a cross section applies to anything...it is a way of looking at something inside.
imagine cutting through a pump (for example) and then looking perpindicular at it, like holding it out in your hands like binoculars, the shape that you see (a circle probably in this case) is called the cross sestion.
smaller cross-section of tread in contact with road
You can pump it with a bicycle pump with the needle.
Bicycle Moto X, with X meaning Cross.
A Bicycle Pump is used to pump the tyres on Bikes it is normally a simple hand operated device which pushes air through a tube atached to a nozel which is screwed to the Valve on a Bicycle inatube the air is then forced into the Bicycle Tire.
The initials used for Bicycle Moto-Cross are BMX.
Bicycle pumps are most commonly found and sold at a bicycle store. One may also find a bicycle pump at a local retailer such as Walmart or Target, or online at Amazon.
with a bicycle pump
There's no set "recipe" for the sizeof the parts of a bicycle pump, other than that they have to fit together. A floor pump might have a 2" piston while a road bicycle hand pump might be 3/4" or smaller.
A cylinder has a circular cross section that is parallel to its base.
Bicycle Moto Cross
you get to the other side
BMX