Bicycle Parts: Chains, Gears & Ball Bearings : Ball Bearings & Their Function on a Bicycle
Charles McMahon for Expert Village. We are
talking about the bicycle. You can get more in-depth information by looking at my college
level textbook and you can see that on merionmedia.com. In this segment, we are going to talk about
wear resistant materials and specifically bearings, ball bearings. Now, here is where
you are going to find ball bearings, on each side of the hub, there is a set of bearings.
There are two sets of bearings here in the head tube. There are bearings in the pedals.
There are also bearings back here in the rear hubs on each side. Now ball bearings, as you
probably know are to give you very small rolling resistance to any time you have motors and
anything where you get things spinning around we normally use ball bearings and the ball
bearings are little balls in the seat often you have grease in there to give you extra
lubrication and the bearings are hardened steel, in other words you take alloy steel
raise it to a high temperature, you clench it and you temper it a little bit and you
have a very hard steel and the principle in wear resistance is that you want hard materials
on other hard materials, in other words they can’t squash each other because you have
two metals together and you press them hard together and they start squashing, you can
get what is called cold welding in little spots and then it can be ripped as you are
spinning the thing, you can be ripping off little pieces from one side or the other that
is how bearings or any other moving pair of metal parts fail, so you want hardened steel
bearings. Now ultimately if you want the greatest kind of bearings, you use ceramic bearings
because they are lighter than steel bearings and they have even much greater wear resistance,
so the new thing in bearing is bearings made out of ceramics, particularly a ceramic called
silicon nitrite, but in most cases the bikes are just made with hardened steel bearings
as are the bearings in cars and other things.