in the street sometimes. Kamau nods. Nayna nods. Nothing more.

The tools she uses every day — a set of old Gedore open-end wrenches, her father's wear marks under her own — aren't sentimental. They're tools. But if anyone touched them without permission, they'd know they'd crossed a line.

And the flowers are still there. Every morning, or every other morning, a fresh bunch in the empty oil can. The ones that wilt aren't thrown out until the new ones arrive. Sometimes, during the day, the petals fall onto the bench and end up among the wrenches and the bolts: red on metal, something alive on something that works.

Nayna doesn't see it as poetry. She sees it as her workshop.