Bicycle pump
From Free net encyclopedia
Image:Bike pump.jpg Image:Bicycle Pump foot operated.jpg Image:Bicycle pump frame mounted.jpg A bicycle pump is a type of positive displacement pump specifically designed for inflating bicycle tires. It has one or both of the two types of valve in use on bicycles, Schrader or Presta. Basic types available include:
- floor models or track pumps
- frame mounted
- compact or mini
- double action
In its most basic form, a bicycle pump functions via a hand-operated piston. During the up-stroke, this piston draws air through a one-way valve into the pump from the outside. During the down-stroke, the piston then displaces the air from the pump into the bicycle tire. Higher-end models have a built in pressure gauge to indicate when the tire is optimally filled.
Caution must be used when using a gas station air pump. Some are designed to cut off before the high pressures used in many bicycle tires are reached. Some others may pump enough air into the small volume of a bicycle tire in a short time to blow out the tire. There is also a slight difference between the modern standard for Schrader valves on an automobile and that on a bicycle which makes some more recent valves on gas station pumps a poor fit.