Disaster written all over it ...

This guy has to be our guide. He's all kitted out in the latest protective gear: padded long sleeves and trousers, proper shoes, a helmet that wraps around his serious face. He's the real deal.

The other two guys and I are not as appropriately attired. I'm in shorts and a T-shirt, but at least I've got a small helmet. Matt, having failed to find a stackhat that fits him, has opted to go bareheaded. He signals to one of the guys in the bike-hire shop in Salento, asking if he'll be all right. The guy just shrugs: "Si". This has disaster written all over it.

We're not entirely sure that the guy in the fancy riding gear really is our guide.

No one has introduced him to us and he has remained stoically silent, beaten by the language barrier, but he looks as though he's the only one here who knows what he's doing, so we're thinking: guide.

This is an adventure in the middle of another adventure. We're in Colombia, a country that lends itself to hits of adrenalin by mere dint of being there. The twisting mountain roads have been an adventure. The sight of army personnel clutching machineguns by the side of those roads has been an adventure. And now, riding a mountain bike down into the Cocora Valley promises to be a serious adventure.

We're told to pile our bikes into the back of a truck and climb in alongside for the journey up to the top of the mountain. Our serious guide doesn't bother. He knots a rope to the back of the truck, then secures it to his bike and spends the half-hour journey up the winding dirt road being towed along behind us.

The track we're tackling is not supposed to be a difficult one. Juan Diego, a Colombian we've been travelling with, assured us down below that it was "perfect for beginners". Mind you, this is the same Juan Diego who told us that the machinegun-toting army guys were there to reassure us that "everything is OK", so you have to take that with a grain of salt.

I'm not too concerned. I've ridden a mountain bike before, and I'm sure I can remember how to do it again. It is, after all, like riding a bike.

We get to the top of the trail, on a heavily wooded mountain shrouded in mist. It's beautiful - no one tells you about the beauty of Colombia. They tell you about the guns, and maybe the drugs, but they never tell you about the beauty. However, like fairgoers taking in the sights from the top of a roller-coaster, we've soon got other things to think about.

Our guide signals to us, pointing downhill. Thanks, Captain Obvious. Then he turns and speeds away down a narrow track that's criss-crossed by thick tree roots and covered in a fine layer of fallen leaves. The three of us look at each other, shrug and then take off after him.

There are a few assumptions you make when you embark on organised activity, and one of them is that it must be relatively safe. They're letting tourists do this? Well, it must be fine. It'll be regulated. There'll be safety procedures in place. We'll be OK.

Of course, the world doesn't work like that. Most countries operate on an "if you think it's safe, go ahead and do it" system. There are no regulations here, and no rules. We didn't sign a waiver. There's no safety team following us.

It's about five minutes later, when we catch a last flash of blue shirt between trees as our guide disappears down the mountain ahead of us, never to be seen again, that we figure we might have bitten off more than we can chew.

This track is tricky. Steep, slippery, riddled with rocks and tree roots, the path cut above dangerous drops. Maybe Colombian beginners are more talented than Australian beginners, but this doesn't look like a good place for a novice to be.

Matt is the first to fall. His front tyre rams into a tree root and he's pitched over the handlebars. He grins gingerly, dusts himself off, and remounts.

Gav is next, his bike sliding out from under him on a section of flat rock.

We stop for a break as he recovers, taking in the silence of the Colombian mountains, staring over the rolling green slopes cloaked in cloud. A bird sails high overhead. We joke about where our guide would be by now. At the pub, is our consensus.

Just near the end of the trail we find a long, steep section of mud-covered rock. I decide to dismount and walk it, thinking it will be safer. One step and I'm on my back, clinging to the handlebars as the bike and I slide ignominiously down the mountain.

The three of us finally make it to the bottom, covered in mud, scrapes and bruises, laughing about our lucky escapes. Our guide? We never see or hear from him again. Maybe he wasn't there to help us after all.

Have you ever taken part in an activity while travelling that turned out to be not as safe as you were expecting? Post a comment below and share your stories.