Reid
Well-Known Member
ANY bike can develop a shimmy. I am sharing my limited experience just in case shimmy ever affects your ride.
Good articles here explain viewpoints on cause and cure.
Well, it happened to be that in the past week my CCS had become shimmy-prone.
I could not ride with hands off the bar at 12mph or more without a progressive, nasty shimmy propagating.
Made no difference if I locked out the fork or not.
Nothing had been recently changed. But a shimmy was now my companion on every ride.
The headstock bearing was free and without any perceptable play.
Bear in mind, my short handle bar, my non-stock Michelin Protek Urban tires, and other factors make my bike different than stock...sort of changing its tuning, so to speak, regarding the shimmy that almost any bike can develop given circumstances.
Yet, I rode many, many miles before without any shimmy.
Shimmy is a self-amplifying positive feedback mechanism. It starts small, so small you cannot notice it. It must be damped, I find, before it can grow larger. The expert articles linked above don't make this simple point: damping the shimmy before it can grow out of control may be important to curing your shimmy, if you ever have such trouble.
My own bike's cure was effected by tightening the headset bearing just a bit, putting a bit of preload on it (normally a bad idea). The resultant friction is not enough to make hands-free riding at all difficult. But it has banished the formerly nasty shimmy entirely.
Many years ago I restored and drove a 1922 Model T Ford as my sole car. It had a perfectly fitted front end, no shake or looseness in any of the various joints. It would shimmy the car to a halt once the car got up to 6mph in a turn, the oscillating feedback of one heavy front wheel getting the other wheel going to shaking too. The shimmy there, like all shimmies, began as something very small. The cure was a bit of damping, in the form of a VW steering damper.
In the case of my bike, a bit of preload headset bearing friction has done the same cure in the simplest way possible.
Again, a shimmy starts out as something very, very small. It requires very little damping to kill it on the spot, the microscopic-level spot, you might say! I don't think this basic point has been made before in the literature you get when Googling bicycle shimmy.
Good articles here explain viewpoints on cause and cure.
Well, it happened to be that in the past week my CCS had become shimmy-prone.
I could not ride with hands off the bar at 12mph or more without a progressive, nasty shimmy propagating.
Made no difference if I locked out the fork or not.
Nothing had been recently changed. But a shimmy was now my companion on every ride.
The headstock bearing was free and without any perceptable play.
Bear in mind, my short handle bar, my non-stock Michelin Protek Urban tires, and other factors make my bike different than stock...sort of changing its tuning, so to speak, regarding the shimmy that almost any bike can develop given circumstances.
Yet, I rode many, many miles before without any shimmy.
Shimmy is a self-amplifying positive feedback mechanism. It starts small, so small you cannot notice it. It must be damped, I find, before it can grow larger. The expert articles linked above don't make this simple point: damping the shimmy before it can grow out of control may be important to curing your shimmy, if you ever have such trouble.
My own bike's cure was effected by tightening the headset bearing just a bit, putting a bit of preload on it (normally a bad idea). The resultant friction is not enough to make hands-free riding at all difficult. But it has banished the formerly nasty shimmy entirely.
Many years ago I restored and drove a 1922 Model T Ford as my sole car. It had a perfectly fitted front end, no shake or looseness in any of the various joints. It would shimmy the car to a halt once the car got up to 6mph in a turn, the oscillating feedback of one heavy front wheel getting the other wheel going to shaking too. The shimmy there, like all shimmies, began as something very small. The cure was a bit of damping, in the form of a VW steering damper.
In the case of my bike, a bit of preload headset bearing friction has done the same cure in the simplest way possible.
Again, a shimmy starts out as something very, very small. It requires very little damping to kill it on the spot, the microscopic-level spot, you might say! I don't think this basic point has been made before in the literature you get when Googling bicycle shimmy.
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