does the bike have a problem if the rear wheel keeps clicking

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Anyone who has ridden a bicycle knows that regardless of the grade or price, the vast majority of bicycles make a continuous 'click-click-click...' sound from the rear wheel if you stop pedaling while riding. Why is that?


The secret lies in the bicycle's freewheel (or rear hub, i.e., the cassette).


Early bicycles had a 'fixed gear' structure, meaning the rear freewheel was just a gear fixed to the rear axle. Whether you pedaled or not, as long as the rear wheel was moving, the chainring would also turn, making it impossible to stop pedaling while in motion.


With technological advancements, the vast majority of modern bicycles use a 'freewheel (or freehub)' structure. This structure, through internal mechanical devices, allows the chainring to remain stationary when not pedaling, greatly enhancing the safety and comfort of the bicycle.


So, why does the freewheel (or cassette) make a continuous 'click-click' sound when we stop pedaling? Please see the animation below:


Internal structure and working principle of the bicycle freewheel


The internal structure of a bicycle freewheel mainly consists of the outer ring's ratchet teeth (the blue part in the animation) and the spring-loaded pawls (the red parts). When we stop pedaling, the rear wheel continues to roll forward due to inertia, driving the rear hub's axle and the yellow part of the freewheel in the animation to rotate. At this time, the ratchet teeth on the outer ring press down the pawls one by one, preventing them from engaging and allowing forward rotation, creating a 'freewheeling' state.


The 'click-click' sound comes from the pawls inside the freewheel being pressed down and then springing back up, striking the next ratchet tooth on the outer ring. A freewheel can have several evenly distributed pawls.


Note: The animation shows the outer ring (blue part) rotating for clarity, but in actual non-pedaling riding, the yellow part rotates while the blue part remains stationary.


Internal structure and working principle of the geared bicycle hub


The working principle of the geared bicycle hub when not pedaling is the same.


When we pedal, the outer ring of the freewheel (or cassette) rotates in the opposite direction shown in the animation. The ends of the pawls firmly engage the less sharp part of the ratchet teeth, stopping the 'freewheeling' state and driving the entire hub to rotate, thus providing power.


Manufacturers typically design 3-4 evenly distributed pawls in a freewheel (or cassette) to ensure a more secure engagement with the ratchet teeth when pedaling.


Internal structure of the cassette




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Created: 2017-09-27 09:49:40