When practicing wheelies, assume whatever object is, or will be within 500 feet (152.4 m) of your direction of travel, you WILL hit. Remember, you have no steering and no front brakes whatsoever when on one wheel. Even when your front wheel comes down, your shocks are compressed, therefore no brakes until they decompress.(Edit:The position of the suspension has no bearing on the operation of the brakes.) (Edit: The front brake will work just fine with the front suspension compressed. The problem is inertia. If you slam on the front brakes the back will start to come up. This effect is increased with the suspension compressed and you wind up in the "endo" stunt position. If you are meaning to do this and can control it, fine. If not, you just wrecked your bike and possibly injured yourself.) This could take 100 feet (30.5 m) depending on speed! Make sure the path is clear at all times!!