Himalayan riding technique: water crossings, loose descents, and an engine with half its power

Why the same stream is a different crossing at three in the afternoon

Most of the water across a Himalayan road is melt, and melt runs on the sun. On the Batal side of Kunzum La, researchers from Jawaharlal Nehru University measured the stream below Chhota Shigri glacier over three Septembers. Discharge peaked at about 2 pm on sunny days, drifted towards 5 pm on cloudy days, and was lowest at about 6 am. They called that stream representative of the melt water streams of Lahaul and Spiti.

It holds under a clear sky. The Jahlma nallah in Lahaul floods in the afternoon without rain, snowfall or even cloud cover, The Wire reported in September 2026. On the Nubra to Pangong road, the Border Roads Organisation's account of a July 2025 rescue records four nallah crossings with regular high discharge and a tourist vehicle stuck in one at about 1600 hrs. When the Kunzum road opened for 2023, the Lahaul and Spiti Deputy Commissioner let traffic through from 8 am to 2 pm. Same clock.

Water crossing technique on a Himalayan road

Walk it first. ADV Pulse's water-crossing guide says to use a long stick or wade in to find the depth before you ride it. You cannot see the hole from the saddle. Pick the line and the exit on foot; the exit is where your eyes stay once you are rolling. Then first gear and a committed throttle: approach at a pace that keeps forward momentum, in ADV Pulse's words, and once you are in, as a 2010 Motorcyclist piece puts it, use enough throttle to keep that momentum and do not close it. No stopping or shifting in the middle. Stand on the pegs if the water looks shallow; between ankle and airbox deep, Motorcyclist's advice is to consider sitting, so a foot is ready to dab. And thumb on the kill switch: if the bike goes over, the engine stops before the intake goes under.

Where your air intake sits, and what happens if the water reaches it

The number you want is wading depth, and no maker of the common tour bikes publishes one. The Himalayan 450 owner's manual says the air filter is located underneath the fuel tank, and Royal Enfield's product page says the intake was put high under the tank so the bike keeps running when rivers are high. No depth. The BMW F 850 GS Adventure manual has you remove the tank cover to reach the air filter. No depth there either. So: intake at tank height, and your bow wave gets there before the still water does.

If water gets past the filter into a cylinder, the piston cannot compress it. The engine stops dead and a bent connecting rod is the usual bill. That is hydrolock. Polaris prints the recovery clearly: do not start the engine. Get to dry ground, dry the airbox, remove the spark plug, turn the engine over on the starter to push the water out, dry or replace the plug, change the fluids promptly. Thumb the starter on a drowned engine and you have turned a wet airbox into a rebuild.

On the far bank your brakes are wet. The UK Highway Code's rule 121 says to test them at the first safe opportunity and, if they are weak, apply light pressure while riding slowly to dry them. The Himalayan 411 manual says the same: ride slowly, applying both brakes intermittently. Before the next bend, not in it.

Going down loose gravel: the rear wheel is the one that lets go

Every descent takes weight off the rear wheel. Under braking, load transfers from the rear axle to the front, and the braking force a wheel can give rises and falls with the load on it, as a Vienna University of Technology study put it in 2001. Point the bike downhill and gravity adds to that transfer before you touch a lever. On loose gravel the rear tyre, now light, is the one that locks and walks sideways.

The Motorcycle Safety Foundation's off-highway guide gives the sequence: both feet on the footrests, point the bike directly downhill, weight to the rear, low gear, throttle closed, brakes applied gradually, in a gear that uses the engine's compression. New Zealand's Ride Forever programme adds the loose-surface bias: in deep gravel, use the rear brake more than the front, and if it gets really deep stand on the footrests to take weight off the front. Both brakes or mostly rear is a real disagreement between those sources. Gradual, low gear, weight back and eyes up are not.

Then the switch on your bike. KTM's description of its Offroad ABS is that ABS is deactivated on the rear wheel, allowing it to lock up, while the front is allowed some slip first. The Himalayan 450 manual lists a Rear ABS OFF setting and only lets you select it at a standstill. KTM adds that the mode demands a significantly higher skill level to maintain control. A locked rear on a straight loose descent is a tool. With the bars turned and a drop on the left it is a different afternoon. If you have never practised with rear ABS off, a Himalayan road is not the place to start.

The engine you ride at 5,000 m is not the one you bought

Air pressure at Leh, 3,500 m, is about 65 per cent of sea level by the standard atmosphere model NASA publishes. At 5,000 m it is about 53 per cent. The power goes with the air, and here the sources stop agreeing. Honda's owner's manuals say horsepower drops about 3.5 per cent for each 300 m of altitude even after rejetting, which puts Leh at about 59 per cent of rated power and 5,000 m at 42. The ISO 1585 standard, as worked through in a 2019 paper from Transilvania University of Brasov, gives a gentler 15 to 18 per cent loss at 3,000 m, and that standard is only admitted down to 0.8 bar, which you pass below 2,000 m. Call it a quarter to two fifths gone by Leh and roughly half on the high passes, and distrust anyone who gives you one tidy number. Fuel injection does not get it back. It keeps the mixture right, which KTM says has made rejetting a thing of the past; a carburetted bike simply runs too rich up here. Either way, the air that is not there is not there.

In the saddle: the gear you climbed a hairpin in at Manali is one gear too high at Taglang La, so shift down before the bend, not in it. Momentum is the thing you cannot buy back, which is why the crossing got a committed throttle. A loaded bike with a pillion feels it first, because the weight did not drop by half when the power did.

How we run it

On our Spiti route the Sach Pass crossing is done early in the day, when the melt streams are lowest, with the support vehicle in company, and our Spiti route page says the same for Gramphu to Batal: before midday. Whoever you ride with, including us, ask when the wheels roll on crossing days and what happens if a stream is up. Waiting for the morning is a plan. Pushing through at four is a hope.