The Vicious Valley trail starts with a terrifying half-metre drop off a wooden boardwalk. Like all the advanced runs at BikePark Wales in the Brecon Beacons national park, it begins with a qualifier, that is a tricky opening feature where you can check whether you’re good enough for the trail and, if not, bail out in favour of an easier alternative.

At the urging of my sons, who are nine and 11, Harry Lewis, one of our two guides, executes a perfect demonstration of how to ride the drop. Namely by jumping off as high as he can. The kids whoop; my husband raises an eyebrow. Then to our great relief, Harry leads us to the new Kermit trail, designed to provide an altogether less intimidating introduction to downhill mountain biking (though at 5km it’s the UK’s longest beginner trail).

We’re all regular cyclists but inexperienced mountain bikers, so we’ve come to hone our downhill riding at what is widely considered the best purpose-built mountain bike park in the UK. Visitors can ride downhill without lessons but they’re recommended, especially for children. We opt for the Ticket to Ride package, a four-hour taster, which includes basic bike handling and safety skills and as many guided runs on the green Kermit trail as we can fit in. Harry, who works here part-time while doing his A-levels, goes first while our other guide, Colin Dobson, who’s recently retired to do this, brings up the rear. As you might expect, everyone who works here is very enthusiastic about mountain biking.

BikePark Wales opened in 2013, as part of the region’s shift away from coal mining towards adventure sports and tourism. It was set up in a densely forested valley by two pro mountain bikers and experienced trail builders, Rowan Sorrell and Martin Astley, inspired by French ski resorts where you put your bike on a chair lift and ride back down on dirt trails through the woods. At 485 hectares (1,200 acres) it’s the biggest mountain bike park in the UK with an uplift service.

The ski resort template is evident, from the quirky trail names (50 Shades of Black, Pork Belly and Root manoeuvres) to the trail map, which looks just like a piste map, with colour grades indicating the difficulty level, from green to pro-level purple. The 45 runs are also divided into flow and tech trails: the former tend to be smoother, while the latter have more rocks and roots. And within each colour they rank the trails for difficulty, so after you’ve mastered greens you can take on the easiest blues rather than the hardest, which seems like a great idea and something ski resorts would do well to take on board.

Instead of chair lifts, the uplift at BikePark Wales is provided by a fleet of buses pulling trailers full of bikes; it takes about 15 minutes, or four AC/DC songs blasting out of the speakers, to reach the top, at 491 metres. The vehicles aren’t electric yet, but I’m assured that’s the goal, and in the meantime the park offsets its CO2 emissions and uses a 100% green energy supplier. There are also some uphill trails you can climb for extra exercise, though unsurprisingly my kids just wanted to do the downhill.

Until now, our only experience of green, family-oriented trails has been the kind of flat, sedate loops around lakes we’ve all long since tired of, and one downhill run in France that felt far too white-knuckle on account of the constantly moving loose rocks. But the Kermit hits the right note.

We start off slowly, practising tips Colin and Harry have suggested, such as standing up so the bike rolls freely, braking gently so as not to skid, and looking up to read the trail ahead so we have more time to react to whatever is coming. We take regular pauses in the designated rest spots to the sides of the trail to discuss our progress.

Snaking through the forest, over humps and around berms (banked corners), the trail is smooth and it’s easy to lose yourself in the flow. It doesn’t take long for the kids’ confidence to rise – or my husband’s, for that matter: at one point he nearly overshoots the trail into some trees, much to everyone’s amusement. We find that if we leave enough space to the rider in front, we can get up to a good pace on the dips, but those sections are mixed in with flatter stretches, which help us control our speed and stay on track.

There are occasional glimpses of expert riders whizzing above through the trees on different trails and of course on the bus ride, but mostly we felt in our own little world, which I’m sure helped with the kids’ ease of progression.

We manage three very enjoyable runs down before lunch, where we leave our guides for the day. The cafe has exactly what you need to refuel: pumping drum’n’bass and tasty, high-carb fare, from jacket potatoes and pasties to meat and vegan burgers or chilli and rice, with flapjacks and cakes for after.

The kids enjoy a few laps on the pump track, then we head back up to the top to try our first blue, Melted Welly, at Colin’s recommendation. Colin says most groups are ready for a blue after the taster session. It has a similar feel to the Kermit but is slightly faster and steeper. The boys both love it, especially the tunnel section towards the end, but I think they’d have struggled if it was their first run of the day, and by the end I can see the younger one is flagging. Despite his protests, we call it a day.

At his insistence, we’re back first thing the next morning. We may all be far from ready for Vicious Valley, but we’re keen to ride the blues and immerse ourselves in these fast-and-flowing forest trails once again.

The Ticket to Ride package was provided by BikePark Wales. A family ticket costs £280 including bike and protective equipment hire, uplift tickets and four hours’ guided instruction. BikePark Wales is open all year around five days a week (closed Tue/Wed) and seven days a week in the school holidays