It’s 6.30am and the sun has just risen over the broken teeth mountain tops of the Dolomites. It casts a warm glow over the jagged rock face, as I look back and see 7,000 cyclists charging up behind me.

The gun has just been fired on the Maratona dles Dolomites – one of the most demanding mass-participation races in Europe, which pits riders against the mighty mountain passes of the Alta Badia region of the Italian Alps.

Stretching along 138km of closed roads with a total 4,230m of altitude gain – almost equivalent to reaching the summit of Mont Blanc from sea level – the hardest of the three routes is equivalent to one of the toughest stages of the Giro d’Italia, Italy’s version of the Tour de France.

But the Maratona is not aimed at the elite – in fact, pro-riders can only participate by invitation. Instead, the race is firmly on the bucket list of club riders from across Europe and as far afield as the USA, Brazil and Australia.

On a training ride to test out my legs on one of the gentler hills of the route, Oli Beckingsale, a former pro and three-time Olympian who now runs the Kudo Coach training app, told me: “Every passionate cyclist dreams of riding the routes of the Giro, following their heroes up the mountain passes of the Alps – this is more than sightseeing, this is fantasy coming to life.”

As I start pedalling, awash with trepidation at the thousands of metres of climbing ahead of me, Oli’s advice rings through my head: “Keep it steady, there will be lots of keen riders speeding past, don’t get pulled along in the excitement or you’ll blow up on the later climbs.”

Slow and steady will be my mantra – not that there was ever any risk I would be racing ahead on this route.

The first of the seven mountain passes, the Campolongo, is a gentle introduction to the climbs in store, at just 5.5km long with an average gradient of 6.1%.

As I swing round the bend of the first switchback, I look back over Corvara, the spiritual home of the Maratona, and the immense backdrop of the mountains overlooking the lush green valley takes my breath away – although I need every breath I can get as I begin my climb.

Before the peloton is splintered by the slopes, I spy celebrities from the cycling world ahead of me, from 26-year-old Dutch pro Puck Moonen to Miguel ‘Big Mig’ Indurain. Now I can boast I have ridden the Dolomites with the five-time Tour de France winner.

The excitement of the morning carries me up to the stark, rocky plateau of the pass and straight on to the speedy descent, where more experienced riders whoosh pass me as I take a cautious line down the centre of the road.

I realise what a privilege it is to have closed roads for the event, allowing me to take advantage of the full sweep of the bends without fear of coming face-to-face with a motorcycle or car coming up the other way.

The only vehicles are the support cars, who quickly come to my rescue half-way through when my saddle suddenly slams down. If only a mechanic was on hand whenever I go for a ride at home – the true pro-rider experience.

As soon as I start to gain some confidence on the descent and settle into the pattern of brake, lean, pedal, brake of rolling down the sweeping switchbacks, I arrive at the foot of Passo Pordoi, the first of the major climbs of the day – which at 9.9km long, reaching a height of 2,239m, is the highest point in this year’s Giro.

But it is Passo Giau, the penultimate climb with an average gradient of 9.3% over 9.9km, that challenges me to the core.

As I reach each of the signs counting the 29 switchbacks of this immense climb, I coax myself into making the effort to keep turning the pedals to the next bend. But approaching the halfway point, I see my heart-rate rising over 175 on my bike computer, as sweat runs down my face and I feel my body overheating. I know I have to find some shade to cool down, or there is no way I will make it over the top.

Once off the bike, it takes all my willpower to get back on and face the road again, which I can see crawling round the valley, a steady stream of cyclists pulsing upwards.

Finally, it is the thought of going home empty-handed, without the beautiful finisher’s medal, handcrafted from crushed hay with a real daisy at its centre – part of the Maratona’s bid to be more sustainable using local resources – that propels me to swing my leg over the saddle and begin the grind again, upwards and onwards to the finish.

After all the mountain passes and just 4km from the finish line, the organisers have thrown in one last sadistic hurdle of the Mür dl Giat. The Cat Wall is a 370m hill with a punishing 12.4% gradient – lined with early finishers, beer-in-hand, cajoling and cheering you up the sickening slope.

Every part of my body screams at me to get off and push, but my ego overrules my cramping legs. I lift my bum out of the saddle for one last humongous effort and somehow crawl to the top, my face a mixture of ecstasy and exhaustion. Now all that’s left is to roll over the finish line.

The morning after all this exertion, I had been expecting to be fit for nothing but lounging in the pool at the Greif hotel – a ski hotel which keeps its doors open for summer guests (greif.it/en/). My legs feel surprisingly sprightly, however, and I decide to take advantage of the ski lifts, which also remain open to save the trek above the tree line.

As we are whooshed up in the gondola, I see mountain bikers bombing down one of the many trails cut into the valley below.

While riding the Maratona, I had seen several electric mountain bikes buzzing up to the top of the tracks, and felt envious of their silent motors magicking them uphill at an unnatural pace.

Ahead of me as I step out of the lift is a glorious panorama, a single wispy cloud bouncing off the top of the expanse of mountaintops domineering the valley below.

I spot a group tightening up their bootstraps, their pet spaniel barking excitedly at their heels, ready for a hiking adventure along the mountain paths that link up the same passes I cycled the day before.

But for me, a seat at the stylish Piz Boe’ Alpine Lodge restaurant (boealpinelounge.it/en/) beckons, for a fine dining lunch of seafood spaghetti while absorbing the view of the mountains that punished me so severely just 24 hours earlier.

How to plan your trip

The next annual Maratona dles Dolomite race takes place on July 2, 2023. Visit maratona.itFor more information on the destination, visit altabadia.org