Lugging the Engine

Lugging the engine means asking it to pull hard at very low rpm, usually because the rider is in too high a gear for the road speed or gradient. The engine shudders, the chain snatches and acceleration is weak.

Occasional lugging is not dramatic, but doing it often puts heavy loads on bearings, crankshaft, clutch and chain and can promote knock and carbon build-up. Big singles and twins tolerate low revs better than high-revving fours, but all engines have a minimum comfortable speed.

Change down a gear when the engine starts to vibrate or hesitate under throttle, particularly on hills or with a passenger. On the other hand, lugging is useful off-road on slippery climbs, where low revs help traction, as long as the engine is not struggling.