I was definitely in the frame for a Darwin Award, the prize for people who get killed by their own stupidity, and thereby improve the world's gene pool. I had weighed up the options for after Lyme Regis. I could follow the National Cycle Network's route, which zigzags inland through Dorset's finest lung-bursting hills for mile upon unnecessary mile. Or I could get on the attractively straight A35. I mean, how bad could it be?

Doh! Imagine the narrowest of two-lane highways, imprisoned in a canyon of 10ft hedgerows, that dives and twists into valleys, with blind, sweeping bends. A road used by a stream of speeding, tailgating lorries and coaches which, if the carpet of broken glass and wing mirrors is any indication, regularly clip each other in passing. I got off and pushed, and the stinging of the roadside nettles seemed like divine punishment. Footage will doubtless emerge on Police, Camera, Action! "Tuesday morning. Just outside Bridport. CCTV operators are alerted to some geezer trying to cycle on the A35. Muppet."

So I parted company with the lorries and took the road that runs high above the World Heritage site of Chesil Beach, with views beyond to Portland, its grey-marbled, sculptured cliffs like a set of molars in need of a good polish.

The barrier that closes the road across the Purbeck Hills when the army is using its firing range was up, so I pedalled on, past burnt-out tanks and bullet-hole-ridden target boards. Up and up the chalk downs I rode, glancing north now and then to the distant gun emplacements, waiting for the silent puff of smoke followed by the howling sound of incoming and another nomination for a Darwin.

At the top, I was moved to tears. For one thing, my big toe was agony: a stress fracture from the miles and weeks of West Country hills I'd just ridden. But more importantly, as I looked east, across the vast expanse of Poole Harbour and the New Forest beyond, there were no more hills. Nada. Flat as the proverbial pancake. I felt like Moses gazing down from Nebo.

I took the clanking chain ferry from the Studland Peninsula to Sandbanks, a voyage of a few hundred metres that links two different worlds. This is the fourth-most expensive real estate in the world, where women thick of lip and thin of waist, parade around in huge sunglasses walking ugly little dogs, and teak-hued men emerge from Bond-villain houses in the sort of blingtastic cars that make me want to simultaneously laugh and cry.

For the price of a night in a campsite, I bought a coffee and sat at an outside table. People walked past looking at my loaded bike and I prepared myself for the usual questions. "Come far?" "How heavy's all that gear?" But nobody said anything; they just looked at me as if I were some sad freak, and I couldn't help wondering whether money sucks all the romance out of your soul.

I took the little passenger ferry at Hengistbury Head, then the one across Southampton Water from Hythe (that's about a dozen ferries since Land's End), and then the one from Gosport to Portsmouth, a city I've long loved, its littoral landscape – Martello towers, ramparts, and the rigging of HMS Victory and Warrior – now embellished by the sinuous beauty of the 170m Spinnaker Tower.

"Address?" asked the triage nurse at Portsmouth's St Mary's hospital.

"I'm travelling around. Camping mostly," I said. No fixed abode, he wrote in the box. I quite liked that.

I explained that I probably had a stress fracture in my toe, seeing as how I'd just ridden 4,000 miles. I was about to regale him with my story but he'd moved on to the next man, a semi-professional wrestler who'd hurt his arm in a fall. He started to explain the manoeuvre he'd been attempting, but the nurse had moved on to two sheepish-looking teenage girls who'd been tightly holding hands ever since they walked in.

"No need to be nervous," the nurse said.

"We ain't nervous," said one girl. "We're superglued together."

The doctor tweaked and pulled my swollen toe and sent me for an X-ray. "Probably a stress fracture," I said, with some authority, as she looked at the plates. "You see, I've cycled all the…"

"Gout," she said.

"Gout?" I said. "Are you sure?"

"Quite sure."

"That's not, well, very heroic is it?"

"Sorry," she said.