Midnight in London and I'm racing through Shoreditch, heading for the Pub on the Park. It's the night of the Dunwich Dynamo, and once again I'm late. Last year I set off at 10.00 pm after a day at the raspberry harvest, this year the excuse is a wedding in Brighton - and when I pull up outside the pub I find nothing but a handful of tipsy revellers, not a cyclist to be seen. It's clear I'll have my work cut out catching up with my friend Moni's group, who set off hours earlier. I point my bike north, turn on the Garmin and begin the chase.

Now in its 22nd year, the Dunwich Dynamo is a something of a cult phenomenon. An annual 112 mile night ride from Hackney in London through the wilds of Essex to the ancient (and non-existent) city of Dunwich on the Suffolk coast, it has grown from humble beginnings - a small group of cyclist friends in search of high jinx - to become an institution with hundreds, maybe thousands, taking part each year. The beauty of the Dun Run is the relaxed atmosphere. This is not a race or a sportive, it's a free communal ride, and the organisation by Southwark Cyclists is just the right side of minimal. You won't find arrows signing the way at every junction, and there are no medals, certificates or sponsors' goody bags waiting at the end. Just a stony beach, a packed café, and a trail of flickering lights all the way to the North Sea. That is, if you set off on time...

The sun came out soon after this photo but by then my phone battery had died
The sun came out soon after this photo but by then my phone battery had died

After negotiating my way out of the tangle of streets around the pub I was soon on the Lower Clapton Rd rolling north. Hanging a right on the roundabout, the route turned east up Lea Bridge Rd and the A104 making a beeline for Essex along brightly lit streets still busy with nightlife. But in a surprisingly short time London recedes into the distance behind, and suddenly I'm riding through a dark tunnel of trees that is Epping Forest and grateful for my bright front light, which survived a fall onto the road en route here with only a few scratches.

I'm also grateful for the tailwind pushing me up the long drag up to and beyond the Robin Hood roundabout, and hope to myself that it keeps up all the way to the finish. It's a warm, sticky night - no rain yet, but the roads now are wet from a recent shower. I pass a burning car at the roadside and stop while police briefly hold up traffic to allow a fire crew on the scene. The flames are soon doused and I roll on. North through Woodford, Buckhurst Hill, Epping and North Weald Bassett - and now I really am in the countryside, or it feels that way at night. The roads are silent, and I still haven't seen a single other cyclist. On these smooth roads that still carry the painted slogans and messages of support from last week's stage 3 of the Tour de France, I am Lanterne Rouge on the Dunwich Dynamo.

Being last is one thing, but being last and lost is another. Unfortunately my Garmin has taken against the GPX route I downloaded the night before, and every few minutes it bleeps a warning: "Off course". This is not good for morale. I pull over by a roundabout somewhere near Moreton and wait for maps to load on my phone.

It's worth noting that this kind of problem is entirely avoidable. Most people carry maps with them on the Dunwich Dynamo - if you arrive at the Pub on the Park at a decent hour, the organisers issue printed maps and a route guide. I've missed that particular boat, but prodding at my phone I manage to find a website with turn-by-turn course instructions for the route. For the next few hours, I will be relying on a combination of this, the maps app on my phone and my own hazy memories of the previous year's ride to plot my course.

Having to stop every few km to check my bearings proves a hindrance to progress, and in any case I'd have no chance of catching up with my friend Moni's group, who set off a few hours ahead of me.

At 4.24 and with 50 miles done, I get a message from Moni asking how it's going: 'there is a bacon sandwich, coffee etc stand just 17 miles before dunwich as well!'

Ah, bacon... I remember that stand from last year, I think it's in someone's garden along the roadside. I recall pulling over for a chat and cup of tea. But there was little left in the way of food even then, and I know that with 50 miles to go, by the time I get there this time the stand will likely be closed and the proprieter will be fast asleep in bed.

Passing through a town beginning with F - Finchingfield? Fyfield? I almost crash into two geese standing in the middle of the dark road. One honks indignantly as I brake almost to a standstill and steer between them. I pass a pub that I remember being open last year, and full of cyclists making merry - the last pub of the night, followed by a bracing little climb on the hill out of town that I remember as I crank up it alone.

It's dawning on me, as the sky gradually brightens to lighter shades of grey, that riding the Dynamo solo is not the ideal way to approach this event. Last year, again chasing a group of friends with a head start, I was lucky enough to fall in with another lone rider just past Epping whose lovely Mercian bike caught my eye. He was checking his map at the roadside, and it turned out he was one of several Guardian journalists on the ride. We ended up cycling the entire route together, dipping in and out of various groups and pubs along the way, and the conversation helped pass the long miles of flat Suffolk fields.

But here in 2014, it's pushing 5 am, I still haven't seen another cyclist, and it's been raining persistently for the past 2 hours. Wrapped in my lightweight rain jacket I'm soaked to the skin, but it's a mild night/morning and it's only when I stop to take my bearings that the chill begins to bite. My thoughts start turning to the warm bed I left behind. Why am I cycling through the night to a godforsaken beach in the middle of nowhere? Why do we do this to ourselves?

Flora Tearooms  without which none of this could take place
Flora Tearooms without which none of this could take place

At last, on the outskirts of Sudbury, there is a breakthrough. As I'm grinding up the cheerily named Gallows Hill I finally catch sight of some fellow riders - the first I've seen all night. It's a couple of guys, one on a fixie, the other wearing a cap peaked up against the drizzle. We exchange greetings, but have only been riding together for a matter of moments when the fixie announces he has a puncture. "Bound to happen sooner or later" he says with a resigned smile. Up ahead there's a garage forecourt that offers shelter, but across the roundabout I spot something even better - a McDonald's...and it's open.

"I wouldn't usually stoop to this, but..." I tell myself, as I gratefully park up the bike by the window and, cleats clacking, totter inside to join a knot of fellow cyclists and early shift policemen at the counter.

Having only eaten two mandarins in the past 12 hours I'm ready for breakfast and a coffee. I gulp down a steaming Mc-something-or-other with bacon and egg while puddles form around my shoes on the tiled floor. At the next table a group of six riders are debating whether to continue or beat a tactical retreat to Sudbury train station. We're roughly at the halfway point, with at least 50 miles still to go, but it's almost 6.00 am. The rain shows no sign of easing off, so at last I finish my coffee, get up and trudge back out doing my best 'hero face' to encourage the others.

Hero face can only get you so far. I quickly regret leaving the relative comfort of the golden arches; within a minute my teeth are chattering with cold as I rejoin the B1115 heading north east. I note a Folly Road to the right and fail to crack a smile.

Fresh as a daisy. This fly is coming home with me as a souvenir.
Fresh as a daisy. This fly is coming home with me as a souvenir.

It's not long before I catch up with some more stragglers. At first I'm confused - surely I was the last person on the road? But it turns out they've come from the nearby food stop, which I had missed without the map directions. My new companions are well equipped, a young chap and his father who has the route map and notes in a waterproof case mounted on the cockpit of his touring bike. Just the sort of practical types you need at a time like this, and I'm happy to ride along with them for a few miles chatting.

After 20 minutes we spy another knot of pilgrims on the horizon, and soon I'm matching pedal strokes with a young lady whose opening line is deliciously provocative. "How come you're back here then, did you have a puncture or are you just slow?"

I make my excuses, and in turn ask what a nice girl like her is doing in a place like this - surely a series of unfortunate events?

Yes, a few friends have had punctures - in one case a whole tyre has laid down its life for the cause. She sighs, clearly irked at being held up in this way. 'My dad told me I couldn't do this,' she confides, 'so...'

Dad, it turns out, is a keen cyclist who knocks out a century in about 5 hours, and his daughter is hoping to rival that on the Prudential RideLondon-Surrey 100 in August. I wish her well with that. I'm hoping to get around the course in under 24 hours myself.

Somewhere around Needham Market I lose my new companions. It's a confusing part of the route, with bridges and industrial estates jamming my radar. There is a feed stop by Needham Lake that I remember from the previous year, but this time all I can find at the otherwise deserted water's edge is another small group of cyclists looking at maps and road signs for clues. One of them finds a discarded plastic cup and holds it up forlornly: exhibit A.

I heart fish  the Dunwich town motto.
I heart fish the Dunwich town motto.

I break the news; the food stop was here, but must have packed up and moved on some time ago. While they go in search of a Co-op for shelter, I fall in with a recumbent rider and after a couple of wrong turns we set off in what we hope is the right direction. He falls behind instantly, but I can see that the father and son from earlier are close behind so forge on ahead, crossing the A14, heading north up the A140 briefly before turning off onto Needham Road into Coddenham. This part of the route is vaguely familiar to me from last year, but I'm still grateful when, miraculously, two consecutive junctions are marked with signs for the Dynamo - the first I've spotted so far.

At this point I'm meeting the occasional cyclist flitting back towards London on the return journey - some people are that crazy - and just after Coddenham I call out to one such lunatic to ask whether I'm on the right road. It's a lucky encounter, as he directs me up a minor turn-off up Stonewall Hill just metres ahead that I'd certainly have sailed past otherwise. Thanks mystery cyclist!

I trundle up the hill, by now starting to flag a little and fantasising about chocolate. Ninety-something miles done. What I really need is a town with a shop open early on a Sunday...

Across the endless steppes of Suffolk, salvation arrives at last in the shape of Framlingham, arguably the last outpost of civilisation before the sea (no offence to Peasenhall, Yoxford and Westleton). I ride into town like a weary cowboy after weeks on the prairies, and a paperboy points me to a newsagents. I toy with the idea of a tin of cold beans, but my multitool doesn't have a can opener so I settle for a Snickers.

Something about a stranger in cycling kit seems to invite conversation. I've no sooner sat down outside the shop to eat and stretch my legs out than a local chap with a bike approaches. 'Are you on the Dynamo?' he asks. He rode it a couple of years ago himself. He tells me about seeing someone do it on a penny farthing. This is undeniably impressive, but part of me wonders whether it wasn't just another local riding his regular bike. I wouldn't be surprised if there were a few penny farthings knocking about in garden sheds around here. I ask the gent what towns I should aim for next and he tells me to look out for Peasenhall. 'Well, good luck!' he says and wheels his bike up the street.

A respectable looking woman in a cardigan is next. "Ooooh, that's a long way," she tuts when I tell her where I'm going. What time do the coaches leave?' She shakes her head when I tell her. "It takes me at least an hour to get to Dunwich from here in the car," she warns in parting. It's only 9.00 am, I think to myself, plenty of time. At this point on the ride, it's not a question of whether you'll finish - it's just a matter of churning out the last few miles and hoping you get there before the Flora Tearooms café is washed into the sea along with the rest of Dunwich.

There's some people on the beach. They think it's all over
There's some people on the beach. They think it's all over

The rain has stopped and the sun is out as I cycle up the hill past Framlingham castle and north towards Peasenham. The route here follows a zigzag along quiet rural lanes, arcing south through Yoxford, where I possibly miss a turn off, come to think of it, continuing south to Theberton and then north to Westleton rather than straight across. No matter: the end is in sight now, I can almost smell the sea (although it could be my kit) - and finally, after 106 miles, at last there's the first sign for Dunwich.

This tangible proof that it actually exists lends me an extra crumb of energy. I pick up the pace along the final couple of miles, passing the ruined monastery walls on the right and overtaking some fellow riders on the final bend before swooping down the hill and into the car park at the finish. The time is 10:19 on Sunday morning, and I've been on the road for just shy of 10 hours - of which I calculate at least 2 hours were spent trying to shield my phone map from the rain as I worked out which road to take next.

I text Moni to ask if she's still here. 'Already in London' comes the reply, 'heading back to Brighton soon. I am well impressed!'

You're impressed? The girl's just finished her first Dynamo and maiden century - and made it back to London while I'm still swatting flies off my face on the beach! Hats off Moni - and she even managed to completely dodge the rain, a fact about which I am only slightly bitter.

Usually at the end of a sportive there's a few minutes of relaxation, and Dunwich is no different - the done thing is to jump in the sea, or at least stretch out for a nap on the shingle. But first I join the queue of colourful jerseys and weary, exultant faces for coaches back to London, which stretches around the car park and isn't moving very quickly. It takes an hour to get to the end of the queue, during which I hang my sodden printed coach ticket over the frame of my bike to dry and exchange ride notes with those either side of me in the line. As I'm waiting I spot two cyclists I recognise from Sudbury McDonald's - a cheerful young couple - come gliding into the car park all smiles.

Never had helmet chips? You haven't lived
Never had helmet chips? You haven't lived

Formalities over, there's time for chips and a spot of sunbathing on the beach before the coach leaves at midday. I watch my bike being loaded along with 250 others into the back of a truck - a nervous moment for everyone - and then it's onto the coach for the three hour drive to London.

If I hadn't spent the journey fast asleep, I would no doubt have had time on the bus to reflect on some valuable lessons from my experience of this year's Dynamo. Or one lesson at least: leave on time! The Dunwich Dynamo is a fantastic event, but in the dream scenario to which we all aspire, you don't want to be riding half the night on your own and miss all the camaraderie that makes this ride so special. Next year, I solemnly swear, I am leaving the pub at 9.00 pm. Raspberries and weddings permitting, of course.