Bunny hop (cycling)

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Bunnyhopping onto a park bench

In cycling, particularly BMX and mountain biking, the bunny hop is a bike trick where the rider lifts the bike over an obstacle while remaining on the bike and in motion. The world record stands at around 4ft or 1.2 meters.

A bunny hop is carried out by approaching an obstacle at speed, lifting the front of the bike and leveling the pedals. If the bike has suspension (full or just front), then the shocks may be "pre-loaded" by applying downwards pressure to them just before the obstacle.

Once body weight has been shifted over the front wheel, the rider lifts the front wheel by pulling up on the handlebar. Simultaneously the rider points his toes to the ground and stiffens the whole body, pushing back on the pedals to keep traction between feet and pedal. Then, a fraction of a second after the front wheel has started to leave the ground, the rider pulls up on the back wheel by bending his knees, still pushing back on the pedals with toes pointed to the ground.

When the back wheel is lifted, the front wheel will lose most of its height, and so to gain any height with the whole bike, the rider must lift the front wheel quite hard. Toe straps or clipless pedals help by allowing more transfer of force between foot and pedal. Using toe straps or clipless pedals is easier at first, but may lead to improper technique as there is less need to point the toes down and push back on the pedals with the body. Pushing down on the handlebars will help the front wheel to land first, if that is desired. Absorb the impact with the arms and legs.

It is a common misconception that a bunny hop without toe clips is achieved by rotating forward on the handlebars. If the front of a mountain bike is lifted up while standing next to it, it is quite difficult to hold onto the handle bars hard enough to withstand the moment of the bike trying to rotate backwards to keep the back wheel on the ground. Since the radius of the handlebars is only about 0.5 inches, even if the center of mass of the bike was only 12 inches behind the bars and the bike only weighed 20 pounds, 20*12/0.5 = 480 pounds of force would have to be applied tangent to the surface of the handlebars to hold the rear of the bike in the air, assuming it was in the air in the first place!

The hop is actually achieved by giving the rider slightly more forward inertia than the bike before leaving the ground. Once the rider and the front of the bike are up in the air, the handlebars can be accelerated forward as well as up. In this way, the moment of the bike causing it to tend to rotate backwards can be counteracted and put it into equilibrium while in mid air.

[edit] Learning to bunny hop

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1) Practice getting your front wheel into the air. Stand up with the pedals parallel to the ground and your weight centered towards the front of the bike. Bend your knees then straighten them - the same way you would if you were jumping without a bike. As your body rises, pull the handle bars up with you. Make sure you are using your whole body to bring up the front wheel, not jerking it with just your arms.

2) Practice getting your back wheel into the air. As in step 1, your weight should be centered towards the front of the bike. You should be standing with the crank arms parallel to the ground, but you should be crouched as if you were about to start sprinting. The back foot should be pushing back on the pedal and the front foot should be pushing forward and down. This position will allow you to use your legs to pull the bike up as your body moves up. Straighten your legs quickly as if you were jumping then immediately pull them up towards your body, keeping your grip on the pedals with your feet. As you jump, your weight should move a little more to the front and your hands should stay in the same position, keeping the front wheel on the ground.

3) Get comfortable. Practice step 1 and step 2 until you start feeling comfortable. Practice raising the front wheel and using the momentum as it returns to the ground to raise the back wheel immediately afterwards. Notice that when you do this, the bike seems to pivot around a point below.

4) Bunny hop. Position your legs as if you were about to raise the back wheel. Raise the front wheel. As soon as the front wheel is in the air, move your body forward and pull up with your legs to raise the back wheel. Try to replicate the pivot feeling from step 3 without letting the front wheel hit the ground first.