Bicycle Mechanics - What causes

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View Full Version : What causes


StormRider
06-26-02, 09:27 AM
the clicking sound when I coast?? It is supposed to happend there is no maintenence issue:confused:


WorldIRC
06-26-02, 09:45 AM
u mean when urr not pedalling and the one that comes from urr back wheel. that is urr free hub i think. thats normal. all bikes do it. cuz basically when u dont pedal i think urr wheel spins and urr freehub doesnt. therefore it clicks. when u pedal everything spins tho so no click. dont worry about it

StormRider
06-26-02, 10:28 AM
I know its nothing to worry about, but what is a free hub?
I hate to sound so ignorant


WorldIRC
06-26-02, 10:41 AM
the hub is the metal thing in the centre of urr whel that holds the spokes. the freehub is the outside part of the hub. its what the cassette and freewheels are connected too

MikeR
06-26-02, 11:17 AM
StormRider,
Do you know what a ratchet is? If you have used a socket wrench set, the handle that the sockets attach to is a ratchet. If you take a ratchet wrench and turn it one way it will turn the nut, but if you turn it the other way it will slip and make a clicking sound. This way you can put the ratchet wrench on the nut and just move he handle back and forth. The nut will turn when going one way but the wrench will ‘slip’ when going the other way.

A ratchet is a mechanical setup that enables something to be turned one way but to ‘slip’ when turned the other way. Inside your bike's rear wheal is a ratchet mechanism that allows you to pedal one direction and coast (or slip in the other direction)

A ratchet is made up of a series of little ramps around a wheel. Going one direction the ramps rise gradually up and then abruptly drop straight down. Leaning against the wheel is a pawl held by a spring. Think of a pawl as an arm shaped like a 7. The top left edge of the 7 is riding over the ramps on the wheel. When the wheel is turned in one direction the 7 hits against the steep side of each ramp and this engages it so that it is forced to move with the wheel. Rotate the wheel the other way and the 7 rides up the gradual rise of the ramp and then drops of the edge, then rides up the next gradual rise. This slipping over the ramps and dropping off is what causes the clicking.

It's easy to understand if you see a picture of a ratchet. Hope this helps.

MikeR
06-26-02, 11:39 AM
Here is a crude drawing of a ratchet. If the inner red wheel is turned one way the pawl will ride over the ramps (making a clicking sound). If the red wheel is turned the other way the pawl will catch on the steep side of the ramp and that will force the outer wheel to turn.

MikeR
06-26-02, 12:39 PM
Here's a web site that explains and shows it better.

http://www.enged.com/students/mecsys/mecsys63.html