We embark on our longest distance of cycling in many years, buoyed by the tailwind and a little wary of some bad weather forecast soon. We want to get to a decent-sized town for a rest day and to contemplate how far we’ll go in Vietnam. We manage it well, and are impressed with the speed we can do it in, although we are harried at the end by the threat of rain. The last few kilometres are the only tough ones, partly from the beginning of some chafing, but mainly because I’m perilously hungry. Every single day of cycling so far, a banh mi stall has appeared as I start to fade, but no such luck today. I screech to a halt on seeing a bakery, and buy an approximation of pizza – without snot cheese – and stuff that down. Later we sit outside a little traditional restaurant and order a platter of do-it-yourself rice paper wraps and fillings; toasting a big achievement and planning future ones.

We are trapped for the next few days by rain, which comes in biblical downpours that don’t let up. Though it gives my saddle sore a chance to heal, it starts to send us insane with cabin fever.

There’s a party for turning on the Christmas lights (which are already on) and we’re asked several times at the hotel about attending, so we really have no choice, and it’s not as though we can sneak around incognito. There’s a lot of kids to giggle at us, which is fine. But the MC wants to interview us, which is excruciating.

Once a few days have passed, we cannot stand being trapped any longer, so on the first day of only light rain we make a break for it. The roads are muddy and the roads are wet, and the endless lorries spray it all over us as they pass, but it’s still better than staying any longer. It’s another big distance day. This time we are stretching ourselves to make up ground, and because we know there aren’t many dry days ahead any more. There’s an unexpected tunnel which cuts out a bit of the climbing we expected, and gets us out of a downpour for a bit, but in all it’s a miserable day, which turns into many miserable days.

We are bombarded with rain. It just doesn’t stop. The roads are full of lorries, and we are perpetually sprayed with mud. There is severe flooding in the south of Vietnam, and we are trapped in the centre.

For a while we are still really enjoying Vietnam, there is a lot to love and the rain cannot dampen that completely. But every side trip we plan, every detour to go off into the mountains or to see some historic sight, is thwarted or made shit by heavy rain or flooding, and we do eventually get hacked off with it.

We set off to do a massive distance to Hue, a place with enough to see that even if we’re stuck again it should keep us busy. For the first two big showers of the day we’re able to take shelter in an abandoned building, and then under a shop awning, but eventually our luck runs out. For the last few kilometres the rain is so heavy and so sudden that the roads flood as we’re riding on them, we can barely see in front of us, and I can feel the rear of my bike aquaplaning. We wade through some deep puddles to get to a sheltered bus stop to wait the worst of it out, but it isn’t going to stop and in the end we just have to carry on.

We’re staying at a not so great hotel in Hue, but it does have a breakfast buffet and it does have a coffee machine. Vietnamese coffee is wonderful, but at breakfast it’s usually in a jug pre-mixed with condensed milk, and kind of lukewarm. Something about hotel buffets attracts the kind of people who stop and hover at the top of escalators, and they gather around the coffee machine and act as if it’s their first day on earth.

On the first dry morning for ages, after managing to not murder anyone at breakfast, we have a dilemma. We should really make the most of it by getting on the road, but we haven’t seen anything of Vietnam since Ninh Binh, so we decide instead to stay in Hue and do some sightseeing. We take a walk to the Imperial city and citadel. There are a million trip hazards among the badly maintained tiles and stairs, but we survive to see it start raining again.

We were screaming along for the start of riding in Vietnam, but now we’ve been bogged down so much that time has slipped away. We always had flights booked out of Da Nang to Bangkok, although we only chose them because they were cheap and we needed to show an exit flight at immigration. But we decide now that we’ll spend Christmas in Da Nang and then make use of the flights. It’s not just because of time. My rear tyre has become worn almost to the point of being unsafe. I noticed it in Taiwan, but against my better judgement I listened to a mechanic who told me it wasn’t bad. Now we’re in a country where we can’t find a replacement with our non-standard sized wheels, and no one will ship here. But we’ve found someone in Bangkok who’ll accept a shipment and hold it for us. It gives me a chance to order a replacement front hub as well, another part that’s hard to find for our vintage bikes.

Back on the road, and heading to Da Nang for Christmas, it just keeps on raining, like the Greg Lake song.

A familiar downpour starts halfway up a steep climb. A woman lets us take shelter in the porch of her house, even making sure we have somewhere to sit. The next one is just after the downhill, where we find the awning of a closed shop. And on and on all day. There are two tunnels today which I’m not sure we can go through. The alternative though is climbing and descending in the rain, and I’m not up for it with the state of my tyre on the wet roads. At the first one there’s a sign very explicitly banning bikes. There’s a guard in a little hut who steps out to turn us away. But we spot a raised service road through the tunnel and mime asking if we can just walk on that with the bikes. He even helps lift them onto it.

As it gets late, we approach the second tunnel and it has the same sign, a similar service road, but a different guard. He won’t let us through. A couple of people come over to film both Richard and him getting tetchy, and he’s clearly not going to budge once that happens.

As we turn back to take the road up and over, I do wonder if he’s done us a favour. We’ve been motoring along on the flat, really able to put the hammer down when we’ve had the chance. Our endurance is really good, but we haven’t done much climbing in Vietnam and the next day’s ride will be over a big and famous pass. We scoot up the climb, and it’s nice to actually be on a road in peace. The honking in Vietnam is batshit insane and it never stops. I’ve almost been sent to the shadow realm multiple times by a coach letting off an ear splitting horn right on my shoulder. In the end we’re both happy we did it, as it gives us confidence for the following day.

We arrive at our destination pretty late. Compared to the last dry day we had of riding, we have done 30 km less and arrived 2 hours later. We contemplated riding to Da Nang in one hit, but we’d have been in a pickle had we tried it.

The next day is what I expect to be the highlight of cycling the Vietnam coast: Hai Van pass. It was featured on a Top Gear special many moons ago, with Clarkson describing it as one of the best coast roads in the world. It’s dry setting off, which is all we ask for. It’s very, very humid, but you can’t have everything. For the most part it’s not too bad. There are quite a few 8% gradient sections, and for me that’s the tipping point between sustainable pain and having to stop every so often. The humidity is really draining. Halfway up we stop beside a small stream and I start to walk over to splash my face, until remembering that an utterly extraordinary number of men in Vietnam use the side of the road as a toilet.

There’s a tunnel alternative cutting through the mountain, and we assume that all traffic except mopeds and tour buses will go through that. But of course there are a fair number of heavy vehicles too. On a hairpin bend a huge tanker in front of me is struggling. I’m behind to the right, in the wide shoulder where I should be, but behind me a dickhead driving a coach is tailgating me and hammering away on his horn to get me to move so he can undertake the tanker on the bend.

The final part of the climb is through heavy mist, which shouldn’t come as a surprise because it’s what the name of the pass means, but it’s quite shockingly thick. We can’t make out vehicles coming the other way even with their lights on, and when I get to the top (first, that is, before him) Richard can’t see where I’ve stopped to wait until he’s almost passed me. It’s a shame because there are no views whatsoever, and it’s a lot of work to not see anything. The descent is blissfully cold at first, and the shrouding mist makes it eerie.

As we get a bit further down, the mist lifts a bit until it’s only light smoke wafting across the road, and we can make out some of the views. They’re a bit crap anyway. It’s not a road or a view that you’d write home about. Partly that is because half of the mountainside is being removed as part of Vietnam’s relentless concrete development. I’m sure it was more beautiful on Top Gear, before this happened, and on a clearer day.

Da Nang is a bastard to get through, but it’s our final destination in Vietnam. We divert to a bike shop on the off chance they have anything we need, and because both our bottom brackets have a bit of play in them. The owner/mechanic services mine, but warns it doesn’t have long left. He advises keeping the one I have now, because it’s still better than what he can offer. Another part that is going to be hard to replace. Richard’s on the other hand is completely dead. It was a cheap fix in Laos a couple of years ago, so it hasn’t done too badly. He is able to fit something a bit better now. It was always a gamble to set off with these bikes with their original specs, but the alternative would have been a complete and costly overhaul. We may not have made the right decision.

It will now be Bangkok for a few days while we give the bikes some attention and bulk up on 7 Eleven toasties.

After that, South East Asia is over and done with, and it’s on to the next chapter. I’m glad we came back to Vietnam, but am also looking forward to leaving.

A playlist for the ride: