Plenty of Vietnam’s side roads are not tarmac: construction detours, village lanes, river-track approaches and mountain access roads all turn to gravel or packed dirt, especially after rain. A semi-automatic underbone handles these surfaces better than its street styling suggests — provided you change how you use the throttle, brakes and gears.
The one-sentence rule
On loose surfaces, the tyre grip you lose is rear grip and front grip in different places: the rear spins and slides under power, the front washes under braking. So: power gently, brake even more gently, and let momentum do the work.
Throttle and gears
- Second gear, not first, on anything looser than hard-packed dirt. First gear’s low ratio turns small throttle openings into rear-wheel spin.
- Constant, small throttle. Acceleration shifts weight rearward and lightens the front — on gravel this happens faster than on tarmac. Roll on and off in slow motion.
- Shift by feel, not speed. If the engine is screaming, the bike is fighting for traction; upshift early. If it is labouring and jerky, the surface is stealing momentum — downshift smoothly.
- When the rear spins, do not snap the throttle closed. Hold it where it is, let the wheel catch up with the road, then ease off gradually. A centrifugal clutch actually helps here — it slips a little and softens the shock.
Braking on gravel
The front brake is your friend on tarmac and your enemy on deep gravel. Use it, but with two-finger caution: gentle, progressive, and earlier than on asphalt. Let the rear brake and engine braking do more of the work. On a downhill gravel stretch, choose a low gear before the descent and let the engine hold the speed with almost no brakes — locking a rear wheel on loose gravel happens easily and the bike steps sideways fast.
Steering and body
Loose surfaces reward a loose grip on the bars. Let the front wiggle — it is doing its job — and steer with weight shifts and your eyes, not muscle. Sit slightly forward to keep the front tyre loaded, and stand on the pegs with knees bent on the roughest sections; your legs become the suspension the bike does not have. Look far ahead and pick your line early: hard-packed wheel tracks usually beat the loose centre.
After the dirt section
Gravel sticks in the chain, brake calipers and every moving part. A quick look at the chain after a long dirt ride is worthwhile — and the chain-maintenance guide explains what to check. Deep-dust days deserve the same care.
You do not need an adventure bike for most Vietnamese dirt roads — a sensible rider on an underbone covers them safely every day. If your routes include unpaved stretches, contact us to confirm current availability of higher-clearance models.