Cycling the delta: heat first, traffic second

These are long-term averages for Can Tho, the delta's central city. The recorded maximum is 40.0 °C, in April. Relative humidity runs about 78–81% from January to April and 84–87% from May to November, which slows the cooling effect of sweat.

• Start early. On the bikes by 06:00 on most days. The first two hours are the coolest of the day.
• Stop in the middle. Off the bike by 10:30–11:00 and back on after 15:30. The UK health service's general advice is to stay out of the sun between 11:00 and 15:00.
• Drink on a schedule. A water stop every 45–60 minutes, whether you feel thirsty or not, with fruit and salted snacks.
• Know the signs. Heat exhaustion shows as tiredness, dizziness, headache, nausea, heavy sweating, cramps and strong thirst. Cooling and fluids should bring improvement within about 30 minutes. Hot skin that has stopped sweating, confusion or collapse means heatstroke, which is an emergency.
• Use the van. Climbing into the support vehicle for an hour is part of the plan, not a defeat.

On delta roads you share space with motorbikes, and worldwide more than half of all road deaths are pedestrians, cyclists and motorcyclists, according to the World Health Organization. The same fact sheet notes that every 1% rise in average speed raises the risk of a fatal crash by about 4%. On a bicycle, your protection is to be where speeds are low.

That is why our routes use the small lanes. Main roads in the delta are busy; one cycling writer singles out Highway 1A between Ho Chi Minh City and Can Tho as a road to avoid, and route notes describe the last kilometres into Can Tho as heavy traffic. Where a main road is unavoidable, we put the bikes in the van.

• Single file, always. Vietnam's law bans motorcycle riders from riding abreast; we apply the same rule to our bikes because the lanes are narrow.
• Slow over bridges. Many are steep, narrow and without rails.
• Call out mopeds. The guide at the front calls oncoming traffic; the sweep rider at the back calls overtaking traffic.
• No riding after dark. Lanes are poorly lit.
• Helmets on every ride. The law's helmet clause covers motorcycles and mopeds, not pedal bicycles, but we do not ride without them.

Good rental bikes are hard to find in small delta towns, a point Saigoneer made years ago and which still holds. We bring bikes from Ho Chi Minh City in the support vehicle, sized to the heights you give us. Hybrid or flat-bar bikes with wider tyres suit the patched concrete better than road bikes. Some sites rent their own: Tra Su, for example, hires bikes for two hours inside the forest, but they cannot leave the site.

E-bikes are an option where available. Under Vietnamese law an e-bike's motor assistance must cut out at 25 km/h, which is above any speed you will want on these lanes.