Chain snaps on a fast secondary road
You are riding a 900 cc adventure bike at 90 km/h on a two-lane secondary road with a 90 km/h limit. There is a hard shoulder 1.5 m wide on the right and a crash barrier beyond it. Without warning you hear a sharp crack and the rear wheel locks briefly, then the engine races as the bike loses drive. You are in the right lane, 200 m before a slight left bend, with a lorry 60 m behind you. Your pillion passenger is on board. You have a first-aid kit, a warning triangle and a hi-vis vest under the seat.
1. Describe your immediate control inputs and where you bring the bike to a stop.
Read the worked answer
Keep the bars straight and avoid grabbing the brakes. The rear wheel may have locked when the chain failed; a locked rear can step out. Ease off the throttle, let the engine settle, and use gentle, progressive braking, mainly with the front, while keeping the bike upright. Do not swerve.
Signal early and move to the hard shoulder, but check the mirror and blind spot first: the lorry is 60 m back and closing. Aim to stop as far right as possible, parallel to the barrier, leaving room for the lorry to pass. If the shoulder is too narrow or blocked, stop on the verge only if it is firm and safe. Avoid stopping just before or in the bend where sight lines are short; if you can, roll past the bend entry to a straighter, more visible spot, but only if the bike remains controllable.
2. Once stopped, what is the order of actions for you and your pillion?
Read the worked answer
- Switch off the engine and put the bike on the side stand. 2. Get the pillion off on the traffic side away from the road, i.e. toward the barrier or verge, never into the traffic lane. 3. Both of you put on hi-vis vests. 4. Put out the warning triangle if it is safe and legal to do so, placing it far enough back to give approaching drivers time to react, but never walk into a live lane. 5. Keep behind the barrier if there is one. 6. Call for assistance.
Do not attempt a roadside chain repair in a live lane. If the bike can be pushed clear, do so; otherwise leave it and stay safe.
3. What would you inspect before deciding the bike can be ridden again, and what is the likely cause?
Read the worked answer
A snapped chain usually means the chain was worn, poorly lubricated, badly tensioned, or had a damaged link. Inspect the chain for stretch, kinks, missing O-rings and damaged rollers, and check both sprockets for hooked or worn teeth. Also check the chain guard, the swingarm and the crankcase for damage from the whipping chain, and check the rear wheel and brake line.
A new chain on worn sprockets wears out quickly, so replace chain and sprockets together if either is worn. If you have a spare link and tools and can do it safely off the carriageway, a temporary repair may get you to a workshop, but only at low speed and short distance. Otherwise recover the bike. Do not ride with a damaged chain guard or a chain of unknown condition.